Asignment 01 F103TEC- 2011

The College Of Estate Management Building Technology 01

University of Reading Bsc. ASSIGNMENT 01 Module Code: F103TEC

Answer for question 01a

House 10 is a terraced house which is part of large terrace of six units in one

raw, including some Victorian type architectural features such as; high pitched

roof made of slates, high gable walls in front and rear elevations, Big Sash

Windows (open by sliding the window up), Outer brick walls, gable wall end

with corbelled brick work etc.

• High pitched roof

The high pitched roof made of interlocking fibre cement slates is plays a major

role for the better view of the house and provide to allow water runoff and a

deterrent to frozen perception such as snow and ice. The snow and ice will slide

down the slates as it melts instead of penetrating the roof underneath the

slates. The roof fully constructed with timber frames including purlins, ridge

plate supporting timber rafters. The plain ridge tile has been fixed to cover the

ridge and top edge of the slates in top raw to avoid the water leaking through

the slates. There is eves exposed to the elevations and the joining of the gable

walls with roof has fixed with flexible metal flashing to cover the water leak

through the joint. The wooden facia board is fixed to the bottom end of the roof

for facilitate the fixing of gutters.

• Gutters and down pipes.

It assumes to be half round UPVC gutters are installed with UPVC down pipes

and appropriate fittings. In front elevation, the main roof water has collected to

the high level gutter line and goes through the running outlet and down pipe

directed to the low level gutter line. Both the high and low level, collected

water again goes away from valley gutter running outlet through the down

pipes fixed to the both corners near to roof valley to the drain manholes

situated in the ground. Architecturally the positioning of down pipe is

symmetrical to the house 10 and 11 elevations and positive effect to the

appearance.

• External walls.

The external wall of house 10 consists of the load bearing cavity walls with

block work inner leaf and brick outer leaf. For the external features, the outer

skin of the brick work is considered. The type of the bond identifies as common

stretcher bond. The width and profile of the mortar joint has impact on the

appearance of brick work. The weathered mortar joint is more appropriate.

Wall ties in cavity wall achieve the strength and the prevention of water

penetration to the inner leaf of the wall. The galvanized steel lintels on the top

of window and door openings are used. The door and window openings are

symmetrical in the front and rear elevations of house 10 and 11. The wall ends

are seems to be moulded. The height of the external wall is match with the

appearance of the house and gable walls.

K.P.Prabath Chammika Yasapala1003754

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Continue Answer 01a….

• Gable walls.

The high gable wall with outer skin brick work in front and rear elevations are

added a gigantic view of the house and reflects the typical characteristic of

Victorian house. The top end of the gables are decorated with coping brick work

and separated the ordinary stretcher bond outer skin brick work with a grove

for damp proof course and the end of grove decorated with moulding. The door

and window openings are decorated with a thin groove or moulding for better

appearance. The high supporting cross walls (gable walls) are appeared to be

finished with outer skin brick work and top pre-cast concrete coping.

• External windows.

Big Sash windows are appeared in front and rear elevations made by

aluminium powder-coated frames with double-glazed units (open by sliding the

window up). The double glazed will reduce the thermal effect and aluminium

frame is more durable and easy for the fabrication. The standard sill heights

are maintained in ground floor and the large window achieves the lighting and

ventilation requirement as well. The top moulding disturbs to the flow of rain

water along the window sash and the sill is active to prevent the water flows on

the wall surface under the window.

• External doors and porch area.

The main entrance door, store room door and kitchen out door are the main

external doors used as access to the house and store room made by wooden

framed with doubled glazed units. The size of the main entrance is larger than

the other internal doors. The providing of top light and double glazed unit is

also maintaining a weather barrier. The threshold and weather mouldings are

protect the door from the external environmental effects especially from the

water. The small porch is available on main entrance and helpful to cover the

entrance to serve as a shelter for weather effects such as rain, direct sunlight

and wind. The floor assumes to be finished with mat finish tiles in the porch

area.

• Ground elevation.

The step down of ground elevation from house 09 to 10 has added an

attractive architectural view to the front and rear elevations and highlighted the

different roof elevations with high supporting cross wall helps to identify the

separate units of 09 and 12 and be assumed that the original ground elevations

with gradual slope down the site towards south east has well utilized.

• Landscaping.

It seems to be a wooden fence has separated the units and easy access is

available from the roads. Provision for parking area is located in front of the

house and the small gardening area is available.


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Answer for question 01b.

RIDGE DETAIL

DETAILS OF PITCHED ROOF

Source: CEM –Building Technology 1


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DETAIL OF RAIN GUTTER


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Continue Answer 01b…

DETAILS OF EXTERNAL CAVITY WALL


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Continue Answer 01b….

DETAILS OF GABLE WALL


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DETAILS OF ALUMINIUM WINDOW

Source: Esmond Reid – Understanding of Buildings.


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DETAILS OF DOOR FIXING



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Answer for question 02

The roof, External walls, floor, doors and windows are the main exteriors of the

house. This envelope is the environmental separator, generally between the

inside and outside of a building including the ground. The proper designing,

construction techniques, proper materials and proper maintenance can increase

the durability and longevity of the building and as well as the durability of

exteriors. The durability of the material which is used for construction is very

important for the life span of the building. A building's lifespan has mostly

depended on the structure of the building and the exteriors should have to be

tightly covered the structure from the effects of external environment. The

effective control of the following external climatic or environmental factors by

the exteriors achieves the durability and longevity of the house.

• Water/moisture

Water /moisture enters building’s exteriors due to condensation, from rain

or melting of snow and is responsible for the swelling and rotting of some

organic materials such as wood and the corrosion of metals. It is involved in

the freeze-thaw deterioration of porous materials.

• Air pressure/ wind

The wind will decay the surface of the materials and the physical damages

by removal of part of building and wind will cause air leakages. Air leakage

is a major cause of problem in exterior walls, cause dampness by driving

moisture into building fabric and excessive heat loss from the interior.

• Solar radiation

Ultraviolet radiation from sunlight affects the durability of organic materials

such as polymers, wood and bituminous materials.

• Temperature

Due to the variation of temperature, building materials change volume and

if change in volume is not allowed for in the form of movement control

joints and it will form cracks and thereby affecting the durability of the

component.

Roofing system

The proper pitched roof determines the durability and longevity of the house

with appropriate water proofing system. The selection of pitched roof (Pitch

around 350 - 400 minimum) and the materials such as; the roof covering

materials, wooden rafters, battens, damp proof membrane, gutters, down pipes

and fascia board has to be appropriate for the design function, detailing for the

application and the proper installation is essential. Especially for the rain, roof

is the hardest tested surface in wet weather. Water proofing is necessary for

the pitched roofs with continuous DPM and the edges of the high supporting

cross walls must be covered with flexible metal stepped flashing.


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Continue Answer 02….

The overlapped fibre cement slates must be nailed to battens for the

unmovable position and the curvature determines the broken capillary path.

The ridge tiles must be detailed and installed properly overlapped with the top

raw of fibre cement slates. The treated timber has to be used for the roof

structure and it does not attacked by uncontrolled damp and fungal attacks.

If there is no any water leakage to the inside of the house from roof means the

proper material selection, design and workmanship achieved. The proper and

regular maintenance is essential for roofs and concentrate for the collection of

the rain water and got away immediately through the down pipes. If it were

just left to be shed from the edges, it would soak and damage the external

wall. Eve of the roof helps to cover the external wall from direct storm water.

(Refer Figure 2.1 in Appendix A for details of pitched roof water proofing).

External walls

The external walls involve to providing the environmental control between the

external and internal climate of the house and is required to support the

imposed and wind loads of the roof and floor and transfer its own combined

loads safely to the foundation. The external walls play a major role for the

durability and longevity of the house. The selection of appropriate materials

according to the climatic effects, construction methods to resist water

penetration through the envelop, controlling of expansion of walls (maintaining

expansion joints and contraction joints), controlling of capillary action on the

external surface of the wall and detailed solution for the erosion are sought to

be address.

The walls can be segregated as the permeable, semi permeable and

impermeable. For this construction, the semi permeable is used as the cavity

wall with block work inner leaf and brick outer leaf. Water penetrates through

the bricks, the cavity allows flowing down the water and coming out through

the bottom weep holes. The non corrosive ties must be embedded within the

horizontal mortar of the joint in order to provide adequate restrain to each leaf

of the wall. The type of bond is stretcher and the type of mortar joint is

affected by the variation of temperature. So the allowable expansion is

necessary. The providing of insulation is for the thermal comfort inside the

building and the block work must be properly constructed as per the

performance requirements. The opening of the walls must be properly sealed

after the fixing of door or window to avoid water penetration through these

gaps. Mastic fillers should be used. The maintenance of the external brick face

gains the durability of the external wall. Especially the mortar joints should be

maintained and inspected. The top of walls should be properly covered in Gable

walls and with cobbled end.


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Solid ground floor slab

The type of the ground floor is very important part of a house for the durability

and its longevity. The ground bearing insitu concrete slabs and suspended

timber floors are common in small house construction. For both, the damp

proofing system, firm base and the finished level should be properly detailed

with appropriate construction method. To address the heat loss, insulation

material can be placed on the damp proof material.

Removing of top soil and filling with appropriate filling material to the required

thickness with full compaction using mechanical hammers up to the dry even

top surface for the laying of concrete slab. The thickness of hardcore and the

concrete slab is minimum 100-150 mm. The greater mass of concrete will offer

a greater resistant to rising moisture. The ground water table must be

considered when the slab designing and the proper detailing is sought for the

damp proofing system. The more thickness slabs, (more than 100 mm thick)

the reinforcement mesh is required to avoid the shrinkage due to weak subsoil

condition. For the insulation can be placed to reduce the heat loss either before

casting the ground slab on the 50 mm thick concrete screed or on the ground

slab covered with 50 mm thick screed. Both methods can be used and after the

casting of ground slab. We have to select the appropriate and economical

system for the above application.

(Refer figure 2.2 and 2.3 in Appendix B & C for the details of ground bearing

concrete slab with damp proofing system)

Doors and windows

The openings must be fulfil the following functions such as; access, weather

protection, appearance, ventilation, lighting, view, privacy and security.

Construction methods used to resist water and wind penetration through door

and window opening is essential for the durability of the building. The wooden

door frame or aluminium coated window frame fixing to brick work, threshold

and sill details, the seal between door, window frame and glass and draught

excluding devices can be fitted in the gap to eliminate the flow of air is

essential for proper detailing of door and window. Double glazed units will

reduce the heat and sound from the external environment as well. Weather

protection must be provided for timber doors by non absorbent finish and a

weather board fitted across the bottom. For windows also the same applicable

for weather exclusion. It is important to reduce the water streaming down the

window face. Head moulding and window setback within the wall depth help to

fulfil the above requirement.


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Answer for Question 03

For the determination of form and layout of the building, consideration of

geographical, climatic, geological and environmental factors is necessary.

These are the external environmental influences.

The selection of appropriate location, type of the building, shape of the building

and other requirements such as; selection of appropriate materials, type of

foundation etc. are mostly depending on the environmental influences.

The following environmental influences should be considered for the

determination of the building’s form and layout.

• Air and pressure

• Wind pressure (natural ventilation)

• Daylight

• Sunlight and passive solar gain

• Sound

Air and pressure

The selection of appropriate location for the better living, the air purity and the

altitude sought to be considered. Avoiding of air polluted areas and higher

altitude (higher elevations) should be considered. The distance between such

as industrial areas and thermal power plants hectare to be care when the

designing of residential complex. For the breathing process, the contain of

oxygen in fresh air should be as per required percentage (21%). Especially the

carbon dioxide percentage (0.03%) has to be monitored because it causes the

global changes and threat to the whole living creatures. The blood can function

normally at atmospheric pressure at sea level. So the healthy altitude should

be considered (250 – 750 m from sea level).

Wind pressure (natural Ventilation)

Wind direction and the wind speed (strength) are acquiring the natural

ventilation for the building. For the satisfactory standards of air purity and

comfortable atmospheric condition within a building the above two properties of

the wind is highly required.

For the determination of form and layout of a building, the following

characteristics of wind should be considered.

• Wind pressure.

• Aspiration

• Perflation

• Stack effect.


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Wind Pressure

The front face of the building can be gain pressure due to wind (windward side)

and other sides gain the suction (leeward side) effect. The centre of the face

has high pressure and the edges of walls comparatively low. Suction is

higher in edges and corners. Also roofs are more effected due to above high

speed wind currents. The pitch of the roof is an important factor in windy

conditions. The low pitch roofs below 150, there is maximum suction and

negative pressure and the pitch above 350, positive pressure on windward

direction and suction on leeward side. So the determination of pitch of a roof in

windy condition is highly important for the stability of a roof.

Aspiration

Wind current passes a building through the right angle across the top of a

ventilation shaft, air is move up from the shaft and fresh air fills the rooms

below. This is additional to the upward movement of warmed air when fire is

burning.

Perflation

Perflation can be maximized with identification of correct wind direction of the

location. The cross ventilation is gaining more benefits of natural ventilation.

Wind will enter to the building by windward direction through openings or inlets

and flow through the outlets in leeward direction due to suction effect. The flow

of air is diverted up and over the building and side windows can be either inlets

or outlets. The windows are used to control the volume, velocity and direction

of air flow and must be capable to adjust according to the requirement of the

ventilation.

Stack effect

Stack effect also replace the fresh cool air into a building as natural ventilation.

Low dense warm air displaced by cool heavier air as a vertical current and

enters through the openings at low level and warmer air will escape through

the openings at higher level. This process is highly depend on the speed of air

movement, temperature difference between inside and outside of the building,

level difference of higher and lowers openings and the area of the openings.

Daylight

Day light is the “natural lighting”, the sky provides in day time (not direct

sunlight) without glare into a building through the holes in external fabric such

as; windows, roof lights, etc from the right direction. For the design criteria

“Daylight factor” is very important and it is a measure of daylight at a point in

a room relative to the light coming from whole sky. Day light is important to

the health of occupants and there are typical recommended minimum daylight

factors for all types of buildings. Fenestration sought to be designed according

to the maximum benefit of daylight with the shape, position, size and glazing-


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-materials for window and roof openings in the building. The interior colour and

finishing, flooring material (gloss tiles) and positioning of mirrors can helpful to

increase the daylight factor by reflection as well.

Sunlight and passive solar gain

Sunlight is the direct rays appeared from the sun through the atmosphere to

inside the building through the windows and openings. The openings and the

layout of rooms should be designed in residential building, to be allowed

sunlight to enter to the living room, kitchen and bedrooms for at least one hour

per day for 10 months of the year. Direct sunlight in a building can cause

intensive glare, overheating and fading of surface colours. Shading and

reflective devices include trees, overhangs, louvers, blinds, shades and curtains

are helpful to reduce the glare. Using of double glazing units with reflecting

outer face can be minimizing the heat transmission through the window

opening.

Careful orientation of buildings is vital for passive solar gain. The permanent

shadows should be avoided by using their major axis of the buildings from

north-east to south-west, or south-east to north-west. The roads also try to

align with east-west direction and minimizing over shading by locating taller

buildings to the north side or to the south of road junctions. For layout of

buildings can reduce the over shade of open areas, always locate shorter

buildings to the south and taller buildings to the north as well. The internal

form of house shall be oriented the most frequently used rooms facing south

and least used rooms facing north. Especially living room has to be located in

south and bathroom and utility rooms shall be in north.

Sound

Sound is a form of energy can be created by series of pressure waves in air or

other medium. Air, water, wood or metal is common sound transmitting

mediums. The outside unwanted sound (noise) can be transmitted through the

external fabric of the building by Airborne, Impact and flanking sound

transmission. The controlling of noise inside and outside of the building is

necessary for better living condition of the people. From the external noise,

nuisance is most often caused by motor traffic. The type of external walls, floor

and types of glazing of door and windows has to be considered to reduce and

control the outside noise transmission to the building. Sound absorption

reduction of echo is necessary for better listening conditions in small houses.

The block and brick cavity walls double glazing units and separating of floors

are helpful to reduce noise. The location of the building and the layout should

be very important to reduce the external noise as well.


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APPENDICES.

APPENDIX A

FIGURE 2.1 – Some waterproofing principles of pitched roof.



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APPENDIX B

FIGURE 2.2- Damp proof membrane below ground floor slab.

Source: Mitchell's –Introduction to Buildings (4th Edition)


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APPENDIX C

FIGURE 2.3 – Thermal insulation to ground floor slab

Source: Mitchell's –Introduction to Buildings (4th Edition)


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REFERENCE:

CEM (2008) Building Technology 01, Finishes, paper 1387 page 13, Reading:

College of Estate Management.

Derric Osbourn and Roger Greeno (2007) Mitchell's' Building Series,

Introduction to Buildings (Fourth Edition)

Esmond Reid (2005) Understanding Buildings

Total number of pages: 14


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Asignment 01 F103TEC- 2011

Documents

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