1. Niraj Patel 9428891414 niraj.patel@darshan.ac.in
ROOF & ROOF COVERING
Niraj Patel
Building Construction ( ) Darshan Institute of Engineering & Technology

2. TOPICS TO BE COVERED Definition Technical terms Requirements
Classification
Types
Types of roof covering

3. What is it ?

4. What is it ?
It may be defined as uppermost part of building provided as a structural covering to protect the building from weather.
Structural elements may consist of trusses, portals, flat slabs, domes, beams, etc.
Roof covering material may be A.C. sheets, G.I. sheets, thatch, wooden shingles, tiles, slats or slab itself.

5. Trusses

6. Portal

7. Shells

8. Domes

9. Requirements of Roof
It should be structurally sound and strong enough to carry anticipated loads.
It should be durable.
It should be fire resistant.
It should have heat and sound insulation.
It should have efficient water proofing and drainage provisions.

10. Roof Components

11. Technical terms
Span : it is clear distance between supports of arch, beam or roof truss.
Rise of Roof : it is vertical distance between wall plate and top ridge.
Pitch of Roof : it is inclination of side of roof with horizontal. Expressed in terms of degrees or as ratio of rise to span.
Ridge : it is apex of angle formed by termination of sloping surfaces at top of slope.
Eaves : it is lower edge of sloping surface of pitched roof.
Valley : it is acute angle formed by intersection of two slopes in pitched roof.

13. Contd.
Hip : it is ridge formed by intersection of two sloping surface having exterior angle greater than 180°.
Hipped end : it is sloped triangular surface formed at the end of roof.
Gable : it is triangular portion of end wall of a sloped roof.
Verge : the edge of sloping roof at gable end, running between the eaves and ridge is known as a verge.
Common Rafters : these are sloping wooden members laid from ridge to eaves.
Purlins : these are wooden members used to support common rafter when span is large.

14. Types of Roofs Roofs may be divided into three categories:
Pitched roof
Flat roof
Curved roof

15. Pitched roofs
These are having top surfaces provided with slope for covering building.
Suitable for coastal regions and areas of heavy rainfall.
Slope of roof may vary from 1:1 to 1:3.
For heavy rainfall steeper slope are preferred while in hot and arid climatic regions mild slopes are preferred.
Material used are A.C. sheets, G.I. sheets, etc.

16. Benefits of Pitched Roofs
Cheapest.
Useful for building with limited width and simple shape.
Suitable for hilly regions.
Self weight is low as compared to other types of roofs.

17. Types of Roofs Lean to roof(single roof)
King post roof(triple member roof)
Queen post roof (triple member roof)
Steel roof truss (triple member roof)

18. Lean to Roof Simplest type of roof.
Provided for sheds, out houses, verandah, etc.
Maximum suitable span allowed is 2.4 m.

19. Contd.

20. King post roof truss Used for span varying from 5m to 9m.
It consists of
Tie beam
Two struts
Two principal rafter
A king post

21. Contd.

22. Queen post roof truss Used for span in range of 9 to 14m.
It differs from king post in having two vertical post rather than one.
It consists of
A straining sill
Two inclined struts
Two principal rafter
Two queen post
A straining beam

23. Queen post roof truss

24. Steel roof truss

25. Roof covering Thatched roof Wooden shingles Tiled roof AC sheets
GI sheets

26. Thatched Roof

27. Wooden shingles

28. Tiled roof

29. Asbestos Cement Sheet

30. Galvanized Iron Sheet

31. Flat Roofs
A roof laid at angle of less than 10˚ to horizontal is known as flat roof.
This may be made from RCC, precast concrete with flag stones supported on RSJ. In many case mud terrace roof are also constructed.
Efficient water proofing and roof drainage is an important requirement of flat roof.

32. Types of flat terraced roofing
Commonly adopted forms are :
Mud terrace roofing
Madras terrace roofing
Mud phuska with tile paving
Lime concrete terracing : Jodhpur type
Lime concrete terracing with tile paving
Bengal terrace roofing

33. Mud terrace Roof

34. Madras terrace roof

35. Mud phuska terracing with tile paving

36. Lime concrete terracing