1. Roofing

2. ROOFS
It is constructed to protect the building from weather (rain, wind, heat, snow, etc)
Roof is the uppermost part of the building

3. REQUIREMENTS OF A ROOF Durable against various natural agencies
Adequate thermal insulation
Water proof
Fire resistant
Sound insulation
Good drainage arrangement

4. CLASSIFICATION OF ROOFS
Pitched or sloping
Single roof,
Double roof,
Trussed roof.
Flat or terraced
R.C.C roof,
Madras terrace roof.
Curved
Shell roof,
Dome roof.

5. PITCHED ROOFS
These roofs have sloping top surface
Suitable in those areas where rainfall/snowfall is very heavy
Span: clear distance between the supports of beams, roofs or truss
Rise: vertical distance between the top of the ridge and the wall plate
Pitch: inclination of sides of a roof to the horizontal
Ridge: an apex line of a sloping roof

6. PITCHED ROOFS

7. TERMS - ROOF
Gable: triangular upper part of a wall formed at the end of a pitched roof
Purlin: horizontal member placed over the principal rafters to support the roof membrane.

8. TERMS - ROOF

9. TYPES OF PITCHED ROOFS Single roofs Double or purlin roofs
Trussed roof
King post truss
Queen post truss
Mansard truss
Bel fast truss
Steel truss
Composite truss

10. SINGLE ROOF: 1.LEAN TO-ROOFS
Rafters slope to one side only.
Upper ends- rafters are fixed by nails to the wooden plates.
Lower ends- rafters are notched & nailed to the wooden post plate.
Battens are placed and fixed over rafters.
Roof covering materials.
Spans upto 2.5 m.

11. 2.COUPLE ROOF Pair of rafters Slopes to both sides
Upper ends- nailed to common ridge piece
Lower ends- notched & nailed to wooden wall plates.
Battens are fixed
Roof covering materials
Span upto 3.60 m.

12. 3.COUPLE CLOSE ROOF
Tie beam
Prevent from spreading
Spans upto 4.20 m.

13. COLLAR BEAM ROOF Span increase or heavy load- leads to bend
Prevent by raising the tie beam
1/3rd to ½ of the vertical ht. from wall plate to the ridge.
Spans upto 5m

14. DOUBLE OR PURLIN ROOFS Rafters- rest at the ends on wall
Purlins- intermediate supports
Spans upto 5.5 m.

15. TRUSSED ROOF
A number of straight members connected in the shape of triangle and forming a frame is known as truss.
Truss are provided at regular interval of about 3m along the length.
Used for the span more than 5m.

16. KING-POST TRUSS King post- central post Struts- inclined members
Principal rafters- support the purlins
Spans- 5 to 8 m.

17. QUEEN-POST TRUSS 2 vertical posts Straining beam 2 struts
Straining sill
Spans- 8 to 12 m.

18. MANSARD TRUSS Combination of king & queen post trusses.
Upper portion- king post truss
Lower portion- queen post truss.
Upper pitch- 30 to 40 degree
Lower pitch- 60 to 70 degree.

19. BELFAST TRUSS/ BOW STRING TRUSS
Thin sections of timber
Top chord – curved
30 m span – if roof covering is light
Rise not more than 1/8th of the span

20. STEEL TRUSSES stronger than wooden truss Very large span (5m to 30m)
KING-POST STEEL TRUSS
COMPOUND FINK & COMPOUND HOWE’S STEEL TRUSS
ADVANTAGE:
stronger than wooden truss
Very large span (5m to 30m)
Easy to construct
Fire-proof
More rigid
Permanent
More economical

21. STEEL TRUSSES…..Cont 1 Likely to get rusted
DISADVANTAGE:
Likely to get rusted
Need anti corrosive paints.
Periodical maintenance required.
USES:
Building with large span
Building with no intermediate columns.
Place of heavy rainfall of snow fall.

22. COMPOSITE TRUSS Timber and steel Tension members – steel
Compression members – timber
Light and economical

23. FLAT ROOFS
It is one which is either horizontal or horizontal with slope less than 10°.
TYPES OF FLAT ROOFS:
Madras terrace roofs
Reinforced cement concrete slab roof

24. MADRAS TERRACE ROOF

25. MADRAS TERRACE ROOF

26. REINFORCED CEMENT CONCRETE ROOF
Easy to cast
Very smooth surface
Length / width > 2 – one way
Length / width < 2 – two way

27. CURVED ROOFS
Modification of pitched roof and are frequently employed in modern age to cover large areas.
Useful for assembly halls, recreation centres, factories, monumental works
Pleasing appearance
Types
Shell roofs
Domes

28. NORTH LIGHT SHELL ROOF Mostly used in Where good day light id desired
Factories
Work shops
Where good day light id desired

29. BARREL VAULT SHELL ROOF
Long multiple cylindrical shell
Feather edge beams
Where day-lighting is not must

30. DOMES Semi-elliptical or semi-spherical Uniform or varying thickness
Brick, stone, steel, wood, concrete or tile