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Chee Wei Shan
Chen Shin Yee
Chong Hui Xin
Chong Kai Xian
What are roofs?
In one sentence,
• the structure forming the upper covering of a building.
Roofs are important because…
• It provides protection from weather.
• It helps in reducing the heat loss from a building.
• It helps to keep the interior building cool.
• They are designed to accommodate stresses.
• They are designed to withstand movements from
• It provides lateral restraint & stability to walls around.
• It resists penetration & spreading of fire.
History of Roof
• The earliest known roofing was the woolly skin of a giant
mammoth noted in Siberia during 40,000 BC.
• A flat roof is a roof which is almost level in
contrast to the many types of sloped roofs.
• Low pitched roof 10 degrees or less.
• Suitable for spans up to 4000mm
• Flat roofs are an ancient type of roof,
mostly used in arid climates.
• It is the cheapest to build but the
maintenance cost is high.
• Concrete, timber and steel are the common materials used for flat roofs.
• Flat roof relies on some kind of membrane to keep the moisture out.
• No space lost below roof.
• Pleasing appearance.
• Easier to build and less material used.
• Drainage is not automatic.
• Limited capacity for insulation.
• No space to accommodate services.
A shed roof is basically a flat roof with a
greater angle allowing for greater runoff.
• Has a single slope.
• Easy to build and inexpensive.
• Frequently used for additions or with
• Simple design
• Requires basic roofing materials
• Develops drainage problems
• Cannot be retrofitted to other types of roof as its cost effective
• Is a roof structure where the roof leans to one
side of the house.
• Also known as lean-to roof.
• Pitch is calculated by the number of inches it
• There are two basic methods of pitched roof
construction which are truss roof and cut roof.
• Rafters are connected into the wall or supported
on a wall plate.
• These type of roofs have no joist at all.
• Trusses are designed based on a triangle principle.
King Post Truss Queen Post TrussMansard Truss
• Consists of rafters and joists. The joists prevent the outward
spread of the rafters/walls, and conveniently give support for
the ceiling below.
• Is a gable roof with angled ends where all
sides slope downwards to the walls.
• It is a popular choice but is more difficult to
build than a gable roof.
• These type of roofs can handle strong wings.
• Suitable for hurricane-prone areas.
• Commonly used in bungalows and cottages.
• Well suited to warm climates.
• Hip roofs have eaves all around which protects the walls from sun and
• Water drainage capability.
• Design is more complicated (complex system of trusses and rafters)
• Due to the angles they have less attic space.
• Gable roof design, two
• Also known as a barn roof.
• Provides extra space in
• Difficult for ventilation
• Hip roof design, double
slope on all sides
• A French design
• Allows for use of dormers
• Accumulates water
• An inverted gable
• Visually stunning
• Useful in climates
with severe winds
• Water drainage
Dutch Hip Roof
• A hip roof with small gable ends at the ridge
• Sometimes used as architectural element
• Can be used for attic ventilation
Winged Gable Roof
• Extended, variation for
winged gable roof over a
• Give aesthetic look
• Advantages when a lot of
snow or rain
• Problematic in high wind
and hurricane areas
• A common type of roof that is made from thin material.
• The roof is curved and used to cover large, one-story buildings.
• More area is covered without any intermediate
• There is no leakage problem in this type of roof.
• It can not be used to construct the upper floor.
• It has problems of natural light and ventilation.
Folded Plate Roof
• A roof which has been moulded to a shape.
• Meant for large covering of an open space.
• A roof constructed of flat plates, joined at various angles
Geodesic roof construction consist of a triangular
frame placed together to form a dome.
• Easy to build.
• Uses less material and are as structurally strong as
traditionally built homes.
• Doors and windows must be specially made and may
• The spherical design creates a lack of usable space.
A dome is an architectural element that
resembles the hollow upper half of a sphere.
• Striking appearance
• Energy efficient
• Wind resistant
• Quirky roof shape may affect resale appeal
• May be more expensive to construct
A construction of elements
carrying only tension and no
compression or bending.
• Unique designs
• Lightweight and flexible
• Environmentally sensitive
• High strength weight ratio
• Little to no rigidity
• Loss of tension is dangerous for stability
• Thermal values limits usage
A truss-like, lightweight rigid structure constructed from
interlocking struts in a geometric pattern.
• provides complete freedom in large span areas while
providing strong resistance
• The number and complexity of joints can lead to longer
erection times on site.
• A type of roofing system for buildings and tanks.
• It is used on flat roofs to prevent leaks and move water off the roof.
• protects the roof from the
harmful effects of UV sunlight.
• Clay, Concrete (overlapping
• Pitches from 15° to 45°.
• Pitch of tiles are less than
pitch of the rafters.
• Double lapping principle
• Wind is able penetrate into the building through gaps
• Rule : at least 2 thicknesses of the tile covering any
part of the roof and bond
Advantage :- Durable, lower cost (concrete)
Disadvantage :- Extra weight
Single Lap Tiling
• Overlapping side joint to minimum pitch of 35°
• Pantile – overcome the problem of 4 thickness at the
Advantage :- Lighter, permits a flatter slope of roof as they
are large in size & the actual inclination of the
tiles are greater.
Disadvantage :- Difficult to replace.
• Thatch – made of plant
stalks in overlapping layer
• Wheat & Rye straw –
widely used in Europe
• Seagrass – longer life than
• Shingles – like the scales of a fish
• Red cedar – life expectancy (30 years), high cost
• Hardwood – durable
• Slate – naturally dense material.
• Every sheet should be nailed twice.
• Minimum pitch of 25°.
• Central is nailed to overcome vibrations (wind).
• Sheet cover – zinc, aluminium, lead
• Cheaper alternative.
• Short life.
• No creep light & ductile.
• Standard size : 2500mm x
1000mm, thickness 0.80mm.
• Variety of styles
• Easy installation
• Not an environmentally friendly roofing material
• Gets damaged if installed at below freezing
• Not resistant to extreme temperature variations
• Excellent insulation
• Unique looks
• Heavy load on the walls
• Hard to transport
• Hard to construct
Stone Slab Covering
• A vegetative layer grown on
• Provide shade and remove
heat from the air.
• Can be installed on a wide
range of buildings.
Types of Green Roofs
• Reused Styrofoam insulation that was on
• Water Barrier is the most important part of
the roof, and is installed the same way as a
1. Roof Insulation Layer 2. Water Barrier
• After waterproofing store 2 inches of water
on the roof for 48 hours to test barrier.
• Root barrier is a thick plastic, which
prevents roots from penetrating the
3. Waterproof Testing 4. Root Barrier
• Water retention layer stores water in small
“cups” for use by plants after rain event.
• Installs filter fabric beneath soil, so not to
clog water retention layer. Specially
engineered, highly inorganic soil (very little
humus) with high water absorption
5. Water Retention 6. Soil Placement
• Spreads soil to consist depth – 3 inches
• Cover soil with photo-degradable wind
barrier to prevent wind erosion.
7. Soil Layer 8. Wind Barrier
• Plant through the wind barrier
with sedums, low-lying, hardy,
water-retaining plants that
thrive in harsh environments.
• Select several varieties based
on blooming, colour, etc.
9. Planting The Roof
• Ever wondered how do they lift an existing roof to make an extra floor?
• These are called CribPost system, best described as a series of temporary
hydraulic post-shores that can be extended to nearly any reasonable height.
• Each post is built up with bolted sections. The bottom of the post is
contained within a frame that holds a 25-ton capacity hydraulic jack which
pushes the post upward and allows new sections to be added at the bottom
as lifting progresses.