Residential Concrete

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d e t a i l i n g a n d s p e c i f i c a t i o n g u i d er e s i d e n t i a l c o n c r e t e

preface

This technical manual is published by theCement & Concrete Association of NewZealand with funding assistance from theNew Zealand Concrete MasonryAssociation.

The construction details containedwithin this manual have been developedbased on extensive research both locallyand internationally. They are designed togive examples representative of goodpractice, rather than a complete range ofpossible alternatives.

The manual is written by Morten Gjerde,Lecturer and CCANZ Fellow at VictoriaUniversity of Wellington, School ofArchitecture.

Heartfelt thanks to the following people,without whose assistance this would nothave been possible:

3

Waterproof with usResene X-200 Acrylic Waterproofing

Membrane occupies pride of place in the

Resene range of waterproofing products.

With Resene X-200, most surfaces can

be waterproofed and weatherproofed

with a two-coat system*. Application

costs are therefore similar to any two

coats of conventional paint, combined

with the benefits of multi coat high build

systems.

Resene X-200 uniquely combines low

viscosity with high build ensuring

excellent penetration into

cracks and pores,

resulting in superb

adhesion.

Resene X-200 high build

properties allow the

development of a tough,

durable and continuous

membrane, while non-

asbestos fibre reinforcement increases

tensile strength.

Resene also manufactures and sells a

full range of textured coatings and

specialist finishes to give you and your

client the finish you desire. From high

builds to aggregate textured coatings,

we have the range to suit every taste.

To find out more and obtain copies of

the X-200 Data Sheet (D62) or textured

coatings and specialist finishes

specifications (21e/i), call 0800 RESENE

(737 363), see your

n e a r e s t R e s e n e

ColorShop, or visit the

Resene website at

www.resene.co.nz

* An additional coat of X-200 may be required on concreteblock due to regional variations in standards.

Research assistance:Rachel ChanPeter LoughOliver MarkhamNancy BakkerGrant Taylor

Peer review:Daniel BagustPhilip BlairRoss CatoJohn GibbonsDerek LawleyNigel MarshallAndy Wilton

Typing:Tricia Hawkins

Editing:Grant ThomasDene Cook

5contents

General Information . . . . . . . . . . . . .7

Concrete Masonry . . . . . . . . . . . . . . .13

Insulating Concrete Formwork . . . . . .35

Precast Concrete . . . . . . . . . . . . . . . .55

Concrete Cast In-Situ . . . . . . . . . . . .77

References . . . . . . . . . . . . . . . . . . . .95

ISBN 0-908956-12-6

TM36

Cement & Concrete Association of New Zealand

Level 6, 142 Featherston St, Wellington.

P O Box 448, Wellington.

Tel: (04) 499 8820, Fax: (04) 499 7760. Email: [email protected]

Cement & Concrete Association of New Zealand 2000

Except where the Copyright Act allows, no part of this publication may be reproduced,

stored in any retrieval system in any form, or transmitted by any means, without the prior

permission in writing of the Cement & Concrete Association of New Zealand.

The information provided in this manual has been prepared with all due care; however the

Cement & Concrete Association of New Zealand accepts no liability arising from its use.

residential concrete detail ing and specif ication guide

6

Mann House in Auckland by Ian Juriss.

General Information

7

General Information

Concrete is well known to manyNew Zealanders as a building material.Being a country of doers has meant thatnot only are we familiar with concrete butalso many have had personal experiencewith it. Footpaths, garden walls, garagesand sculptures stand as testament to thishands-on experience.

In the construction industry, concrete isthe most widely used material both hereand overseas. Commercial structuresfrom single to multi-storey continue to bebuilt in concrete. Most residentialconstruction is based on the concreteground floor slab and our infrastructure,from underground pipes to bridges, islargely constructed of the material.

The building industry in New Zealand iswell resourced to construct in concrete.Raw materials are readily availablethroughout the country. The techniquesfor constructing formwork, placingconcrete, erecting precast elements andbuilding in masonry are to a very highstandard internationally. The design ofconcrete structures by local engineers leadthe world in many areas. The existence ofseveral quality suppliers of precaststructural systems and other proprietaryelements in the marketplace allowdesigners and builders competitivepricing, extensive system choice andexcellent technical support.

For all that, New Zealanders continue tofavour timber framing for theconstruction of their houses. It is notunusual to see a design modelled on themassive homes of the Mediterranean,built using spaced timber studs with athin cladding of stucco or acrylic plasteron rigid board. Many designers andhomeowners in this country prefer tocontinue to use systems and techniqueswith which they are familiar.

Concrete construction has been widelyused for housing throughout Europe andto a lesser extent in the United States. Itwould be difficult to think of the work by

Le Corbusier, Adolf Loos and morerecently Herzog and deMuron withoutconjuring up images of concrete. Marketresearch has been carried out in an effortto identify why concrete is not used morereadily in the residential constructionsector in New Zealand. These resultsindicates that there is inadequateinformation for those wanting to designand build concrete houses. There is also alack of builders who are comfortablebuilding concrete walls and suspendedfloors in the domestic context. Theprocesses involved in building in concreteare different to those employed in timberframing and cladding. Builderscomfortable with concrete have tended tobecome established in commercialconstruction. While the research pointedto an enthusiasm for concrete homes,designers and builders tend to stay withfamiliar materials and processes.

This publication seeks to bridge theknowledge gap for designers and buildersof concrete homes. It does not howeverclaim to fulfil all their information needs.It has been structured to give an overviewof the principles and highlight the criticalissues facing designers and builders. Theconstruction industry has been widelyconsulted and research has been carriedout both locally and internationally. Thedetails have been prepared to present abroad range of construction scenarios.The designer or the builder using thismanual may find the need to changerelationships or sizes shown to suit theirown purposes. The intention has been topresent a starting point from whichspecific details can be developed. Thedetails shown here have been checked forsuitability for New Zealand conditions.Provided the detailing principles areadhered to, others should perform equallywell.

introduction

The raw materials for concreteare readily available.


8

scope

This document has been prepared as a general guide to thedesign and construction of the single family house and projectsof similar scale in New Zealand.

Although this manual does not specifically address fire resistanceand sound transmission ratings, the adjacent table demonstratesthe values that can be achieved with appropriate detailing.

It presents materials and systems that are commonly available inNew Zealand. Some, such as timber joinery and concrete itself,have been in use for several generations. Others have recentlycome into the local market and industry experience with some ofthese may be limited. On the other hand, building products notavailable in New Zealand have not been incorporated. To do sowould inaccurately present the range of materials available here.

The construction, specification and detailing issues are presentedin the New Zealand context. We have specific and often uniqueways of doing things. The New Zealand environmentalconditions are also unique.

This book is principally concerned with design and constructionissues. While it does touch upon topics such as thermalperformance and structural engineering, it is not meant to serveas a guide in these areas. Structural design is still best left to theprofessionals except in those areas where non-specific designstandards are available. Concrete masonry is one such formatwith NZS 4229 having been revised in 1999.

The Cement & Concrete Association of New Zealand produces arange of other publications that may be of interest to thedesigners and builders of concrete homes. Further information isavailable at www.cca.org.nz.

Typical fire and sound transmission ratings that can be achievedwith concrete systems when appropriately detailed.

SILL DETAIL

Paving level

Butyl rubber sillflashing

Reinforced conc.slab

Recessed timber door& sill

Floor coverings

Non structural conc.veneer

Insulation

Structural conc. panelPanel Thickness Fire Rating Sound Transmission

Class (STC) rating

100 mm 90 minutes 44



200 mm >240 minutes 58

9Objectives

Successful architectural detailing requiresattention to many factors. As with mostaspects of building, it is often necessaryto think laterally to achieve results thatare both poetic and satisfy pragmaticgoals.

First off, it is important to be able toclearly identify the detailing objectives.These may come under headings such as:

cost

appearance and aesthetics

buildability

materials usage

routine maintenance

All successful design and detailing effortswill consider these factors. The designermay make value judgments through theprocess, placing the importance of oneaspect above another. The critical thing isto be aware of these considerations andto understand the consequences offavouring any one over the other.

Environment

It is also important to consider thespecific environment that the details areto exist in. It is critical to acknowledgeand design for:

prevailing winds and wind patternscreated by the landscape or otherbuildings

rain and other weather that can beexpected

UV exposure

dust and pollutants that may be inthe air and settle on the building

corrosive elements in the air such assalt spray

moisture, either rising from theground, or as general humidity

Specific environments can vary from siteto site and even on different faces of thesame building. While exposed concretemasonry may be appropriate on thesunny north face of a house, its use onthe south side of a damp site could

quickly see mould and other organicgrowth develop, even with regularcleaning. If inappropriate materials areused or poor detailing choices are made,the building appearance can deterioratequickly.

Material properties

Concrete has a number of special andunique qualities that make it an idealconstruction medium, particularly indomestic applications. These include:

high durability

thermal mass benefits when usedappropriately

ability to form and shape

enclosure of space and structure inone material

ability to form integral surfacefinishes and colour

relatively inert and compatible withmost other buildings materials

excellent acoustic and fire resistantproperties

Along with these qualities are someinherent limitations that the designershould bear in mind:

detailing considerations

Frank Lloyd Wright was aninnovator with concrete.

Grigg House by Miles Warren.


10

once cast it is difficult to change

not sufficiently waterproof on its own

sharp corners or edges can bevulnerable to mechanical damage

Once the decision to use a concretestructure in residential projects is made,the designer and the builder must findways of optimising the positive attributeswhile minimising the negative aspects ofconcrete. The best way of ensuring this isthrough adequate and consideredplanning. This Guide is one resource tohelp with this planning.

Maintenance

Planning for routine maintenance of thebuilding, and in particular of the details,must be borne in mind. All materials anddetails perform better when they aremaintained. Such maintenance mayinclude washing, replacement of seals andsealants and re-application ofwaterproofing coatings.

Decisions made by the builder ordesigner may place high demands on thehomeowner to maintain certain details.Often the homeowner is not consulted orconsidered at the time, a point that isparticularly true of homes builtspeculatively.

Homeowners, where appropriate, shouldbe consulted with over maintenanceissues. In all cases, they should be madeaware of routine maintenancerequirements. The lifetime success of theproject will benefit.

An example of exposedaggregate finish.

Sargent House in Auckland by Ron Sang

General Information

11

moisture control

Concrete, although used in the construction of water tanks, isnot generally considered to be sufficiently waterproof forhousing without supplementary waterproofing systems. Not onlyis concrete water permeable, it also contains excess water fromthe construction process that must be allowed to escape. Thismoisture can, if not dealt with, continue to plague thehomeowner. As a rule of thumb concrete requires one monthper 25 mm of thickness to dry (from each exposed face)assuming dry conditions. This means that under ideal conditionsa 100 mm thick concrete wall will require two months dryingtime if both faces are left exposed for that period.

Finishes that are applied to exterior surfaces of concrete whichhave not dried adequately, may be affected by the tendency ofwater to escape to the warm side. This could lead to bubbling ofthe surface finish.

The external moisture clauses of the New Zealand Building Codeare increasingly being complied with through the use of paintedmembrane systems. These systems are continuing to develop andthere are a number that have proven records in New Zealandconditions. Their use has increased the options for designers butat the same time designers must ensure that sound detailing andbuilding principles are not ignored.

If a strategy of reliance on painted membrane systems has beenadopted, it is advisable to thoroughly investigate the systemsunder consideration. Speak to those who have applied theproducts and have experience of their performance. Also obtaintest results and manufacturers guarantees of performance.

Internal moisture control is often not considered by designersbut is critical to the comfort and enjoyment of the home. Thebest method of assuring that the concrete home performs well inthis regard is to insulate well and to specify appropriate finishesin those rooms where high moisture levels can be anticipated.

The enjoyment of a well designed concrete home will beenhanced by the designer considering the environment, materialproperties and sound detailing principles.

thermal performance and insultationThermal mass within the building envelope can providesignificant benefits in terms of both energy efficiency andcomfort.

Maximising the thermal mass benefits of concrete requiresconsideration of a number of issues including: site and buildinglocation and orientation, insulation placement, glazingplacement and orientation, and usage patterns, to mention a few.

This manual does not attempt to cover issues which need to beconsidered in maximising the benefits of thermal mass.

Designers wishing to check thermal properties of concretehomes for code compliance should refer to two New Zealandstandards: NZS 4214 provides the means of calculating thethermal resistance of building elements, and NZS 4218 definesminimum requirements for the various elements of a house (iewalls, roof, floor).

This house will be left unpainted until allconstruction moisture has escaped.

A contemporary concrete house.

Concrete Masonry

13

Concrete Masonry

General . . . . . . . . . . . . . . . . . . .15

Design Issues . . . . . . . . . . . . . .16

Specification . . . . . . . . . . . . . .19

Construction . . . . . . . . . . . . . . .21

Details . . . . . . . . . . . . . . . . . . .22

Concrete Masonry

15

Concrete masonry or blockwork has a long association with residentialconstruction in New Zealand. Aswell as offering all the positive attributesof the other forms of concrete it is aneasy format to use.

The use of concrete masonry has beenwell supported by the blockmanufacturers throughout the country.Special profiles are available to suit all thedetailing conditions that can beanticipated. The range of productscontinues to be expanded as blocks withspecial surface finishes, sizes and thermalcharacteristics are put to the market.

In effect concrete masonry is a type ofpermanent formwork for concrete. Thegrout fill working in conjunction with thereinforcing steel provides the structuralstrength. New research carried out byNew Zealand universities has lead to areduction in the amount of horizontalreinforcing steel and grout fill required.140 mm wide (15 Series) concretemasonry has also been shown to bestructurally appropriate for mostresidential projects. These changes havebeen incorporated into the recentlyreleased update of NZS 4229:1999, theStandard for non-specific concretemasonry design.

Advantages of concrete masonry

economy particularly when theconstruction module is fully exploited

does not require special or costlyequipment to install

modular units are relatively easy tohandle and can be delivered to mostbuildings sites

stop and start of construction is easyto incorporate structurally andarchitecturally

range of profiles allowing for mostdetailing requirements

interesting architectural scale andsurface textures

The qualities and advantages of concretemasonry certainly make it an appealingmaterial to consider for residentialconstruction.

Until the nineteen -seventies NewZealand houses built of blockwork usedcavity wall construction techniques.Concrete masonry is more porous thanmost other forms of concrete. The blocksthemselves are permeable, particularlywhen they are manufactured using thelightweight pumice aggregate typical ofthe upper half of the North Island. It ishowever the mortar joints which are thereal culprit. As the mortar dries andshrinks, cracks develop against adjoiningblocks. Traditional cavity wallconstruction assumes moisture will beable to penetrate the outer skin, but thendrop to the bottom of the cavity and outthrough weep holes without affecting theinner skin. The outer skin of the wall alsoserves to conceal the waterproofingmembrane on the outer surface of theinner skin.

Time pressures and increases in the costof construction have meant that thiseffective traditional method ofconstruction has generally been replacedby the single skin masonry wall. As hasbeen discussed earlier in this guide thechange has been justified through thedevelopment of new materials whicheffectively seal the external surfaces whilealso serving as paint or plaster finishes.This is often in conjunction with rigidinsulation. NZS 4229: 1999 has adoptedthe use of acrylic membranes asappropriate waterproofing solutions.

Broderick House by Warren & Mahoney


16

design issues

Modular setout

While other forms of concrete construction allow freedom ofshape and size, the modular nature of blockwork directs manydesign considerations. For reasons of economy and ease ofconstruction, the modular height of units typically 100 mm or200 mm should be adhered to. This applies to overall heightsof walls as well as openings within walls. Sticking to a runningmodule of 200 mm will provide economy, however, the length ofunits can be easily cut. If the module is seen, the designer maywish to specify the position of the cut units.

Joints

The mortar joint between blocks has a number of functions. Itsprimary function is to bond adjoining blocks together. This is apermanent requirement for those blocks that are not to havefilled cores. The grout fill will otherwise take over as the bondingmechanism. Another function of the joint is to take upconstruction or manufacturing tolerances as slight variations inblock sizes may occur. Finally the joint contributes significantlyto the appearance of the concrete masonry wall. The industrynorm of a 10 mm joint is generally considered to be a goodproportion when compared to the individual masonry unit. Thiswidth can be varied by the designer to suit particularrequirements. When blockwork is designed to be left exposed,the colour of the joint is a consideration. It is, however, theprofile which offers the designer the greatest number ofvariations to suit aesthetic or weathering requirements.

Profiles of typical joints that can be specified are shown in theillustration to the left. Combining joint profiles, such asalternating flush with struck to suggest a different module, orraked horizontals and flush vertical joints can be effective.

Bonding patterns

The way in which the concrete blocks are laid presents anotheropportunity to affect the overall appearance of a wall. Thetraditional bonding pattern for concrete masonry is the ashlar orrunning bond. Another option is the stacked bond. Beyond these

raked flush

struck weathered

concavevee

Common mortar joint profiles

Stacked bondRunning bond

Concrete Masonry

17

it is over to the designers imagination to consider the surfacepatterns and textures that can be achieved. Mario Botta, a Swissarchitect, is renowned for combining blocks of various colour,texture, height and laying position to create wonderful patternsthat become an integral part of his architecture.

Note that the bracing values for partial filled concrete masonryin NZS 4229 are based on the running bond. Partially filling astacked bond wall at 800 mm centres will leave every secondblock unbound which then becomes vulnerable underearthquake loading. It is therefore recommended to fill cells at400 mm centres or closer when using stack bonded concretemasonry.

Non-structural applications

Concrete masonry is generally used in a structural capacity, forwhich it is ideally suited. It can also be used as an external veneercladding in conjunction with other structural systems. The mostcommon is timber framing but combining structural and veneermasonry with a cavity between will allow the designer to takefull advantage of the external appearance, durability and thermalmass benefits.

Method of insulation

Appearance requirements and thermal mass objectives must beconsidered at the same time as the insulation strategies.

The most common method of insulating a concrete masonrywall is to strap and line the internal face, fitting insulationbetween the strapping. An alternative approach is to fixinsulation externally either in the form of rigid polystyrene sheetfixed in place with an external coating or by strapping andcladding with insulation between.

Proprietary self-insulating concrete block systems are available inNew Zealand. Such systems allow both faces of the concretemasonry. This is achieved through the use of a biscuit ofpolystyrene fixed in a cavity near the exterior surface of the block.

Concrete masonry built using the cavity method allows foreffective use of insulation, thermal mass and the blockworkaesthetic. Insulation was often not included in the traditionalcavity blockwork which gave these houses the reputation ofbeing cold. While cavity construction allows insulation to beinstalled in the cavity, the detailing should ensure that the cavitywill allow free drainage and that the type of insulation specifiedis capable of withstanding moisture.

insulation incavity

veneer tie

water proofingmembrane

weephole

concretemasonryveneer

15 seriesstructuralconcretemasonry

10 series concrete masonry veneer over 15 seriesstructural wall. Cavity should be insulated.


18

Waterproofing

The considerations for choice of waterproofing system are setout in the General Section. It is most important to considerappropriate and effective waterproofing strategies for concretemasonry due to its porosity. Cracks that develop between themortar and blocks are also areas of vulnerability that thewaterproofing system must be capable of bridging.

Unpainted and unsealed blockwork is an option in somecircumstances such as when using veneer construction or ingarages and uninhabited basements. It is important neverthelessto bear in mind the affect water can have on the masonry. Watercan bring salts to the surface in the form of efflorescence, leavingan unsightly and unpredictable white pattern on the surface.

Plan view of bond beam at control joint

Shrinkage control joint

verticalreinforcing

bondbeam

full heightshrinkagecontrol joint

horizontalreinforcing steel

verticalreinforcing steel

sealantboth faces

debondedbar

shrinkage central joint

Concrete Masonry

19

Shrinkage control joints

Shrinkage control joints are necessary toensure that shrinkage cracking occurs in acontrolled manner and allows movementdue to thermal changes. NZS 4229specifies requirements for control joints.These should occur at approximately sixmetre centres and will affect theappearance of the project when themasonry is to be left exposed or painted.Applied finishes such as stucco plastershould also acknowledge the control jointto avoid consequential cracking. Thedesigner should take charge of the controljoint setout and carry out detailing asillustrated on the previous page to avoidany surprises on site.

specification

There are several New Zealand Standardsthat may be relevant to the writtenspecification. These include the following:

NZS 4229:1999Concrete masonry buildings notrequiring specific engineering design

NZS 4230:1990 Code of practice for the design ofmasonry structures

NZS 4210:1989Code of practice for masonryconstruction: materials and workmanship

AS/NZS 4548Guide to long-life coatings for concreteand masonry

NZS 4251:1974Code of practice for solid plastering

NZS 3604:1999Non specific design Light timber framebuildings

Materials

All materials should be procured from adependable source.

Where appropriate, ensure that qualityrecords are obtained and kept for easyretrieval, should they be required.

Concrete blocksshould be dry and remain so until theyare used.Manufacture must comply withAS/NZS 4455Excess moisture in any of the materialscan reduce structural quality and requirethe blocks to have to dry longer beforesurface finishes can be applied.

Steel reinforcingshould be maintained free of dirt andorganic material.

Mortarmixing ratio (cement/sand/lime/water) tocomply with NZS 4210To provide a compressive strength of notless than 12.5 MPa.

Concrete blocks stackedon pallets.


20

Groutmixing ratio to comply with NZS 4210. To provide acompressive strength of not less that 17.5 MPa.Spread value 450 530 mm

Sandchloride levels should not exceed 0.04% by dry weight of sand

Waterone of the most important yet overlooked components of highquality concrete. Water must be clean and free from excess alkali,salt, silt and organic matter.

Workmanship

Concrete masonry work should ideally be carried out byqualified tradesmen. As a minimum, tradesmen should haveexperience in the required areas of construction. In someinstances, such as detailed structural work, it is desirable toemploy a Registered Mason.

All concrete masonry work should be carried out underadequate supervision.

Grout all cells that

1. contain reinforcing

2. are required to be filled as part of the design requirements

Grouting should follow the procedures set out in NZS 4210.

Form construction joints in accordance with NZS 4210 betweengrout pours and between the blockwork and any hardenedconcrete.

The block layer must coordinate his work with the work of othertrades. Coordination should take place well in advance of thework being done.

The block layer must build in all elements including fixings,bolts, ties and any service requirements as called for, and/ornecessary for the completion of the job.

Once concrete masonry work is complete all block work must becleaned.

20 series

15 series

10 series

A selection of concrete masonry profiles that are available. Consultwith manufacturers to determine the full range.

Concrete Masonry

21

construction

Planning the job

One of the most important activities when building in concretemasonry is planning the project. The economy of concretemasonry block work can only be maximised with properplanning.

Consider the module. Try to minimise the number of cut unitsand to maximise the sizes of any units to be cut. Doing so willalso serve to keep costs to a minimum. Check with the designerwho may have specified the placement of any cut units.

Plan the sequence of activities carefully. This is especiallyimportant with respect to services that will occur in masonrywalls.

Setting out

Reinforcing steel must be set out at foundation levels to fallwithin the planned location of cells.

Normally the concrete masonry requires a vertical steel setout of800 mm centre to centre spacing. Note that foundation stirrupstypically occur at 600 mm centres meaning that only one inevery four stirrups can be extended as vertical steel.

Setting out of foundations to suit the specific requirements ofthe design is also critical. These include

allowing for any specified overhangs of concrete block orveneer

allowing for set downs or insets at door openings.

Builders should take extra care when setting out services thatwill be concealed in masonry walls. This requires fullcoordination between trades such as plumbers or electriciansand the reinforcing steel trade.

Weather conditions

Wet weather can cause build up of water in the blocks, as theyare relatively porous. Excess water can reduce the strength ofgrout. This is particularly of concern where water is retained atthe bottom of, or between lifts of, grouted cells.

Rain onto fresh mortar can erode its surface, affecting theappearance and possibly the structural strength of the mortarjoints.

Cold conditions will not allow the mortar or grout to setproperly. Concrete masonry and grout should not be placed intemperatures less than 4C.

Hot weather conditions are generally not a problem for concretemasonry in New Zealand. However, prolonged dry conditionsmay warrant attention when laying or grouting the masonry.Overly dry blocks will draw moisture out of the grout or mortartoo quickly thereby affecting the bond with the blocks. It istherefore recommended that the blocks be wet lightly on thosesurfaces which will be against the mortar or grout.

Provided the blocks are not too dry the curing of the mortar andgrout does not require special care. If strong hot winds or directsunlight in the middle of the summer are anticipated it would beprudent to ensure the mortar and block surfaces are kept moistfor the first three to four days after being placed.

Protection

Builders should take care to protect finished concrete masonryfrom damage which could arise through the building process.This is particularly important with blockwork and veneer thathas been designed to be left exposed.

While in most cases it will be impractical to erect full protectionfor the masonry it should be possible to anticipate work that willcreate risks to the completed walls. Plywood sheets serve as anexcellent form of protection.

It is necessary to coordinate reinforcingplacement with block setout.

Kew House by Melling Morse Architects

WALL TO FLOOR

INTERMEDIATE FLOOR

WALL TO ROOF

Insulation

Internal lining

Building paper continuous

100 x 50 on DPC

Reinforced concrete slab

Reinforced concrete footing

DPC over 25mm sandblinding

Compacted granularhardfill

15 series conc. masonryfoundation wall.Starter bars atrequired spacing.

Waterproofing systemextend min 50 belowfloor level

15 series conc. masonryvertical & horizontalreinforcing per NZS 4229

Unpaved G.L.

Paved G.L.

Internal linings on timberstrapping

Continuous boundary joist onDPC

Bolt connection to bondbeam per NZS 4229

Particle board flooring

Joist hanger

MDF skirtingExternal waterproofingsystem

acrylic plaster & paint

acrylic paint system

sand/cement plastersystem & paint

sealer

External waterproofingsystem

Continuous timber plateon DPC Bond beam in accordance

with NZS 4229

15 series conc. masonry

Ceiling lining on battens

Roofing onbuilding paperon wire netting

Timber trusses

Fascia

Insulation

Cast in bolt fixings

Bond beam at floorlevel

Timber strapping

100

MIN

150

MIN


22

Internally insulated wall section

This wall section presents:

single wythe 15 series concretemasonry

building paper on the inside face ofthe masonry acting as a second line ofdefence against moisture penetration

strapping and lining on the interior

insulation between strapping

concrete masonry foundation wallacting as permanent formwork forconcrete slab on grade.

These details separate the thermal massof the concrete masonry from the interiorspace. It also allows the concretemasonry to be expressed as anarchitectural finish externally.

WALL TO FLOOR

INTERMEDIATE FLOOR

WALL TO ROOF

Paved G.L.

Unpaved G.L.

Acrylic plaster system

Proprietary externalinsulation system

Reinforced concreteperimeter edge beam

Sand blinding oncompacted hardfill

DPC

Fix skirting & other elementsby plug & screw on DPC

Internal finishes paint system plaster system none

Reinforced conc. slab

Bond beam

Suspended ceiling systemfor services & lighting

Proprietary concrete floorsystem

Acrylic plaster system

Proprietary externalinsulation system

Bond beam

Suspended ceiling systemfor services & lighting

Concete floor system

Acrylic plasterwaterproofing system

External insulation systemButyl on plywood oninsulation on DPC

Butyl as upstand dressed &sealed into chase in mortarjoint

FALL Extend insulation andwaterproofing over butyl withsealant bead

150

MIN 10

0MI

N 50 MIN

Concrete Masonry Detai ls

23

Externally insulated wall section

This wall section presents

single wythe 15 series concretemasonry

exterior insulation and waterproofingsystem

concrete roof system

concrete intermediate floor system

reinforced concrete slab withthickened edge perimeter foundation.

This construction allows full advantage to be taken of the thermal mass in thehouse. The texture/finish of concretemasonry can be expressed internally.

WALL TO FLOOR

WALL TO ROOF

Paved G.L.

Unpaved G.L.

Masonry ties in accordancewith NZS 4229

Sand blinding oncompacted hardfill

DPC

Skirting


10 series conc. block veneer

75mm high weep holes@ 800 centres

100mm insulationInternal lining

Building paper continuousVentilated cavity


Roofing onbuilding paperon wire netting

Timber trusses

Fascia

Continuous 10mm gapfor ventilation

10 series conc. block veneer

Ventilated cavity

Masonry ties. Materialto suit environment

Waterproofing on slopedplaster

Bottom plate bolted tofoundation

150

MIN 10

0MI

N 50 MIN

75 max40 min

10


24

Concrete masonry veneer

Concrete masonry veneer has beenwidely used in New Zealand houseconstruction.

The principle of a ventilated cavity cangive a greater source of security to thehomeowner and designer alike.

As with all masonry, it is important toconsider the modular height in settingout openings and heights of walls. Thisexample shows the veneer stopping shortof the soffit lining as a way of expressingthe nature of the masonry on a veneer.This also stops the lining from meetingthe masonry off the height module.

Note the requirements in NZS 4229 andNZS 3604 for the base material andprotection for masonry ties in certainexposures.

RAISED GROUND FLOOR

WALL TO FLOOR

Paved G.L.

Unpaved G.L.

External cladding fixed overbuilding paper

Insulation

Perimeter edge beam Sand blinding oncompacted hardfill

DPC

Fix skirting & other elementsby plug & screw on DPC


Openings in wall forventilation to comply withNZS 3604

Sisalation or under floorinsulation

Particle board flooring

Timber skirting

Internal finish

20 series reinforced conc.masonry footing on concretebed

External waterproofingand insulation system

Bond beam

M16 bolt to complywith NZS 4229

Timber stringer onDPC


Timber strapping fixed tosolid filled cells over DPC


Cement/sand plaster oracrylic plaster internal finish

150

MIN 10

0MI

N 50 MIN


25

Externally insulated wall

This system is designed to allow atraditional external appearance. Almost any external cladding can bechosen. Timber weatherboards areillustrated here.

The internal finish should be applieddirectly to concrete masonry to allow thefull advantage of thermal mass.

Foundation crawl space

This construction detail is ideally suitedto a sloping site.

The use of concrete masonry as afoundation footing can be botheconomical and time saving, particularlyon sloping sites or those with limitedaccess.

SILL DETAIL

HEAD DETAIL

15 series conc.masonry

Externalwaterproofingsystem

Extend waterproofingover plaster screedto falls and under sillgenerally

Galvanised metalflashing

Interior lining

Insulation

Timber strappingBuilding paper

TImber reveal

Externalwaterproofingsystem

15 series lintelblock

Timber frame onpacking. Plugand screw tomasonry

Sealant overbacking rod

Timber reveal

Architrave

Building paper

Timber strapping

Insulation

Interior lining

Glazing in timberwindow frame

Architrave


26

Timber window details

Timber joinery is still the preference formany homeowners. Modern timberwindows are well made and draft free. Itis important to build these windows unitsin to ensure weathertightness.

The details illustrated here indicate anappropriate method for doing so.

SILL DETAIL

JAMB DETAIL

HEAD DETAIL

Position frame toallow drainage fromwithin

Run waterproofing upunder reveal

Continuous sealantbead

Waterproofing system

Build up waterproofingmembrane and formdrip

Continuous sealantbead

A

A

DPC overwaterproofingmembrane andover buildingpaper

Timber reveal

Timber strapping

Interior lining

Building paper

Insulation

20 seriesrebated block.Reinforce perNZS 4229

20 series rebatedlintel block

Remove projecting sill

Insulation

Building paper

Interior lining

Timber strapping

20 seriesrebated sillblock.

InsulationBuilding paperInterior lining

Timber strapping

Timber reveal

DPC over water-proofing membraneand over buildingpaper

Waterproofing system


27

Aluminium window details

Aluminium is the most common materialfor exterior door and window frames inresidential construction.

These details demonstrate the use ofaluminium window frames in 20 seriesblockwork using rebated blocks. Therebated block allows a positive step forthe frame to fit against.

When using an exterior membranesystem be sure to extend it under thewindow frames prior to their installation.DPC should lap onto membrane and overbuilding paper.

Note the requirement by some windowmanufacturers to fit an angle (note A) inhigh wind areas to relieve the pressureson the sealant joint.

It is quite common to remove theprojecting profile from the sill block toachieve a more flush appearance. Notethat this may cause staining underwindows as dirt that has settled on thesill gets washed down by rain.

SILL DETAIL

JAMB DETAIL

HEAD DETAIL

Acrylic interiorplaster system.Neatly finish to timberframe

DPC

Form recess atopenings

Fairface concretefoundation beyond

EIFS beyond

External InsulatingFinishing System(EIFS)

15 series lintelblockDPC

Sealant

Continuous headflashing

Glazed timberdoor

Conc. slab

Rebate slab fortimber sill

Acrylic interiorplaster system.Neatly finished to timberframe

External InsulatingFinishing System(EIFS)

15 series lintelblock on end

DPC

Sealant

Glazed timberdoor

Timber packing

Timber doorhead and bead

Timber bead

Timber packing

Glazed timberdoor

Timber doorsill

Timberangle fillet

Timber doorjamb


28

Timber door details

The external ridgid insulation systemallows the concrete masonry to be leftexposed, or receive a thin finish asillustrated here. There may be thermalbenefits to the home owner in adoptingthis strategy.

The timber frame is supported on timberpacking which is continuous andplastered over. The plaster system shouldbe reinforced across this piece.

Sealant is applied between the timberframe and the insulation system as aweather seal.

SILL DETAIL

JAMB DETAIL

HEAD DETAIL

Shaped timberthreshold

Sand/cementplaster system

Concrete slab

Paving level

Fairface conc.foundation beyond

Bring DPC overleading edge ofslab

Aluminium door sillframe

Aluminium doorframe with weatherstrip on botttomedge

EIFS

External InsulatingFinishing System(EIFS)15 series lintelblock

Sealant bead.Leave 50mm highgap at bottoms ofjambs for water toescape

DPC

Glazed hinged door inaluminium frame

External InsulatingFinishing System(EIFS)15 series block

Sealant bead.Leave 50mm highgap at bottoms ofjambs for water toescape

DPC

Glazed hinged door inaluminium frame

Expresscontroljoint

Expresscontroljoint

Sand/cementplaster system

Form recess at openings


29

Aluminium door details

These details show the aluminium doorframe set in 15 series blockwork not usingthe rebated profile. This presents greaterflexibility for the designer to positionframe in depth of block. It may be pref-erable to use rebated block profiles inopenings as this gives maximumweathering protection.

Details show that the thermal mass isfully available to the interior space as theinsulation is placed externally.

The detail shows that the upstand legfrom the sill frame across the thresholdhas been removed. This prevents it beingdamaged by being walked over.

SILL DETAIL SILL DETAIL

HEAD DETAIL HEAD DETAIL

10 seriesmasonry veneer

Masonry ties inaccordance withNZS 4229

Sealant betweenaluminium windowframe and sill tile

Building paper

Galvanisedmetal sillflashing.Lap oversill tile

125 x 125 x 8mm Hotdipped galvanisedM.S. angle lintel fixedback to framing

Sealant

Weep holes

Lap building paperover M.S. angle lintel


TimberLintel perNZS 3604

Galvanisedmetal headflashing.


Lap buildingpaper over M.S.angle lintel

Weep holesTimberLintel perNZS 3604

10seriesmasonryveneer

Masonryties inaccordancewith NZS4229

Aluminium frame withtimber reveal

Sill tiles onplaster

Timberframingwithinsulationbetween

Interiorlining

Sill tiles onplaster

Timberwindow sill

Timberwindowframe

Architrave

Continuoussupport fortimber sill.Fix overbuildingpaper

Interiorlining

Insulation

Interiorlining

Insulation

Architrave

Timberwindowframe

Interiorlining

Insulation


30

Veneer window details

The position of window frames in aveneered wall is critical to ensureadequate closure of the gap whileensuring adequate fixing for the frame.

Most aluminium window frames forresidential use are delivered to the sitewith reveals fixed in the factory. Fixingthrough the reveal, as shown, will allowthe frame to bridge the cavity.

Timber window frames, on the otherhand, may require framing support in thecavity, as shown.

Units fabricated in the factory, beforetimber and aluminium may be able tospan across the sill without fixings.


31

ROOF VERGE

Bond beam

Soffit

Casement bead

Sand/cementplaster system(19mm texturedsurface)

Metal flashing


Metal roofing on buildingpaper

Timber purlins/rafters(cantilevered verge)

Solid blocking

Internal linings over50mm timber strapping

Insulation

Building paper

PARAPET / METAL ROOF

Bond beam

Internal linings onceiling joists/rafters

Furring to fallsAcrylic plastersystem

Proprietaryexternal insulationsystem

Metal flashing dressed &sealed into chase inmortar joint

FALL

Bond beam

Metal roofing to falls

PARAPET / METAL ROOF

Bond beam

FALL

Butyl as upstand dressed& sealed into chase inmortar jointButyl on plywood on75x40 furring to falls

Proprietaryexternal insulationsystem

Acrylic plastersystem

Internal linings onceiling joists/rafters

Bond beam

15 series conc.masonry

Gutter overflow.Opening size tomatch downpipe.Position belowgutter freeboardheight.

Furringto falls

Metal roofing to falls

Insulation

Roof details

The use of sand/cement plaster allows asmooth uniform texture finish using amaterial similar in nature to concretemasonry.

Care must be taken to:

ensure adequate bond of sand/cement plaster to concrete masonry

follow control joints in masonrythrough sand/cement plaster

A suitable paint finish will provideweatherproofing.

The use of an internal gutter suits manyof the contemporary expressions ofarchitectural design. Dimensions of sucha gutter should be to suit the expectedrainwater flow, but in no case should itbe less than 600 mm for ease ofcleaning.

Provide secondary overflow capacity toensure rainwater does not back up insidehouse.


32

BLOCK WALL / VENEER JUNCTION

Internal liningson timber strappingon building paper

Timber floor joist

FlooringExternal waterproofingsystem

acrylic plaster & paint

acrylic paint system

sand/cement plastersystem & paint

sealer

Insulation

25 seriesbond beam

20 series concreteblock

10 series concreteblock veneer

Timber platebolted to bondbeam on DPC

Blocking

Ceiling on timberstrapping

Suspended floor details

A hybrid form of construction withconcrete masonry ground floor structureand a lightweight structure above. Thedurability aspects and appearance ofconcrete masonry is continued with 10series veneer over the timber framing.

Suspended deck details are critical to getright particularly if they sit above interiorspaces.

When the concrete block module is seenfrom outside, it is critical to ensure thefull module carries through floor leveland that the detailing reflects this.

Services details

As with most forms of concreteconstruction, it is critical to plan forappropriate services reticulation whendetailing in concrete masonry.

When using masonry veneer constructionit is tempting to reticulate services in thecavity but this is specifically prohibited inNZS 4229.

When using partial fill concrete masonry,dropping services from ceiling level in anempty cell can make the job much easier,particularly as a retrofit. It is advisable tocast sleeves into the bond beam to allowthese services to be reticulated easily.Casting in additional sleeves toanticipate future alterations is alsorecommended.


33

Insulating Concrete Formwork

35


General . . . . . . . . . . . . . . . . . . .37

Design Issues . . . . . . . . . . . . . .38

Specification . . . . . . . . . . . . . .39

Construction . . . . . . . . . . . . . . .41

Details . . . . . . . . . . . . . . . . . . .43


37

Insulating concrete formwork (ICF) is a proprietary formwork system forconcrete that is left in place tobecome part of the building. ICF systemshave been available in New Zealand forthe last 10 years and during that timehave been increasingly used for bothcommercial and residential construction.ICF construction has been used for some30 years in Europe, where concreteresidential construction is quite common.

Block systems are widely available in New Zealand. Plank and panel systemsare available internationally but notcurrently in New Zealand. The forms aretypically made of expanded polystyrene,a closed cell polymer. The reinforcedconcrete core provides all the structuralcapacity of the wall.

The main advantages of these systemsare:

excellent insulation properties

low levels of air infiltration

blocks are easy to lay and fill

relatively easy to run servicesconcealed in polystyrene layer. This istrue of both new construction andrefitting work.

long life expectancy

A contemporary housebuilt using insulatedconcrete formwork.


38

design issues

Although the principle of ICF construction is similar to that ofconcrete masonry, there are some important differences for thedesigner to consider.

Module

The modular height of systems available in New Zealand istypically 300 mm. As with concrete masonry, it will be moreeconomical to work to the modular height for openings and wallheights. Most systems mechanically lock together along top andbottom edges.

ICF systems are available in widths of 200, 250 and 300 mm.Unit widths correspond to different concrete thicknesses. Thewider blocks offer increased structural capacity, little if anyinsulating increase and potentially reduce the interior floorspace. The greater thickness will give greater reveal depth atopenings which is often sought after by designers.

ICF blocks are relatively long, in the order of 1000 to 1500 mmwith many bridges between the faces. This allows the blocks tobe easily cut to length without compromising the structuralqualities. With block sizes like these, it is easy to see how thesesystems can be laid so quickly.

Proprietary systems

This part of the guide has been prepared with informationobtained from the suppliers of ICF blocks in New Zealand. Asmuch as possible, it has been the intention of the writers topresent this information in a generic manner, thereby notfavouring any one supplier.

As soon as a particular system is adopted it is advisable that thedesigner confirm all details with the particular supplier.

Applied finishes

ICF systems comply with NZBC durability requirements,provided the blocks are appropriately finished or clad forprotection from the effects of UV radiation and weather. MostICF suppliers require that claddings or finishes are approved foruse with their system. Modified acrylic plaster and paint systems,timber strapping with weatherboards, concrete masonry andstone veneers are examples of external claddings that ICFsuppliers have recommended for use.

Modified acrylic plasters, plasterboard or fibre cement sheet aretypically used as internal linings. ICF suppliers will give guidanceto the methods of fixing linings using adhesives and screws.

Typical ICF block format. Confirm thedimensions with the selected supplier.


39

Detailing fixings

One of the most important detailing considerations with ICFsystems is that of fixings. This includes fixings for bothstructural and architectural elements. The formwork units, asthey are made of polystyrene, offer limited fixing capacity. Tomake allowances for timber skirtings to be secured, the fixing ofwindows into openings and joinery fittings to be positioned, it isnecessary to cast in timber fixing blocks. These are typically 150 mm long and are secured into the concrete core by pairs ofnails that protrude off the back face. This apparently lowtechnology detail is very effective, provided the necessaryplanning has allowed them to be in the right places.

Structural elements such as concrete flooring systems can beaccommodated and are installed after the concrete has been castto the soffit level. The seating depth can vary between 50 and 75mm. The method for fixing timber floor framing to ICF walls isto secure a stringer on fixings cast into the concrete core.

specification

It should be the objective of the specification writer to structurethe documents in such a way as to encourage competitivepricing. Fortunately there are several suppliers of the forms inmost parts of New Zealand.

Once a system has been selected it is advisable to confirm alldetails and other design issues with the selected manufacturer.This includes wall thicknesses, building in details, steelreinforcing requirements and construction requirements.

It is desirable to structure the ICF sub-contract on the basis ofengineering design and supply. It may also be possible to includethe erection of the system in that subcontract.

A Producer Statement: Design, or some other evidence ofstructural capacity should be required by the specification. Thiswill assist the Territorial Authority in approving its use.Manufacturers literature and guarantees should also be requiredby the specification.

Standards referred to:

NZS 3101: 1995The design of concrete structures

NZS 3104: 1991 Specification for concrete production high grade and specialgrade

NZS 3109: 1997Concrete construction

NZS 3402: 1989Steel bars for the reinforcement of concrete

Materials

There is at present no New Zealand Standard for themanufacture of ICF units. Accordingly the designer shouldreserve the right to approve the supplier.

Timber inserts facilitate fixing of doorframes, skirtings and other joinery items.


40

ICF Blocks should be made of fire retardant materials.

In situations where fire resistance ratings are required. Thesemust be specified as not all ICF blocks provide adequate fireresistance.

Concrete infillto achieve a minimum compressive strength of 20 MPa.Maximum aggregate size to be 14 mm. Concrete slump shouldcomply with the ICF manufacturers requirements. A 100 mmslump is typical. Expansive additives must not be used in anycircumstances as these can blow out the forms.

Steel reinforcingto comply with NZS 3402.

Workmanship

Erection and filling of the system should be carried out either bythe ICF supplier or by a firm approved by them.

The installation should be carried out by persons withexperience in this type of work. All necessary and appropriateequipment and construction techniques to be employed.

The blocks are fitted together and propped in place before fillingwith concrete. Temporary wire ties may be necessary to preventthe blocks floating on the concrete fill. These should be installedevery four courses.

Allow to build in all fixings and services as detailed and requiredby various trades. Typically, such fixings are supplied by therelevant trade or by the builder, to ensure they are correct.

The ICF trade must coordinate with all other trades.

Allow to locate and form construction joints in accordance withNZS 3109.

Before placing concrete, ensure all cells are clean and reinforcingis secured in place. Consolidate concrete with a max 25 mmdiameter poker vibrator or by rodding. Vibration should ensurethat all cells are filled with well compacted concrete. Extent andheight of lifts to be in accordance with ICF manufacturersrecommendations.

Significant construction tolerances for ICF are to be expectedgiven the nature of the material. It is prudent to limit tolerancesand to ensure subcontractors are aware of them so they canmake appropriate allowances. Recommended limits are asfollows:

Deviation from plan location 20 mm

Deviation from vertical within a storey 10 mm per 3 m

Relative displacement between load 5 mmbearing walls in adjacent stories intended to be in vertical alignment

Deviation from line to planAny length up to 10 metres 5 mmAny length over 10 metres 10 mm

Deviation from horizontalAny length up to 10 metres 5 mmAny length over 10 metres 10 mm

Concrete floor systems can be easilyaccommodated in ICF construction.

Diagram showing ICF components.


41

construction

Planning the job

Due to the speed with which ICF systems can be erected, it isimportant to plan well ahead.

Follow the manufacturers recommendations for the height ofeach lift.

ICF blocks are easy to cut, allowing opportunities to deviatefrom the block module.

It is important to consider, from a construction viewpoint, thatthe ICF walls have no structural capacity until the concrete coreis cast. Therefore it is important to provide adequate proppingand support for these elements until the concrete has achievedthe appropriate structural strength.

Setting out

As with other systems covered in this guide, it is important to setout reinforcing to suit the ICF block width. This must beconfirmed prior to casting of foundations.

The ICF forms can be used for internal and external walls.


42

Weather conditions

Due to its insulating qualities, in theory concrete can be placedin colder conditions than it can into other types of formwork.However, this is rarely a factor in New Zealand conditions.

The forms themselves can be placed in most weather conditions,although the unfilled forms are susceptible to displacement inhigh winds. Concrete can be placed in the forms when it israining provided measures are taken to remove water in thebottom of the forms, which if left will mix with the concretethereby reducing its strength.

Curing and drying

ICF systems enhance concrete curing by slowing waterevaporation. This effect can increase concrete strengths.Obtain, and comply with the ICF and coating manufacturersrecommendations for drying times prior to the application ofsurface finishes.

Protection

ICF is vulnerable to mechanical damage particularly beforecladdings are applied. Protection, such as plywood sheeting,should be considered in areas of high risk during construction.

At exposed corners and edges PVC protection is recommendedas part of the cladding system.

Prolonged exposure to sunlight can cause surface deteriorationof the polystyrene. If the surface becomes scaly after a period ofexposure, this scaliness must be removed prior to the applicationof surface finishes. The minor deterioration that may occur willhave no effect on the structure of the wall. Some reduction of theinsulation properties may occur, depending on the depth ofdeterioration.

It is important to prop ICF units appropriately until concrete has set.

Stone and other veneers can be used to give thehouse a traditional appearance.

WALL / SLAB

CONCRETE FLOOR

CONCRETE ROOF

100

150

Reinforcing mesh

Insulation over DPM

Fix Butyl into chase cut into wall.fix 90 PVC angle cap to Butyledge and seal in place. Plasterdown onto PVC angle

Butyl on Plywood base

Concrete slab. Prop in place untilconc. is cured

Metal frame suspended ceiling

Construction joint

ICF block system

Reinforcing

Reinforcing

Internal finish

Rough broomed surface toensure good key

Cut hole in block at each conc.beam

TImber formwork

Internal finish

Skirting fixed to intermittenttimber block cast into conc.

Reinforced conc. topping

Conc. beam & timber infill floorsystem

Reinforcing mesh

ICF block system


DPC

Sand blindingReinforced concretefooting

PVC starter strip,forming a drip edge

ICF block systemExternal finish Internal finish

Compacted granular hardfill

Unpaved G.L.

Paved G.L.

Metal frame suspended ceiling

FALL

Concrete topping to falls

Reinforce corners ofplaster systems

Construction joint

External plaster finish


Insulating Concrete Formwork Detai ls

43

Wall section

These details indicate how the ICFconstruction system can be combinedwith various concrete floor systems.

The roof details indicate a concrete floorslab system with topping formed to falls.With all parapet conditions it is importantto make allowance for overflow in caseprimary drain becomes blocked.

Insulation is shown on top of roof slab toallow thermal mass to help moderateindoor temperatures and to preventcondensation that may develop in certainconditions.

Suspended floor detail indicates precastbeam and infill system.

A suspended ceiling can be included toconceal services and the soffit of theflooring system. With appropriateplanning and good workmanship, it ispossible to leave these surfaces exposed,thereby saving the cost of the ceiling,enjoying greater floor/ceiling heights andthe thermal mass benefits of theconcrete.

ICF can be used as permanent formworkfor foundations.

WALL / SLAB

TIMBER FLOOR

ROOF OVERHANG

150 10

0

ICF block wall

Internal lining

Ceiling battensInsulation

DPC

Top plate fixed @750max ctrs withcast in bolts

Connection platebetween top plateand truss

Timber truss

Timber stringer,fixed @ 750maxctrs. with cast inbolt

Soffit lining

Gutter

Fascia board

Building paper& timber purlin

Roofing

Malthoid strip betweentimber and concrete oruse H3 treated timber

Joist hangerContinuous slot cut inblock wall for stringer

Timber joistsFlooringExternal finish

Skirting fixed tointermittent timber blockcast into conc.

Extend insulationdown to bottomof foundation

PVC channel

SkirtingReinforced concrete slab

DPC

Compacted sand blinding

Granular hardfill

ICF block system

Internal finishExternal plaster finish.Extend to ground level

ICF block system

Paved G.L.

Unpaved G.L.


44

Wall section

The details on this page indicate atraditional sloping roof with overhang.Planning is required to cast inappropriate fixings for structural andarchitectural elements, as ICF will notsupport or transfer any loads.

The suspended timber floor must besecurely anchored to the wall to transfervertical and lateral loads. This shouldalso coincide with a horizontal bondbeam. As the intermediate floor acts as adiaphragm in this case, only onehorizontal bar is required in the bondbeam. The timber frame floor/ceilingassembly allows electrical services to beeasily reticulated, but acousticperformance is somewhat compromisedin comparison with a concrete system.

The concrete slab on grade forms aperfect base for the insulated concreteformwork system. It is important tocoordinate reinforcing steel starter barsand fixings for skirtings and the like.

HEAD DETAIL

JAMB DETAIL

SILL DETAIL

Corner strip

Form dripedge

ICF blocksystem

ICF blocksystem

Timber reveals

Timber packer

Cornerstrip

Internal finish

PVC flashing

Intermittent H3timber blocks.Fix galv. nailsskew nailed totimber & cast inconcrete infill.

Aluminium window section



Internal finish

Timber reveals

Timber plate

Internal finish


ICF blocksystem

PVC flashing

Sealant bead

Externalplasterfinish.

Timber reveals

Aluminium windowsection

Sealant

Externalplasterfinish.

Aluminium flashing

Cornerreinforcing


45

Aluminium window details

The key to fitting doors and windows intoopenings in ICF partitions is to plan for,and cast in, appropriate fixings. Thesefixings must be H3 treated or higher, asthey are generally in full contact withconcrete. These fixings are intermittent,about 150 mm long at 450 mm centrespacings. The nails on back help anchorthe timber to the concrete.

These details also make use ofaluminium flashings and sealant toensure a weathertight opening. Theflashings must be compatible with theexterior finishing systems and fixed in amanner that will not cause the acrylicplaster system to break down.

HEAD DETAIL

JAMB DETAIL

SILL DETAIL

ICF blocksystem

Modifiedacrylicplasterfinish

Intermittenttimber blocks.Fix galv. nailsskew nailed totimber & castin concreteinfill.

Timber windowframe

External finish. Carryunder flashing.

Fit timber sill overflashing & timberpacking

ICF blocksystem

Timber plate

Timber sill

PVC flashing

Modifiedacrylic plaster.Return atreveal

Internal finish.Return toreveal

Cornerprotection

Sealant

Sealant

Cornerprotection

Form dripedge

Cornerstrip

Sealant &backing rod


ICF blocksystem

Internal finish

Timber windowframe

Cornerstrip

Sill flashing

Continuous H3timber, shapedto fall


46

Timber window details

These details, like those on the facingpage, rely on the fixing capacity of castin timber blocks.

The interior finishes here are shown toreturn in to the window frame as a reveal.This is effective in creating a massivelook to the walls.

External corners of ICF are vulnerable andmust be protected with PVC cornersintegrated with the plaster system.

SILL DETAIL

JAMB DETAIL

HEAD DETAIL

Shaped Timberon DPC

Step backconcrete slabedge to suitreveal

Aluminium doorframe withtimber reveals

Reinforcedconc. slab

ICF blocksystem

Intermittent H3timber blocks.Fix galv. nailsskew nailed totimber & cast inconcrete.

ICF blocksystem

Form dripedge

Back sealantbefore planter

Corner strip

Aluminium doorframe withtimber reveals

Intermittent H3timber blocks.Fix galv. nailsskew nailed totimber & castin concreteinfill.

Front sealantafter planter

Back sealantbefore planter

Corner strip

Externalplaster finish

Aluminiumdoor frameover sillflashing

Lining

Aluminiumsubframe

Front sealantafter planter

Paving level


47

Aluminium door details

It is good practice to step back theconcrete slab edge at door openings toavoid an awkward and vulnerable silloutside the door. This requires particularcoordination between the concreteplacer, ICF contractor and metal door andwindow supplier.

It is also advisable to allow for athreshold that is robust and easy to passover, this may require the aluminiumframe profiles to be modified.

SILL DETAIL

JAMB DETAIL

HEAD DETAIL

ICF block system.EPS stripped.Plaster smooth


FlooringTimber door & sill.Recess sill into slab.

ICF blocksystem

Exteriorfinishedplaster

Intermittenttimber blocking.Fix galv. nailsskew nailed totimber and castin concrete infill.

Interior finish.Return to reveal

Corner strip

Aluminiumflashing

Timber door &frame

Interior finish.Return to reveal

ICF block system

Cornerstrip

Exteriorplasterfinished

Intermittenttimber blocking.Fix galv. nailsskew nailed totimber and castin concrete infill.


PVC flashing.Plug & screwinto conc.

Slope toform dripedge

Timber door &frame

Sealant

SealantSealant &backing rod

Butyl rubber sillflashing

Paving level


48

Timber door details

The timber frame is set in the centre ofthe massive ICF wall. This massiveness isaccentuated by returning the interior andexterior wall finishes into the reveal.

Careful coordination of the rebate for thedoor sill will allow a near seamlesstransition from inside to out.

All timber must be separated fromconcrete by DPC.

HIGH THERMAL MASS DETAIL

HYBRID CONSTRUCTION DETAIL

150 10

0

Exterior insulationsystem

Interior lining

Exterior finish systemDPC

Paved G.L.

Unpaved G.L.

Granular hardfill

Internal plaster finish

ICF block system.Interior EPS removed

Extend plasterfinish to footing

Reinforced concretefooting

Sand blinding

DPC


Timber framing

Continuous topplate fixed @750max ctrs withcast in bolts

Internal plaster finish

ICF block system

Exterior finish system


49

Hybrid construction detail

It may be desirable to combine structuralsystems as this detail indicates.

The important coordination exercise hereis to ensure that the timber framing is setout to allow the exterior finishes tocontinue flush from the ICF to the ExteriorInsulation Finishing System.

Note that the acoustic separationprovided by this timber framed floor isminimal.

Refer to the manufacturers literature forguidance on details that can improveacoustic performance.

High thermal mass detail

To overcome the thermal mass beingseparated from the internal space, it ispossible to remove the inner skin of ICFto reveal the concrete cores which canthen be plastered smooth to a finish thatis tough and durable.

SILL

HEAD

FOUNDATION

Timber reveals

Timber plate

Timber block

Internal fininsh

ICF block system

Tile sloping sill on 9mmfibre cement board onshaped timber

2 coats waterproofingmembrane


Aluminium window joinery

MS angle

Concrete masonry veneer ICF Block system

Aluminium flashing

Lining

Timber blocks. Fix galv. nailsskew nailed to timber & cast inconcrete infill.

Aluminium Window section withTimber Reveals

Veneer ties

Veneer ties extendingto vertical reinforcing

Cavity

Waterproofing membrane


Skirting & lining on intermittentfixing blocks

Internal finish

DPC

Sand blinding

Granular hardfill

Unpaved G.L.

Paved G.L.

Weep holes @ 800 crs

Cavity

2 coats waterproofingmembrane

Fibre cement sheet

Veneer ties extending tovertical reinforcing

Strip outer face of ICF

ICF block system



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It is possible to combine the excellentdurability and appearance of concretemasonry with the insulating qualities ofICF.

Waterproofing of the ICF outer face (in thecavity) is usually by a painted on systemsuch as bituminous paint.

The veneer (10 series) must be secured tothe structure by way of ties that areembedded in the concrete cores. This willrequire special attention to coordinationof ties with anticipated joints.

PARAPET

PARAPET

OVERHANGING VERGE

Ceiling batten

Rafter fixed to block with galv.bolt.

External finish

Steel reinforcing

Plywood base fixed to timber framing

Stringer fixed to block with galv. bolt.

Fascia

Building paper

Internal finish

DPC

DPC

External finish

Slope top of blocks in towards gutter.

Purlins onedge

Slope top of blocks in towards gutter.

Joist hanger

Flashing

Soffit

ICF block system

ICF block system

ICF block system

Reinforcing

Fix Butynol into chase in block, fix 90PVC angle cap to Butynol edge andseal in place. Finish Plaster downonto PVC angle

Fix Butynol on Plywood base to formgutter as shown

Apply sealant in chase then insertflashing.

Flashing

Roofing on purlins

Roofing

Timber rafter

Ceiling batten

Top plate embedded in ICF block.12mm Galv. bolt cast in Conc.

Insulation


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Roof details

Providing adequate and appropriatefixings for additional structural orarchitectural elements is critical. All threeof these details show typical fixings thatmust be allowed for.

Ensure adequate provision is made foroverflow should the primary system blockup. Internal gutters should be wide toallow ease of service and deep enough toaccommodate the expected runoff.

Timber Decking

Linings

Insulation

Aluminium Door section

Linings

Precast concrete slab

Reinforcing

ICF block system

Timber decking

Insulating plasterboard lining

Waterproofing membrane onConc. roof

Construction joint

Precast concrete slab

External finish

ReinforcingICF block system

FALL

Construction joint

WaterproofingMembranecarried upunder doorjoinery.

Reinforced Conc. topping

Fix waterproofing membraneinto chase cut into wall. Fix90 PVC angle cap toMembrane edge and seal inplace. Plaster down ontoPVC angle


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Terrace details

Raised terraces over living space are nowvery popular. Detailing of terraces pres-ents a number of challenges in

allowing ease of transition inside vs.outside

preventing water ingress at dooropenings

preventing water ingress at walls,especially at construction jointbetween slab and upstand

A step in raised concrete floor levelsrequires a special coordination effort toensure continuity of structure andsupport of the concrete flooring systems.


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Services

ICF present the easiest way of reticulatingservices of any concrete structuralsystem.

Services up to 40 mm, depending on thethickness of the polystyrene face, can beaccommodated by cutting away a chase.Generally these services must be securelyfixed to the concrete core by way oflamps and tappets. The chases must thenbe covered over by the finishing process.Plasterboard is generally able to spanacross the gaps but care must be taken tonot place a sheet joint on the chase.

Plaster systems will require a bandage.The supplier should be contacted fordetails.

Services can also pass through the wallsbut positions and sizes must beapproved by the manufacturer.

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Precast Concrete

General . . . . . . . . . . . . . . . . . . .57

Design . . . . . . . . . . . . . . . . . . .58

Specification . . . . . . . . . . . . . .60

Construction . . . . . . . . . . . . . .62

Details . . . . . . . . . . . . . . . . . . .65

Precast Concrete

57

The development of concrete precasting techniques in thiscountry has allowed reinforced concrete to competefavourably with other forms of construction. Curiously ithas not made a serious entry into the residential constructionmarket until the past 10 years. This later period has coincidedwith the development of proprietary self insulating precastsystems. Details of such systems are presented in this section butthere is also plenty of scope for applied insulation systems.

Concrete precast methods were pioneered in the US early in the20th century. The New Zealand industry is well developed andgenerally acknowledged as a world leader. There are good suppliesof the raw materials and technology in most parts of the country.

Precasting, whether done in factory conditions or on site, offersthe opportunity to control the quality to a high standard.

Advantages of precast concrete construction systems include thefollowing:

quality control the quality is better able to be controlled bycasting multiple units in the same mould, by casting walls flatrather than standing upright and through the ability to bettercontrol environmental conditions.

lower costs for the reasons noted above.

finishing options inherent in solid concrete construction

interesting shape and texture possibilities

speed of construction with off site production the panelsand other precast elements can be made while the site isbeing prepared. It is possible to set up a house in two dayswith an experienced crew.

The Pascal Housein Auckland byCook, Hitchcock& Sargisson.


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Precast flooring systems are ideal for use in a concrete home. Anumber of different flooring systems are currently available inNew Zealand. These proprietary systems have been developed forcommercial buildings, but are also suitable for the span andloading demands that can be anticipated in residentialconstruction. Suppliers generally offer design services which canbe incorporated into the overall structural design philosophy.These flooring systems can be categorised as follows:

flat slab

hollow core slab

rib and infill

steel tray permanent formwork

The systems all offer excellent stiffness, durability, acoustic andthermal performance, they can be planned to includepenetrations and openings and are cost competitive with timberflooring systems. They are also not prone to annoying squeaksthat can occur with timber floor systems.

design

As with in-situ concrete (refer to In-situ section), there arechoices to be made with respect to the following:

Surface Texture

There are many opportunities with precast concrete to createinteresting surface textures. Finishing techniques for the formed(underside) face are described in the surface finishes section. Thescreeded face (topface) generally becomes the second side orback. Texture options include:

exposed aggregate

acid etched

ground and polished

board formed

Colour

Concrete used in precast work can be coloured. This can beachieved with colour throughout the mix, or alternatively, it ispossible to place coloured concrete on the exposed face withstandard concrete behind.

Panel or unit format

The size and layout of individual panels is essentially limitless.However, there are some practical limitations. Typical parametersthat may dictate panel size are:

the area available for casting (when casting on site). This maybe an area of a floor slab or a separate temporary casting slab.

efficient repetitive use of special moulds

site access

capacity of lifting equipment or transport

the positioning of panel joints relative to openings.

Precast concrete systems include floor units in addition to walls.

Combining surface finishes can help breakdown the scale of a building.

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59

there are also aesthetic considerations to be made. Panel sizewill dictate joint set out and affect scale, texture and surfacearticulation of the house design.

The designer must also take into account panel thickness. Thereare structural aspects to consider for both transport andpermanent positions. The designer may be particularlyinterested in panel thickness when considering opening revealdepths and thermal mass benefits. Commonly panel thicknessvaries between 100 mm and 150 mm.

Jointing Details

The width and depth of joints between panels, as well as theprofile of the panel edges, must be considered by the designer.Examples of weatherproofing details are shown to the left, themost commonly used detail in the face-sealed joint. Otherconsiderations include how connections are made betweenpanels, to the floor, and to any other structural or non-structuralelements. These deliberations will most certainly include thestructural designer for the project. Options include expressingplates and bolts, countersinking and plastering over weldedplates or to conceal entirely by using pressure grouted tubes.

Edge details

Individual panel edges, especially when exposed to view, are adesign opportunity. These considerations are best made in thecontext of the joint design but should also look at corners,openings, top edges and junctions to other materials. Panel edgesare vulnerable, especially during placement of panels. It is verydifficult to successfully cast a crisp 90 corner on any concretepanel, it is therefore advisable to chamfer the corners.

Typical panel jointing details.

Sandwich constructionallows concrete panelto be left exposedinside and out.


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Insulation and weatherproofing

Although more waterproof than other forms of concrete, such asmasonry, precast concrete is still permeable to water and requireswaterproofing. Waterproofing can be achieved by application ofacrylic paint systems, which can be applied direct or as part of aplaster finish system. Veneer cladding systems can also providethe required waterproofing. Insulation can be placed on theexterior, interior or between skins of concrete. This latterstrategy has given rise to a number of specialist panel systemswhich allow all the positive aspects of concrete to be realisedwithout compromise. These systems make use of a polystyrenesheet, between an outer skin or veneer of concrete, and an innerskin which typically acts as the structure. The two faces are heldtogether by thermally non-conductive ties which are cast intoeach wythe.

specification

Designers have a choice to make between proprietary sandwichconstruction and the traditional forms of precast. If the choice isto use a proprietary system, the specification should be genericto allow a range of proprietory systems to be evaluated.

A proprietary system supplier may be required to provideProducer Statements, guarantees and constructionrecommendations.

It may be prudent to require the contractor or precaster toproduce sample panels for evaluation of such aspects as surfacefinishes. Work should not be allowed to proceed without thedesigners approval of these samples.

The Standards which apply to precast concrete construction areas follows:

NZS 3101:1995Concrete Structures Standard The design of concrete structures

NZS 3104:1991Specification for concrete production High grade and special grade

NZS 3109:1997Concrete construction

NZS 3112Methods of test for concrete

NZS 3113:1979Specification for chemical admixtures for concrete

NZS 3114:1987Specification for concrete surface finishes

NZS 3402:1989Steel bars for the reinforcement of concrete

NZS 3121:1986Specifications for water and aggregate for concrete

NZS 3421:1975Specification for hard drawn mild steel wire for concretereinforcement

Sandwich construction detail.

Joining plate can be left exposed as a design feature.

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NZS 3422:1975Specification for welded fabric of drawn steel wire for concretereinforcement

Materials

All materials should be procured from a dependable source.

Where appropriate, the builder must ensure that quality recordsare kept for all precast concrete work. These records must beeasily retrievable should they be required.

FormworkFormwork requirements are detailed in NZS 3109.

Reinforcing steelTo comply with NZS 3402, NZS 3422.

ConcreteReadymix concrete to the specified compressive strength and tothe requirements of NZS 3104.

Special aggregates For special finishes specify the aggregate type, colour, size, rangeand depth of exposure. All aggregate to comply with NZS 3121.

Lifting inserts Proprietary lifting devices are preferable. It is important tomatch the lifting inserts with the apparatus that will be used forlifting and the processes that will be adopted for casting andlifting.

Steel connection platesIt is recommended to galvanise any mild steel fixings that will beexposed to weather.

Workmanship

Construct formwork in the configuration necessary to producethe required set out and detail of panels. Pay particular care toedge details.

The construction and casting of panels should be carried out bytradesmen experienced in precast concrete construction.

Place and cure concrete to produce the specified finishes andtolerances. Curing should be carried out for at least 7 days.

Surface finishes shall be as specified by the designer and asdefined in NZS 3114.

Allow to cast in all items required for fixings or services. Thisrequires coordination between the trades before the panels aredesigned and cast.

The installation should be carried out by contractors experiencedin precast construction. All necessary components such asgaskets, sealants and flashings should be supplied and fitted.

Rigging and lifting must be done using the lifting pointsspecified. Take care not to knock or drag panels along theground.

Panels must

Residential Concrete

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