1 Construction Systems 1 ALTERNATE CONSTRUCTION © Unitec New Zealand R. Kelly P. Faumuina Photo...

1

Construction Systems 1

ALTERNATE CONSTRUCTION

© Unitec New Zealand

R. KellyP. Faumuina

Photo courtesy of gmik.wordpress.com

This lecture explores some other forms of alternative residential construction that can be used in New Zealand, but which are outside of the scope of NZS 3604.

The forms of construction covered are:

IntroductionINTRODUCTION

Autoclaved Aerated ConcreteInsulated Concrete FormworkEarth Construction

General

Autoclaved Aerated Concrete is madewith cement, lime, water and sand.

It uses no aggregate larger than sand.

Photo courtesy of hebelaustralia.com.au

Autoclaved Aerated Concrete

AUTOCLAVED AERATED CONCRETE

Photo courtesy of celcretecladding.co.nz

General

The sand is ground to a fine powder.

A small amount of aluminium paste is added to the mixture.

Photo courtesy of hebelaustralia.com.au


Photo courtesy of celcretecladding.co.nz

General

Aluminium reacts withalkaline elements in thecement and lime causing themixture to aerate, filling withmillions of tiny finely dispersedbubbles.

When the concrete is partially cured, it is stripped from the mould, cut into blocks or panels and steam cured in an autoclave under high pressure and temperature.


Photo courtesy of bridgat.com


General

The result is concrete that is only about one fifth of the weight of conventional concrete.

Photo courtesy of bridgat.com

Photo courtesy of cement.org

http://www.youtube.com/watch?v=QmL-Xz-p5fY

http://www.youtube.com/watch?v=QmL-Xz-p5fY

HEBEL

Autoclaved aerated concrete was invented in Sweden in the 1920’s and Josef Hebel began commercial production of Hebel Blocks in Germany in 1940.

Hebel was usedExtensively in there-construction ofpost-war Germanyafter World War II


Photo courtesy ofpushpullbar.com

HEBEL

Hebel is a lightweight AAC building material which is factory cut into blocks, panels, and special elements for a wide variety of building applications, both load bearing and non-load bearing.

Hebel products includepanel claddingblock constructionstructural flooring fences


Photo courtesy ofpushpullbar.com


HEBEL

So what are the advantages of using Hebel?

Check out this brochure…………..

http://www.candslightweight.com.au/

http://www.candslightweight.com.au/

Finishes

Finishes for Hebelconstruction can rangefrom simple acryliccoatings to high buildrenders and textures,depending on theaesthetic requirementsof the project.

The most common is the smooth, Monolithic look.


Proprietary system used to build concrete structures quickly.

A system where hollow expanded-polystyrene blocks are fitted together like Lego and concrete is poured into the spaces.

Check out this video

http://www.youtube.com/watch?v=ywGLyvxdoQI

Insulated Concrete Formwork (ICF)

INSULATED CONCRETE FORMWORK




General

The polystyreneFormwork is left in place.

It is strong and durable,and in some cases, it isreplacing conventionallightweight construction.

It integrates insulation with the strength and durability of concrete


Photo courtesy of worldhousedesign.com


General

Reinforcing steel is added as needed before the concrete is poured.

This gives a solid concrete wall with polystyrene insulation on both sides.


General

Walls are plastered orLined inside and outside toprotect the polystyrene andImprove appearance.

ICF must also be properlyclad to keep water out.

There are several ICF systems available in New Zealand, each offering different features.

Photo courtesy of ecohomeswa.com.au


General

Wikipedia also provides additional useful information.

Click on the link below…

Polystyrene formwork being cut on siteSource of image unknown

http://en.wikipedia.org/wiki/Insulating_concrete_form



Cost

Initial construction cost of ICF may be higher than conventional lightweight timber construction.

But benefits will be:

Increased sound and thermal insulationImproved durabilityAesthetic appeal of solidity.


Click on this documentfor some interesting comparisons

Information courtesy of concreteconstruction.net

Strength

With ICF construction, the strength is provided by a reinforced solid concrete wall between the layers of expanded polystyrene.


Durability and Weathertightness

ICF is as durable asconventional concrete.

It can be low maintenance.However, the polystyrene needsto be protected from physicaldamage and from ultravioletradiation. ICF is weathertightso long as it is properly clad.


Photo courtesy of blog.seattlepi.com

Passive Design

ICF provides good thermal insulation –a standard ICF wall will provide enough insulation to meet or exceed Building Code requirements without any additional insulation.

ICF provides good sound insulation.

ICF’s concrete core is good at storing heat, but can only be used for this if the internal polystyrene layer is removed.


Photo courtesy of sustainableconcrete.org.uk

Photo courtesy of gologichomes.com

Topography and site impact

ICF can be used to build single and multi-storey buildings, but would be better suited for level sites.


Climate

ICF can be used in all climate zones.

Its high insulation properties make it suitable for both cool and hot climates.


Milbrook Resort HotelPhoto courtesy of travelwizard.com

Villas in SpainPhoto courtesy of

icf-spain.com

Earth construction involvesthe use of soil as the mainingredient in the formationof walls for buildings.

Other ingredients such assand, silt and clay are alsoadded.

It is a natural, strong,durable and healthy building material which can be used in most conditions, provided it is designed and built to provide protection from rain.

Earth ConstructionEARTH CONSTRUCTION Photo courtesy of eartharchitecture.org

It has been a very commonconstruction material allover the world forthousands of years.

Earth ConstructionEARTH CONSTRUCTION

http://www.youtube.com/watch?v=0RnJZq9rbL8&feature=related

Photo courtesy of eartharchitecture.org

Click on this link for a video of rammed earth construction ……FF if it gets boring! (3:30secs)

http://www.youtube.com/watch?v=0RnJZq9rbL8&feature=related

Foundations

The walls are supportedupon engineered concretefootings.

Vertical reinforcing steelextends from these footingsthrough the earth wall into the bond beam at the top of thewall.

A successful earth construction project starts with proper foundations

Photo courtesy of earth-construction.com

Earth Construction

Foundations

Conventional concrete slabor strip footings are generallyused, the size and shapeof which is subject tosoil conditions.

A DPC is laid betweenthe concrete and wallsto prevent rising moisture.

Earth Construction

A successful earth construction project starts with proper foundations

Photo courtesy of earth-construction.com

Durability and weathertightness

Earth buildings can last a very long time and generally require very little maintenance as long as they are not exposed to driving rain.

To provide protection, overhanging eaves or verandahs are needed.

New Zealand Standard for earth buildings specifies the size of the overhang for each part of the country. Photo courtesy of

au.totaltravel.yahoo.com

Earth Construction


Some earth buildings have an exterior coat of plaster to help with weathertightness.

Photo courtesy of au.totaltravel.yahoo.com

Earth Construction

Passive Design

Earth walls:

Provide poor thermal Insulation but good sound Insulation

Absorb heat during the dayand radiate it out as thetemperature drops at night.

No harmful emissions

Breathe, helps to control humidity.

Photo courtesy of ecobuild.co.uk

Earth Construction


Earth walls are very heavy andonly work well on stable sites withgood foundations. ClimateEarth buildings can be suitable forall areas of New Zealand, providedthey are protected against dampand wind-blown rain.

Earth Construction

Earth construction in MozambiquePhoto courtesy of eartharchitecture.org


Photo courtesy of inhabitat.com

A house in Arizona with large roof overhangs and massive rammed earth walls which help keep it cool in a desert environment.

Earth Construction

Finishes

Earth walls generallyrequire no additionalfinish, but should beprotected by a breathingtype sealer.

Walls can be surfacetextured to createdifferent finishes andcan also be very easilyrendered, plastered orpainted.

Earth Construction

Photo courtesy of archfoci.com

Cost

Costs for an earth-builthome are comparable toconventional construction.Materials are inexpensive,but the process is verylabour intensive.

It is also more cost effectiveto have a source of suitable earth on-site.

StrengthIn general, earth buildings are very strong in compression, but not so strong in tension.

Earth Construction

Photo courtesy of greenupgrader.com

The types of earth constructionwe will consider are:

Rammed Earth

Poured Earth

Mud Brick

Pressed Earth

Earth Construction

Photo courtesy of engeyedesignteam.wordpress.com

Photo courtesy of arquitecturasdeterra.blogspot.com

Rammed earth walls are constructed byramming a mixture of earth, with gravel,sand, silt and clay, into place betweenformwork.

The formwork is usually made of adouble layer of 20mm ply locked togetherwith bolts at close spacings.

Earth ConstructionRammed Earth

Ramming is done with manual or mechanical rammers

As each form is filled,another form is placedabove it, and the processbegins again.

This is continued until thedesired wall height isachieved.

Forms can be stripped off as soon as the form above is begun, as the compressed earth wall is self-supporting immediately.


Photo courtesy of eartharchitecture.org

External walls are usually 300mm thick,and internal walls may be 20mm.

Curved walls are possible but need moreexpensive formwork.

Walls are rammed in layers of approximately100mm, and the formwork is removedimmediately after compacting to revealthe finished surface of the walls.

Once all the walls have been completed a concrete bond beam is cast, linking the top of the walls together.

Earth ConstructionRammed Earth Photo courtesy of

r0dman.com

Joints and Connections

Walls are built in panelsof approximately2 metres in length.

When a wall consists ofmore than one panela rebate is built into theend of the first wall.

The second wall then moulds into this to lock the walls together for lateral stability.

Earth ConstructionRammed Earth Rammed earth house under construction

Photo courtesy of dab.uts.edu.au

Timber Framing and Finish Work

Once the earth wallsAnd concrete work arecompleted, conventionaltimber framing is thenused to construct otherelements of the project,such as roof,interior walls andmid floor framing.


Photo courtesy of carriesdesignmusings.blogspot.com

Rammed Earth Wall at Ground Floorwith Timber Framing at First Floor


Rammed Soil CementHouse Australia


Rammed Soil Cement Earth Wall, NZ


Poured earth walls areconstructed using a wetmixture similar to rammed earth,but 10% cement added, andpoured into formwork.

Once the mixture is dry, theformwork is removed andmoved up to form another layer.

To prevent cracking, alternate sections are completed and then the gaps are filled in.

Earth ConstructionPoured Earth Photo courtesy of

pouredearthhome.blogspot.com

Earth ConstructionPoured Earth

Photos courtesy of pouredearthhome.blogspot.com

Mud bricks, sometimes known asadobe blocks, are made from apuddling (or wet) mixture ofstiff mud, with cement added as astabiliser and straw or other fibresto reduce cracking.

The mixture is shovelled into asimple mould, pressed into thecorners and allowed to set beforethe mould is removed.

Earth ConstructionMud Brick (Adobe)

Photo courtesy of lesteves.wikispaces.com

Mud bricks are laid similarly toconventional masonry, but with athick layer of mud mortar betweenthem.

This mortar is also rubbed overthe walls to fill in any gaps andcracks.


Photo courtesy of lesteves.wikispaces.com

Finishes

Similar to other forms ofearth construction, but inaddition the walls canalso be whitewashed toleave the outline of thebricks.


Photo courtesy of architecturenews.co.cc

Mud Brick Walls Whitewashed


Similar to mud bricks, except adry earth mixture is used whichSaves the drying time needed formud bricks, and gives a moreuniform size.

Earth ConstructionPressed Earth

Photo courtesy of freshomedesign.com

Straw bale constructioninvolves the use ofdry bales of straw arewhich are stacked likebricks to form a wall.

The bales are tightlywired together and thenplastered, but the plastermust allow the bales tobreathe in order toprevent moisture build-upwhich causes rotting.

Earth ConstructionStraw Bale

Straw bale walls before plastering

The plaster is often limeor earth-based.

The bales need to bestacked tightly on acontinuous concretefoundation with a DPCunderneath to keep thebales clear of the ground


Straw bale walls before plastering

Straw bale walls after plastering, a similar look to a stucco or adobe wall.


Cost

Straw is normally a waste product and can be a cheap building material.

It consists of stalks and leaves of various cereal crops, without the seeds.

Straw Bale ConstructionStraw Bale

http://www.youtube.com/watch?v=LZABqaEsrLM

Click on link below for straw bale construction videoFF to 60secs

Photo courtesy of flickr.com

http://www.youtube.com/watch?v=LZABqaEsrLM

Sustainability

Straw is produced as a bi-product of an existing agricultural industry and can be produced every year

Straw Bale

Photo courtesy of silive.com

Straw Bale Construction


It is essential that the straw does not get wet during or after construction. It will rot.

Photo courtesy of armofthespiral.com

Straw Bale


Straw bale wallsmust have:

a damp proof membraneunder the straw

a roof with very wideoverhangs

a good plaster system to keep moisture out - the coating must be crack-free, and the plaster needs to be painted

Photo courtesy of builditgreen.co.zaStraw Bale


flashings at doors,windows and junctions –flashings are essentialbecause sealantsdon’t work well with straw.

Straw Bale Photo courtesy of builditgreen.co.za


Passive designStraw bales have excellent thermal insulation properties since they are thick, trap air and do not conduct heat well.

They are also very good sound insulators. But they are not good at trapping and storing heat.

Photo courtesy ofebsteam.com.au

Straw Bale



Straw bale construction is most likely to be used for single-storey buildings.

Straw Bale


Because of the need for aconcrete footing, a flat siteis probably better for astraw bale building.

The site must bewell drained.

Straw bale is not generallypractical for asmall urban site. Photo courtesy of en.wikipedia.org

Straw Bale


Climate

Wind-driven rain makes demands on design and construction of straw bale houses, making it unsuitable for areas of high wind and heavy rainfall.

Straw Bale


1 Construction Systems 1 ALTERNATE CONSTRUCTION © Unitec New Zealand R. Kelly P. Faumuina Photo...

Documents

Transcript of 1 Construction Systems 1 ALTERNATE CONSTRUCTION © Unitec New Zealand R. Kelly P. Faumuina Photo...