3. What are roofs?
In one sentence,
• the structure forming the upper covering of a building.
4. 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.
5. History of Roof
• The earliest known roofing was the woolly skin of a giant
mammoth noted in Siberia during 40,000 BC.
19. Common Rafters
• Main load-bearing members of the roof.
• Spans between a wall plate at eaves & ridges.
20. 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.
23. Purlin
• Horizontal roof members which give intermediate support to rafters.
• Acts as beam, reducing the span of rafters & enabling economic
section to be used
27. 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.
28.
29. 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.
30. Flat Roof
Advantages
• 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.
31. 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
32. Shed Roof
Advantages
• Simple design
• Requires basic roofing materials
Disadvantages
• Develops drainage problems
• Cannot be retrofitted to other types of roof as its cost effective
33. • 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
36. • Trusses are designed based on a triangle principle.
King Post Truss Queen Post TrussMansard Truss
Truss Roof
37. 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.
38. 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.
39. Hip Roof
ADVANTAGES
• 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.
40. Gambrel Roof
• Gable roof design, two
slopping surfaces
• Also known as a barn roof.
• Provides extra space in
the attic.
• Difficult for ventilation
41.
42. Mansard Roof
• Hip roof design, double
slope on all sides
• A French design
• Allows for use of dormers
• Accumulates water
43.
44. Butterfly Roof
• An inverted gable
roof design
• Visually stunning
• Useful in climates
with severe winds
• Water drainage
problem
45.
46. 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
47.
48. 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
49.
50. 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.
51. Roof Shell
Advantages
• 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.
52. 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
54. Geodesic
Advantages
• 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.
55. Dome Roof
A dome is an architectural element that
resembles the hollow upper half of a sphere.
56. Dome Roof
Advantages
• Striking appearance
• Energy efficient
• Wind resistant
Disadvantages
• Quirky roof shape may affect resale appeal
• May be more expensive to construct
58. Tensile Structure
Advantages
• 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
59. Space Frame
A truss-like, lightweight rigid structure constructed from
interlocking struts in a geometric pattern.
60. Space Frame
Advantages
• 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.
61. 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.
63. Tile Covering
• Clay, Concrete (overlapping
technique).
• Pitches from 15° to 45°.
• Pitch of tiles are less than
pitch of the rafters.
64.
65. 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
66. 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.
67. Thatch Covering
• Thatch – made of plant
stalks in overlapping layer
• Wheat & Rye straw –
widely used in Europe
country
• Seagrass – longer life than
straw
68.
69. Shingles Covering
• Shingles – like the scales of a fish
• Red cedar – life expectancy (30 years), high cost
• Hardwood – durable
70.
71. Slate Covering
• Slate – naturally dense material.
• Every sheet should be nailed twice.
• Minimum pitch of 25°.
• Central is nailed to overcome vibrations (wind).
72.
73. Sheet Covering
• Sheet cover – zinc, aluminium, lead
• Cheaper alternative.
• Short life.
• No creep light & ductile.
• Standard size : 2500mm x
1000mm, thickness 0.80mm.
75. Asphalt Covering
Advantages
• 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
77. Advantages
• Long Lasting
• Can accommodate with other floors
Disadvantages
• Leakage problems
• Maintenance can be problematic
• No room for multiple design patterns
Concrete Covering
79. Advantages
• Excellent insulation
• Unique looks
• Stormproof
• Solid
Disadvantages
• Heavy load on the walls
• Hard to transport
• Hard to construct
Stone Slab Covering
80. 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.
81. Types of Green Roofs
Green Roofs
Rooftop
Garden Edge
Restraint
Rooftop
Garden
Anchor
Roof System
Components
82. • 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
83. • 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
84. • 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
85. • 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
86. • 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
87. Something extra..
• Ever wondered how do they lift an existing roof to make an extra floor?
Here’s how.
88. • These are called CribPost system, best described as a series of temporary
hydraulic post-shores that can be extended to nearly any reasonable height.
89. • 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.
