RooFAndrew Mah

Aishath Hussain

Chee Wei Shan

Chen Shin Yee

Chong Hui Xin

Chong Kai Xian

Chuang Jing

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 temperatures.

• 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.

History of Roof

• The first known glazed clay roof tile was used in China 5,000 years ago.

• Greece and Babylon used flat earthenware roof tiles between 4,000 and 5,000 years ago.

• The Romans brought variations of the Greek clay tiles to England as early as 100 BC.

• Around 735 AD thatched roofs were developed and used. Wood shingles were introduced 300 years later.

• Industrial production of clay roofing tiles began in the 19th century. One hundred years later concrete roof tiles were first used.

Components of a Typical Roof

Ridge • The horizontal top area where two sloped roof areas meet.

• Spine of a roof

Hipped End• The roof slope is continued around the end of a building of a

hipped end roof.

Rafters• Splay cut / bevelled & nailed to ridge board at upper ends

& birth-mouthed nailed to wall plate at lower ends

Hip Rafters• Frame the external angles of hipped end roofs.

Jack Rafters• The shortened rafters running from hip rafters to plate

& from ridge to valley rafters.

Valley Rafters• Used at internal angles of roofs.

Common Rafters• Main load-bearing members of the roof.

• Spans between a wall plate at eaves & ridges.

Wall Plate / Plate• Provide the bearing & fixing

medium for various roof members.

• Distribute the loads evenly over the supporting walls.

• Bedded in cement mortar on top of load-bearing walls.

Eaves• Bottom portion of the roof overhanging the wall.

Verge• Roof covering that overhangs at the gable end.

Purlin• Horizontal roof members which give intermediate support to rafters.

• Acts as beam, reducing the span of rafters & enabling economic section to be used

Overall Rafters

Oh, flat roofs do exist too!But we don’t learn about it.

Types of Roof

Flat Roof• 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.

Flat Roof• 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.

Flat RoofAdvantages

• No space lost below roof.

• Pleasing appearance.

• Easier to build and less material used.

Disadvantages

• 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 other styles.

Shed Roof

Shed RoofAdvantages

• Simple design

• Requires basic roofing materials

Disadvantages

• 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 rises vertically.

• 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.

Pitch Roof

Pitch Roof Members

• Trusses are designed based on a triangle principle.

King Post Truss Queen Post TrussMansard Truss

Truss Roof

Cut Roof• Consists of rafters and joists. The joists prevent the outward

spread of the rafters/walls, and conveniently give support for the ceiling below.

Hip Roof• 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.

Hip RoofADVANTAGES

• Well suited to warm climates.

• Hip roofs have eaves all around which protects the walls from sun and adverse weather.

• Water drainage capability.

DISADVANTAGES

• Design is more complicated (complex system of trusses and rafters)

• Due to the angles they have less attic space.

Gambrel Roof

• Gable roof design, two slopping surfaces

• Also known as a barn roof.

• Provides extra space in the attic.

• Difficult for ventilation

Mansard Roof

• Hip roof design, double slope on all sides

• A French design

• Allows for use of dormers

• Accumulates water

Butterfly Roof

• An inverted gable roof design

• Visually stunning

• Useful in climates with severe winds

• Water drainage problem

Dutch Hip Roof

• A hip roof with small gable ends at the ridge

• Sometimes used as architectural element

• Can be used for attic ventilation

• Costly

Winged Gable Roof

• Extended, variation for winged gable roof over a gable roof

• Give aesthetic look

• Advantages when a lot of snow or rain

• Problematic in high wind and hurricane areas

Roof Shell• A common type of roof that is made from thin material.

• The roof is curved and used to cover large, one-story buildings.

Roof ShellAdvantages

• More area is covered without any intermediate columns.

• There is no leakage problem in this type of roof.

Disadvantages

• 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

GeodesicGeodesic roof construction consist of a triangular frame placed together to form a dome.

GeodesicAdvantages

• Easy to build.

• Uses less material and are as structurally strong as traditionally built homes.

Disadvantages

• Doors and windows must be specially made and may be expensive.

• The spherical design creates a lack of usable space.

Dome RoofA dome is an architectural element that resembles the hollow upper half of a sphere.

Dome RoofAdvantages

• Striking appearance

• Energy efficient

• Wind resistant

Disadvantages

• Quirky roof shape may affect resale appeal

• May be more expensive to construct

Tensile StructureA construction of elements carrying only tension and no compression or bending.

Tensile StructureAdvantages

• Unique designs

• Lightweight and flexible

• Environmentally sensitive

• High strength weight ratio

Disadvantages

• Little to no rigidity

• Loss of tension is dangerous for stability

• Thermal values limits usage

Space FrameA truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern.

Space FrameAdvantages

• provides complete freedom in large span areas while providing strong resistance

Disadvantages

• The number and complexity of joints can lead to longer erection times on site.

Membrane roofing• A type of roofing system for buildings and tanks.

• It is used on flat roofs to prevent leaks and move water off the roof.

Advantage

• protects the roof from the

harmful effects of UV sunlight.

Types of Roof Covering

Tile Covering• Clay, Concrete (overlapping

technique).

• Pitches from 15° to 45°.

• Pitch of tiles are less than pitch of the rafters.

Plain Tiling• 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 corner

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 Covering

• Thatch – made of plant

stalks in overlapping layer

• Wheat & Rye straw –

widely used in Europe

country

• Seagrass – longer life than

straw

Shingles Covering• Shingles – like the scales of a fish

• Red cedar – life expectancy (30 years), high cost

• Hardwood – durable

Slate Covering• Slate – naturally dense material.

• Every sheet should be nailed twice.

• Minimum pitch of 25°.

• Central is nailed to overcome vibrations (wind).

Sheet Covering• Sheet cover – zinc, aluminium, lead

• Cheaper alternative.

• Short life.

• No creep light & ductile.

• Standard size : 2500mm x 1000mm, thickness 0.80mm.

Asphalt Covering

Asphalt CoveringAdvantages

• Affordable

• Variety of styles

• Easy installation

Disadvantages

• Not an environmentally friendly roofing material

• Gets damaged if installed at below freezing temperatures.

• Not resistant to extreme temperature variations

Concrete Covering

Advantages

• Long Lasting

• Can accommodate with other floors

Disadvantages

• Leakage problems

• Maintenance can be problematic

• No room for multiple design patterns

Concrete Covering

Stone Slab Covering

Advantages

• Excellent insulation

• Unique looks

• Stormproof

• Solid

Disadvantages

• Heavy load on the walls

• Hard to transport

• Hard to construct

Stone Slab Covering

Green Roofs• A vegetative layer grown on

the rooftop.

• Provide shade and remove heat from the air.

• Can be installed on a wide range of buildings.

Types of Green Roofs

Green Roofs

Rooftop Garden Edge

Restraint

Rooftop Garden Anchor

Roof System Components

• Reused Styrofoam insulation that was on roof.

• Water Barrier is the most important part of the roof, and is installed the same way as a standard roof.

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 waterproof layer.

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 capacity.

5. Water Retention 6. Soil Placement

• Spreads soil to consist depth – 3 inches deep.

• 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

Something extra..

• Ever wondered how do they lift an existing roof to make an extra floor? Here’s how.

• 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.

完成。 End.