ROOF - Building Materials short notes and previous year questions

ROOF

• Heavy rainfall / snowfall : sloped roof 

• Normal rainfall : flat roof 

• Architectural : curved roof 

TERMS 

1. WALL PLATE : transfer load from inclined member to vertical column 

2. TEMPLATE : distribute the load over a larger area 

3. HIP : if external angle > 180 

4. VALLEY : if external angle < 180 

5. PRINCIPLE RAFTERS : carries entire load of truss or roof 

6. COMMON RAFTERS : carries load of roof covering materials 

7. HIP RAFTER : rafter connecting hip points 

8. VALLEY RAFTER : rafter connecting Valley points 

9. JACK RAFTER : rafter smaller than common rafter 

10. VERGE : edge of the gable in a pitched roof 

11. BARGE BOARD : wooden plank connecting eaves board and ridge

KING POST TRUSS  

• Span 5 - 8 m 

• Pitch 30 - 40 

• King post carries tension loads 

• Struts carry compression loads 

• Joint connecting principle rafter and king post : mortice and Tenon joint 

QUEEN POST TRUSS

• Span 8 - 13 m 

• Pitch 60 - 70 

• Queen post carries tension load 

• Struts carry compression loads 

• Straining beam carry compression loads

STEEL TRUSS 

• Span > 12m 

• Economical & safe 

• In compression member spacing of rivet : 15 cm 

• In tension member 20 m 

MANSARD TRUSS ( 18 M ) 

• Lower part : queen 

• Upper part : king

BELFAST/BOWSTRING/LATTICED ROOF (30M) 

• Central rise : 1/8 span

COMPOSITE ROOF 

• Combination of steel, timber, iron etc

PREVIOUS YEAR REPEATED QUESTIONS BASED ON ROOF