Roofs Flashcards
What is the typical distance between ceiling joists in a rafter and purlin roof?
400-450mm centres.
What is the typical distance between ceiling battens in a rafter and purlin roof?
400-450mm centres
What is the typical distance between ceiling rafters in a rafter and purlin roof?
400-450mm centres
What is the difference between a gable roof, hipped roof and mansard roof?
A gable roof is where a triangular portion of the wall sits between the edges of a sloping roof.
A hipped roof is where the all roof pitches slope down to meet the walls.
A mansard roof is where each pitch of the roof has 2 slopes with the lower slop at a steeper angle than the higher. The lower slope is often punctuated by dormer windows.
What is the difference between a jack rafter, hip rafter and a common rafter?
A common rafter is any rafter extending from the top of the exterior wall to the ridge of the roof.
A hip rafter extends from the corner of the wall all the way to the ridge, forming the hip of a roof.
A jack rafter is a shorter secondary rafter often used in the construction of a hipped roof.
What is a flitch beam?
A flitch beam is made up of a steel plate sandwiched between two wood beams, the three layers being held together with bolts. Its lighter than a steel beam.
What considerations are required to pitch when slating a roof?
In general the lower the pitch of the roof the greater the lap should be.
This longer lap will help resist both capillary action and wind uplift.
On steeper pitches with free flowing drainage smaller slates may be used.
What type of nails should be used for fixing slates?
Aluminium alloy or stainless steel.
What issues should be considered when replacing a flat roof?
Its age.
The type and extent of defect
Is it safe
The current use
The proposed use
The cost.
What Building Regulation implications are there when repairing a flat roof?
Part L has implications here.
Part L of the Building regulations relates to the conservation of fuel and power
It comes into effect when 50% or more of the roof area is being refurbished.
In simple terms, it means that the thermal efficiency of the whole roof must be upgraded and get as close to the current regulations as possible.
If such an upgrade is not technically or functionally feasible or would not achieve a simple payback of 15 years or less, the element should be upgraded to the best standard that can be achieved.
