pg. 1

BACHELOR OF QUANTITY SURVEYING QSB 1514 CONSTRUCTION TECHNOLOGY

LEE PEI GIE 0315653

TEE SIN YI 0315689

KHOO XIN YEE 0316180

LEONG CHEE MUN 0316256

THAN LEK MEI 0315538

YONG SEEN YEE 0315883

Submission date : 17.11.2014

pg. 2

CONTENT TABLE

No. Content

Pages

1 Part 1

About PJ Trade Centre

3 - 8

2 Part 2

i) Types of Foundation ii) Types of Slab iii) Types of Roof

9

10 – 12 13 – 16 17 - 19

3 Part 3 Compare and Contrast

i) Foundation ii) Slab iii) Roof

20

21 – 24 25 – 27 28 – 30

4 References

31

pg. 3

Part 1

About PJ Trade Centre

pg. 4

PJ TRADE CENTRE

“ The idea behind PJ Trade Centre (PJTC) starts with the observation that office

development in Malaysia, and generally in the region, is often not based on the optimal

solution. The typical glass, steel and aluminium box is repeated over and over again, regardless of the local culture, climate, context and construction methods. There seems to be a need for all office developers to follow the same direction in order to gain credibility.

The glass boxes get more and more complex, more and more uneconomical. It seems very difficult to change and do something different. ”

With plenty of natural light and cross-ventilation, PJ Trade Centre is designed as comfortable and healthy workplaces. Energy-efficient and eco-friendly design features lead to lower maintenance costs, but more importantly, has the potential to boost

productivity - reduce absenteeism, improved staff morale, higher work quality.

Instead of focusing on the usual Western-style office designs, which proliferate across

Malaysian cities, the architect, Kevin Mark Low has came up with the idea based on local culture, climate and context. There is a feeling of being close to nature, with a lushly landscaped Plaza of 2.5 acres and 12 Sky Terraces with hanging vines and wall creepers.

Many office units have balconies of about 325 square feet and open-to-sky washrooms.

PJ Trade Centre reflects a 'boutique' property - there are only 1 to 4 units per floor with a

minimum size of 2,100 square feet. Each unit has its own pantry and washroom and higher than normal ceilings of 3.8 metres.

Prepared by Than Lek Mei

pg. 5

Appealing unfinished brick walls

The buildings here were built referring to western countries as the walls were not covered by cement. The entire PJ Trade Centre is mostly built by bricks. It makes the building

looks distinctive among the other buildings.

Prepared by Than Lek Mei

pg. 6

Attractive concrete appearance

The concrete elevation stairs in PJ Trade Centre.

The relaxing zone and waiting area for guests in PJ Trade Centre.

Prepared by Than Lek Mei

pg. 7

Lush green

These are the patio in PJ Trade Centre with surrounding covered by lush green.

Prepared by Than Lek Mei

pg. 8

Lembaga Hasil dalam Negeri located in PJ Trade Centre. One of the impressive things we found is the lift outside of Lembaga Hasil office

designed for the disabled people.

These are the separate block in PJ Trade Centre which are Bata and Gamuda

headquarters.

The buildings are built up with glass window. It makes the

building looks wider and brighter with natural light.

This building is also built up with glass flat roof which

provides natural light.

The concrete beams.

Others

Prepared by Than Lek Mei

pg. 9

Part 2

Analysis

pg. 10

FOUNDATION

DEFINITION

Foundation is the lowest load-bearing part of a building, typically below ground level. It is the most important part of the construction that provides support to the building and also transferring the loads of buildings to the below ground level.

PURPOSE OF FOUNDATION

The first purpose of a foundation is a building will always move when it is built. It can sink, rise, slide, or combine these motions. Therefore, foundations ensure that the load of

a building is spread evenly over the ground underneath the building. The second purpose of a foundation is to tie the different parts of the building together so that it does not sink

unevenly and crack. Finally, foundations anchor the building to prevent its moving sideways when, for example, it is built on sloping ground.

Prepared by Yong Seen Yee

pg. 11

TYPES OF FOUNDATION

Foundations are generally divided into two categories:-

Shallow foundation

Shallow foundation is a type of foundation which transfers building loads to

subsoil at a point near to the ground floor of a building. The example of shallow

foundations is strip foundation, trench foundation, raft foundation and pad

foundation.

Deep foundation

Deep foundation is a type of foundation which transfer load to subsoil some

distance below the ground floor of a building which is contrast to shallow

foundation. The example of deep foundation is piled foundation.

Different types of building have to use different types of foundation. It is depend

on various condition and applications such as ground condition, the presence of

water, the nature of the load requiring support, accessibility, sensitivity to noise

and vibration, proximity to other structures and project time frames.

ADVANTAGES OF FOUNDATION

1. Piles can be precast to the required specifications.

2. Piles of any size, length and shape can be made in advance and used at the site. As a result, the progress of the work will be rapid.

3. A pile driven into granular soil compacts the adjacent soil mass and as a result the bearing capacity of the pile is increased. 4. The work is neat and clean. The supervision of work at the site can be reduced to a

minimum. The storage space required is very much less. 5. Driven piles may conveniently be used in places where it is advisable not to drill holes

for fear of meeting ground water under pressure. 6. Driven pile are the most favoured for works over water such as piles in wharf structures or jetties.

CHARACTERISTIC OF PILE FOUNDATION

Pile foundations are considered as deep foundations. It is a group of piles that supports a superstructure. Pile cap will connect with the piles together and distributes the

superstructure loads to the layer beneath. They are formed by long, slender, columnar elements typically made from timber, steel, concrete, or a combination of these materials, usually forced into the ground to transfer the load to underlying soil or rock layers.

Prepared by Yong Seen Yee

pg. 12

Pile foundations are used to transfer the loads from a superstructure, through weak, compressible strata, more compact, less compressible and stiffer soil or rock at depth.

Normally, they are used for large and heavy structures, and in situations where the surface soils at a proposed site are too weak or compressible to provide enough support.

WAYS OF TRANSFERRING STRUCTURAL LOADS

These are several ways of transferring structural loads into the subsoil on sites where

ground conditions are unfavourable. The bearing capacity of the subsoil can be increased by ground improvement techniques such as end-bearing pile, friction pile and the combination of end bearing & friction pile.

• End bearing pile End bearing piles are piles that are driven vertically and used for the direct support of

vertical loads are called bearing piles. Bearing piles transfer the load through a soft soil to an underlying hard layer. They also distribute the load through relatively soft soils that are not capable of supporting concentrated loads.

• Friction pile Friction piles are the piles that driven into soil of fairly uniform consistency and the tip

are not seated in a hard layer, the load-carrying capacity of the pile is developed by skin friction. The load is transferred to the adjoining soil by friction between the pile and the surrounding soil. The load is transferred downward and laterally to the soil.

• A combination of end bearing and friction pile Most piles use some end-bearing and some friction, in order to resist the action of loads.

It is a fairly soft soil that provides frictional resistance and then into a form layer which develops a load carrying capacity.

ANALYSIS

In conclusion, we found that the foundation of PJ Trade Centre is pile foundation. There are a few reasons why the pile foundation is used as the foundation for this building (PJ Trade Centre). First of all, PJ Trade Centre is a multi-storey building which consists of

very high carrying heavy concreted loads. PJ Trade Centre comprises of a 21-storey tower, four 20-storey towers and a 2-storey annex building. The soil is very soft as solid

base is not available at a reasonable depth to keep the bearing power within safe limits. Besides, the condition of the soil is too weak and compressible. Therefore, it would be more suited for this building to use pile foundation in order to provide a strong and

durable base to support the load of the building.

Prepared by Yong Seen Yee

pg. 13

SLAB

DEFINITION

Slab is a flat piece of concrete, typically used as a walking surface, but may also serve as

a load bearing device as in slab homes.

FUNCTIONS OF SLAB

Provide a flat surface

Support load

Sound, heat and fire insulator

Act as a divider for the occupants

Upper slab acts as the ceiling for the storey below

Space between slab and ceiling can be used to place building facilities

Prepared by Lee Pei Gie

pg. 14

TYPES OF FLOOR SLAB

Concrete slabs come in various forms, which can be divided into two categories – precast or in situ, depending on where the concrete was cast. Wherever the concrete is casted it

may be reinforced or prestressed. Reinforced concrete uses steel bars to resist the tension in the slab. Prestressed concrete has high strength steel strand cast in it which compresses the concrete and maximizes the benefit of concrete compressive strengths.

1) PRECAST CONCRETE FLOORS

Reinforced concrete is widely used for the construction of suspended floors for all types of buildings. Floors composed of reinforced precast concrete units have been developed over the years to overcome some or all of the disadvantages of in-situ reinforced concrete

slab such as needs for formwork, time taken for the concrete to cure before the formwork can be released for reuse and the floor available as a working area, and very little is

contributed by a large proportion of the concrete to the strength of the floor.

Advantages of Precast Concrete Floors

Very rapid speed of erection

Good quality control

Entire building can be precast-walls, floors, beams, etc.

Rapid construction on site

High quality because of the controlled conditions in the factory

Pre-stressing is easily done which can reduce the size and number of the structural

members.

Disadvantages of Precast Concrete Floors

Very heavy members

Camber in beams and slabs

Very small margin for error

Connections may be difficult

Somewhat limited building design flexibility

Because panel size is limited, precast concrete

cannot be used for two-way structural systems.

Economics of scale demand regularly

shaped buildings.

Prepared by Lee Pei Gie

pg. 15

2) IN-SITU CONCRETE SLAB

In situ reinforced concrete slab options include :

Ribbed ( Waffle ) Slabs Flat Slabs

Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. This form of construction is not

very common because of the formwork costs and the low fire rating. Ribbed slabs

are suitable for medium to heavy loads, can span reasonable distances, are very stiff and particularly suitable where the soffit is

exposed.

Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of

beams. Flat slabs are highly versatile elements widely used in construction,

providing minimum depth, fast construction and allowing flexible column grids.

Advantages

Savings on weight and materials.

Stability - A waffle slab gives a substance

significantly more structural stability without using a lot of additional material.

This makes a waffle slab perfect for large flat areas like foundations or floors.

Attractive soffit appearance if exposed.

Economical when reusable formwork pans used.

Vertical penetrations between ribs are easy.

Advantages

Construction - Construction of flat slabs is one of the quickest methods available. Lead times are very short as this is one of

the most common forms of construction.

Cost, whole life cost, value - Flat slabs are particularly appropriate for areas where tops of partitions need to be sealed to the

slab soffit for acoustic or fire reasons. Flat slabs are considered to be faster and more

economic than other forms of construction, as partition heads do not need to be cut around downstand beams or ribs.

Flat slabs can be designed with a good

surface finish to the soffit, allowing exposed soffits to be used. This allows exploitation of the building’s thermal mass

in the design of heating, ventilation and cooling requirements, increasing energy

efficiency.

Disadvantages

Depth of slab between the ribs may control

the fire rating.

Requires special or proprietary formwork. Greater floor-to-floor height.

Disadvantages

Drop panels may interfere with larger

mechanical ducting

Vertical penetrations need to avoid area around columns

For reinforced flat slabs, deflection at the middle strip may be critical.

Prepared by Lee Pei Gie

pg. 16

ANALYSIS

During site visit at PJ Trade Centre, we found that the buildings are mostly made of the unfinished brick and concrete and it is interesting in the way it manages to meet the

ground without clutter. PJ Trade Centre comprises of a 21-storey tower, four 20-storey towers and a 2-storey annex building. Thus, there are ground floor slab and suspended slabs. Nonetheless we are only allowed to access the building to first floor, so our

analysis will be based on ground floor slab first and second floor slab.

Ground Floor Slab

According to our analysis, we suggest that the ground floor slab used in PJ Trade Centre is in-situ concrete slab. While the type of in-situ concrete slab used is flat slab. The slab

design is designed to be reinforced in several directions so that it can withstand stresses. Furthermore, it is flexible to the occupier who can easily alter internal layouts to

accommodate changes in the use of the structure. With the introduction of drop panels at column locations the form work becomes slightly more complex than that of a flat plate but it is still a relatively simple procedure and the drop panels add to the shear strength of

the slab.

Suspended Floor Slab As for suspended floor slab, we suggest that the in-situ concrete slab is used as well in first floor and second floor slab. What different from ground floor slab is that the type of

in-situ concrete slab used is ribbed ( waffle ) slab. Resembling the food after which they are named, the type of slab used is reinforced concrete floors and roofs that use a square

grid of deep sides. This form of construction is usually used in airports, parking garages, bridges, residences and other structures requiring extra stability. In addition, it is also used in commercial and industrial buildings like PJ Trade Centre.

Prepared by Lee Pei Gie

pg. 17

ROOF

DEFINITION OF ROOF

A roof protects the building and its content from the effect of weather.

IMPORTANCE OF ROOF

I. Durability A higher quality roof will long lasting than low quality roof. It will be more likely

to stand up under the routine wear and tear of sun, wind, rain and storms.

II. Protection

Roof’s primary job is protection. As a low quality roof, it doesn’t perform well on this job.

III. Efficiency

Roof serves as a vital heat and humidity release valve for ours house. Proper

insulation creates a transitory heat zone that can help ours home stay warm in night and rainy day.

Prepared by Leong Chee Mun

pg. 18

FUNCTION OF ROOF

I. Human Protection Roof is to provide protection to person inside a structure from the elements.

Without a roof, inhabitants inside a structure would be directly subjected to all these weather changes and suffer the physical ailments that result from this exposure.

II. Protection of Possessions

Possession such as furniture, carpet and appliances will be ruined quickly when rain water inside the structure.

FLAT ROOF

Flat roofs are an often lower cost and easier to install alternative to traditional pitched

roofs. A flat roof is a roof which is almost level in contrast to the many types of sloped roofs. The slope of a roof is properly known as its pitch and flat roofs have up to approximately 10°.

TYPES OF FLAT ROOF SYSTEM

1. Rubber Roof

It holds up against severe weather, temperature changes fire and leaks is an extremely durable surface. The costs of rubber roof is higher than an asphalt shingle product, however rubber roof offer a long lasting product that is very

durable and resistant to cracking, fading and crumbling.

2. Ethylene Propylene Diene Monomer (EPDM) This compound is highly UV resistant, waterproof, heat resistant and extremely adaptable to cold weather changes, ice and snow, therefore it is most effective

tool in flat roof today. EPDM can be used on any type of roof system, including roof top gardens, ponds, tunnels, terraces and on RV roofs making this the most

durable and adaptable roofing product found today.

3. Asphalt Build Up Roof (BUR)

Multiple layers of reinforcing layers and asphalt go into building. These roof uses tar and gravel, which are most common. This flat roof system becomes dry and

brittle in the sun and shows signs of cracks quickly. These tar and asphalt are very inefficient and required a great deal of energy to install. Therefore, the lifespan of BUR may only be eight to ten years.

Prepared by Leong Chee Mun

pg. 19

ADVANTAGES AND DISADVANTAGES OF FLAT ROOF SYSTEM

ANALYSIS

After visiting PJ Trade Centre, we found that PJ Trade Centre is using flat roof as their protection since flat roof is the best choice on very large size building. Installing a pitch roof on such a building is not recommended, because it will be a lot more difficult, costly

and will require special engineering to accommodate the additional structural weight. Besides, PJ Trade Centre is built as a green building therefore flat roof was chosen as

priority because it is energy efficiency which considered to be highly reflective up to 90% of heat back into the atmosphere.

Advantages Disadvantages

Allows for walk decks to be

incorporated

Very easy access

Easy installation of solar panels.

Less framing materials when

building a home

Very reflective and provides a

very energy efficient roof system in the warm climates.

Lifespan for a felt flat roof of

only 20 years

Drainage or lack thereof

Limited capacity for insulation

More expensive to repair

Prepared by Leong Chee Mun

pg. 20

Part 3

Compare and Contrast

pg. 21

FOUNDATION

In this part, we will be comparing the construction material that is foundation with two other different types of each of them.

1) RAFT FOUNDATION

A raft foundation consists of a raft of reinforced concrete under the whole of a building.

Raft foundations may be used for buildings on compressible ground such as very soft clay, alluvial deposits and compressible fill materials where str ip, pad or pile foundations

would not provide a stable foundation without excessive excavation. The reinforced concrete raft is designed to transmit the load of the building and distribute the load over the whole area under raft, reducing the load per unit area placed on the ground (Figure

3.21).

Distributing the loads in this way causes little, if any, appreciable settlement. The two types of raft foundation commonly used

are the flat raft and the wide toe raft.

The flat slab raft foundation may be used under small buildings such as bungalows and two storey houses where the

comparatively small loads on the foundations can be spread safely and

economically under the raft. The concrete raft is of uniform thickness and reinforced top and bottom against both upward and

downward bending.

Prepared by Khoo Xin Yee

pg. 22

When the reinforced concrete raft has dried and developed

sufficient strength walls are raised as illustrated in Figure

3.22. The concrete raft is usually at least 150mm thick.

In areas subject to mining subsidence the flat slab is cast

on a bed of fine granular material, 150mm thick, so that the raft is not keyed to the

ground and is therefore unaffected by horizontal

ground strains. Where the ground has poor compressibility and the loads on the foundations would require a thick, uneconomic flat slab, it is usual to cast the raft as a wide toe raft foundation. The raft is cast with a reinforced concrete stiffening edge beam,

from which a reinforced concrete toe extends as a base for the external leaf of a cavity wall, as shown in Figure 3.23 and 3.24.

PAD FOUNDATION

Pad foundations can be used to carry point loads, They can also be designed so that the loads of the walls and the buildings are transferred through ground beams that rest on the

pad foundations. Pad foundations transfer the loads to a lower level where soil of sufficient load bearing strata exists (Figure 3.19). The width of a pad foundation can be

increased to distribute the loads over a greater area, thus reducing the pressure on the ground.

Prepared by Khoo Xin Yee

pg. 23

CONTRAST BETWEEN PILE FOUNDATION, PAD FOUNDATION AND RAFT

FOUNDATION

Pile Foundation Pad Foundation Raft Foundation

Costing

The most expensive and the strongest

type of foundation.

The least expensive among the other two (Pile foundation and

Raft foundation)

It is more expensive than pad foundation but cheaper than pile

foundation

Strength/Quality Strongest type of

foundation

Pad foundation is not as strong as pile

foundation, considered the weakest among the

other two (Pile foundation and Pad

foundation)

Stronger than Pad foundation but not as

strong as Pile foundation

Machinery

Requires big

machineries such as bigger cranes to build

something big

(skyscrapers, etc.)

This type is easier to

construct and don’t need some machineries that

are required for pile

foundation.

This type is easier to

construct and don’t need some machineries that are required for pile

foundation.

Labour

Requires specialist engineering to do

Pile foundation

Skilled workers not

really needed, depending on the

building

Needs skilled workers

sometimes, but not as skilled as to do Pile

foundation depending on

the building

Sustainability/

Resistance

Better

resistance/bearing capacity compare to

the other types

Considered having lower resistance

compared to Raft foundation and Pile

foundation

Raft foundation

resistance is higher compare to other types except pile foundation

Time Requires more time

to build

The quickest to be done compared to the other

two (Pile and Pad

Foundation)

Faster to be done than Pile foundation but not as

quick as Pad foundation

Prepared by Khoo Xin Yee

pg. 24

RECOMMENDATION

In our opinion, PJ Trade as a high-rise building is usually founded on some form of piled foundation which is subjected to a combination of vertical, lateral and overturning forces.

Combined pile-raft foundations can be a particularly effective form of foundation system for PJ Trade building because the raft is able to provide a reasonable measure of both stiffness and load resistance.

For the detailed information about the piled raft foundation, it utilizes piled support for

control of settlements with piles providing most of the stiffness at serviceability loads, and the raft element providing additional capacity at ultimate loading. Consequently, it is generally possible to reduce the required number of piles when the raft provides this

additional capacity. In addition, the raft can provide redundancy to the piles, for example, if there are one or more defective or weaker piles, or if some of the piles encounter

caustic conditions in the subsoil. Under such circumstances, the presence of the raft allows some measure of re-distribution of the load from the affected piles to those that are not affected, and thus reduces the potential influence of pile “weakness” on the

foundation performance.

Another feature of piled rafts, and one that is rarely if ever a llowed for, is that the pressure applied from the raft on to the soil can increase the lateral stress between the

underlying piles and the soil, and thus can increase the ultimate load capacity of a pile as compared to free-standing piles.

The most effective application of piled rafts occurs when the raft can provide adequate load capacity, but the settlement or differential settlements of the raft alone exceed the

allowable values.

The actions or loads acting on a high-rise building which is PJ Trade is higher. The loads include the composite column, reinforced concrete (RCC) walls, superimposed dead

loads consist of loads of permanent fixtures and fittings such as ceilings, air-conditioning ducts, floor finishes, partitions. All these tremendous loads need a stronger foundation

that can support more loads. Therefore, piled raft foundation is a good choice as the raft can help to transfer the load to the ground and it is supported by the piles. Furthermore, the presence of raft in piled raft foundation can provide redundancy to the piles. In

Damansara Perdana, it will rains heavily or rains continuously, hence the water is drained into the foundation and cause the erosion of piles. However, the raft can allows some

measure of re-distributions of the load from the weaker piles to the healthy piles. In short, the raft helps to reduce the influence of the weaker piles in the foundations. It makes the whole foundation become more durable and safer. Overall, piled raft foundation is an

alternative to replace pile foundation of the PJ Trade Building.

Prepared by Khoo Xin Yee

pg. 25

SLABS

For this part, we will be comparing and discussing about two other types of

slabs instead of flat slab and ribbed slab.

PRECAST CONCRETE SLAB

After all, the concrete does not know it is precast, whether statically reinforced

or pretensioned which also known as prestressed. It is only when we consider

the role that this concrete will play in developing structural characteristics that

its precast background becomes significant. The most obvious definition for precast is that it is concrete which has been prepared for casting, cast and cured

in a location which is not is final destination.

Precast concrete slab does

not require any formwork.

Besides, time taken for concrete to cure in the

formwork can be

eliminated. It has better

quality control compare to others. Moreover, precast

concrete slab does not need

many workers as in in-situ concrete construction and

it is a fast completion of

construction project.

There are many types of precast concrete floor such as:

a) Precast hollow floors

b) Composite floors

Precast hollow floor units are available in a

variety of sections such as box planks/

beams, tee section, I beam sections and

channel sections. Composite floors are combination of precast units and in-situ

concrete.

Prepared by Tee Sin Yi

pg. 26

Precast hollow slab

Precast hollow slab is more economic compared to in-situ floor die to reduction

in volume of concrete used, weight of reinforcement and size of foundation. It

is cheaper than composite. It goes without saying that in-situ concrete is not required. On top of that, units are self centering so, no need temporary support.

Moreover, construction period is also shorter when using precast hollow slab

compare to others.

Composite Floors

Composite floor is the combination of precast units and in situ concrete. Precast

units that are usually prestressed/ reinforced with high yield bars are used to

provide the strength of the floor with the smallest depth practicable. At the

same time, it acts as permanent formwork to the in-situ topping that provides the compressive strength required.

TIMBER FLOORING

Timber flooring has proven itself a timeless product, offering a warmth and natural beauty largely unmatched by other flooring products. This guide

provides on overview to the installation method of solid timber strip flooring

over bearers and joists, timber based sheet flooring products and concrete slabs. Timber flooring is typically supplied as either solid timber or laminated wood

products, made from layers of bonded timber. It fits together with a tongue and

groove joint and once in place, is sanded and finished. There is a wide variety

of species to select flooring from and the right species for a given application will be dependent on numerous factors. Information relating to species

selection, environmental assessment, finish selection and recommended

maintenance routines are all provided within this guide.

Prepared by Tee Sin Yi

pg. 27

CONTRAST BETWEEN PRECAST CONCRETE, REINFORCED IN-

SITU CONCRETE AND TIMBER FLOORING

Precast concrete Reinforced in-situ concrete

Timber flooring

Elimination of the need

for formwork

Formwork needed No formwork is

required. Easy to construct and adjust on

site.

Less flexible in design

term

Embrace various shape Higher aesthetical value

compared to concrete

floor

Superior quality control

of product is possible with factory produced

components

Better working

condition for the building operatives

Easy on the home

owners’ feet and legs (concrete slabs are hard

on legs and cold

underfoot)

Curing time of concrete

is eliminated therefore

the floor is available for use as a working

platform at an earlier

stage

Construction can

proceed independently

of weather condition. It is not necessary ti pay

for crane on site.

Allows the most

efficient placement of

heating systems. Perfect choice when building in

potentially low lying

flood prone areas.

RECOMMENDATION

The alternative for replacing reinforced cast in-situ floor slab would be precast

concrete floor slab. It has a high durability while precast concrete is

exceptionally resistant to impact, corrosion, weathering, abrasion and other

ravages of time, reducing maintenance and operation costs. A low water-cement ratio combined with good compaction and curing in a controlled factory

environment ensures a dense, highly durable concrete. Precast concrete is also

non-combustible with inherent fire-resistant capability, creating a safe envelope that helps protect personnel, equipment and the building itself. This in turn may

be able to reduce insurance rates.

Prepared by Tee Sin Yi

pg. 28

ROOF

In this part, we will be comparing the construction material that is roof with two other different types of each of them.

GABLE ROOF

Gable roof end is a pitched roof sloping on two sides.

The ridge board which is considered as the spine of the roof runs along the center and the peak of the roof. The

common rafters are nailed to the ridge board and slope downwards to the external walls resting on the wall plate in a birdsmouth joint. The battens are placed

horizontally on the rafters on the opposite direction to receive the appropriate covering.

Figure 13.0 shows cross section of typical gable

roof.

It is especially used in areas where the climatic conditions are rainy and

contains high prevailing winds. Gable roof contains more brickwork to provide

the gable end. The gable end or gable face can be made up of brickwork or timber cladding. The extra brickwork

provides faces to the building. Gable roof is preferred over other types of roof

because the two inclination meeting at the ridge board hence less woodworking.

The degree of slope provides additional spacing underneath where it is used for water storage cistern, and services.

Brunei is a country whereby its climatic conditions are humid, hot and containing heavy downpour throughout the year. This principle and this roof construction method can be

proved ideal for another roof alternative to be considered for our case of study for Pitched roof is based on the principle of cold air-sink and hot air rises especially gable end attic

roof. Furthermore it is easier to maintain and is less likely to leak. Unlike a flat roof, the

replacement of tile covering or timber will be easy for they are made of singular individual units.

Prepared by Tee Sin Yi

Prepared by Tee Sin Yi & KhooXin Yee

pg. 29

HIP ROOF

Hip roof, also called

hipped roof, roof that slopes upward from all sides of a structure,

connecting the walls of the building, having no

vertical ends. Trusses are found in the interior of the roof, designed

with short ridge boards, having several types of

rafters: hip rafters, jack rafters & common rafters. There are many

different variations on the basic “ hip roof "

design, created mostly to suit different styles of house.

Hip Roof

Hip and Valley

The hips and valleys on a hip and valley roof describe the points where the different parts of the roof meet.

Broken Hip and Valley Almost the same as a hip and valley roof, except that the roof

is not level - some ridges and points are higher than others.

Belcote Has a verandah attached that runs all the way around its perimeter.

Prepared by Tee Sin Yi & KhooXin Yee

pg. 30

CONTRAST BETWEEN HIP ROOF, GABLE ROOF AND FLAT ROOF

RECOMMENDATION

I would recommend steep slope roofing. The justification is that slope roofing is more

suitable for high rise building. Generally, roofing types and roofing products are typically divided up into two primary categories, steep slope roofing and low slope roofing. Sometimes steep slope roofing is

also referred to as “residential roofing” due to the fact that most single family homes in the U.S. are constructed with some sort of pitch or slope to the roof. Just as steep slope

roofing is often referred to as residential roofing, the term low slope roofing is oftentimes synonymous with “commercial roofing”. Again, this is due to the fact that, predominantly, commercial buildings have “flat” roof designs.

As a matter of fact, Petaling Jaya Trade Centre is a combination of residential building and commercial building. Thus, low slope roofing or steep slope roofing are good choices

for that. Roof slope is a very important aspect and it is considered the primary factor in roof design. The slope of a roof has an effect on the interior volume of a building, the drainage,

the style, and the material used for covering. For example, if you notice water collecting on the roof the problem is probably related to the slope. The style is affected too because

the framing of the roof changes the slope.

Hip & Valley Roof Gable & Valley Roof Flat Roof Installation Involves more

construction & knowledge Simpler & more economical to build

Uses rubber rolls & quicker to install

Space Trusses structures under the roof, can contain chimneys

Extra space for attic or extra room & access for maintenance

Can place beneficial objects that settle on flat surfaces

Cost Complex structure & more construction time causes costly price

Reduced price due to popularity & easy construction

Costly at first, but beneficial in the long run

Durability Design causes wind protection & strength, arguably the best among roofs

Very unsuited to windy areas due to design, which can peel off the roof

Rubber layer makes it durable for extreme weather, scruffs, tears & leakage

Suitability (To environment of original house)

Decent rain runoff ability, longer eaves for shading.

Steep slope makes it the best among roofs for water runoff

Heat absorption & insulation, suitable for Malaysia’s dry & wet seasons

Appearance Roof connects with walls & has 4 slopes, allowing use of gutters

Fully exposing 2 sides allowing extra room hence allows extra windows

Horizontal base & appealing looks when patio & gardens are placed

Prepared by Tee Sin Yi & Khoo Xin Yee

pg. 31

REFERENCES

http://www.roofportland.com/flat-roofing-portland-oregon/ http://www.morganasphalte.co.uk/news/advantages-disadvantages-pitched-flat-roofing/

http://conestogaroofing.com/FlatRoofSystems.html http://v5.books.elsevier.com/bookscat/samples/9780750650847/9780750650847.PDF http://www.ce.memphis.edu/6136/PDF_notes/F_slabs.pdf

http://enginemechanics.tpub.com/14081/css/14081_349.htm http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm

http://www.abuildersengineer.com/2012/11/driven-piles-advantages-and.html http://www.tujuangemilang.com/pdf/wallstreet.pdf http://www.pjtradecentre.com/about.html

Chudley, R. (1974), Construction Technology: Floors and roofs. Published by

Longman Singapore Publishers ( Pte ) Ltd.