Warm roof

[selfbuildy]

Planning to use attic as a room.

Roof construction is 9inch rafters covered with a permeable membrane,battons then slate. Ventilation is 25mm over fascia vent.

My question is about insulating rafters.What are my options. Am i supposed to totally fill void or should there be an air gap

Thanks in advance

 

[RobC316]

Well, the best option would be to fit insulation between the rafters and then have a vapour barrier on the warm side of the insulation as this will prevent the passage of moisture through the structure.

You could leave an airgap between the roof covering and the insulation as this would provide some degree of ventilation, it is in one of the approved documents of the building regs - not too sure how much air gap you must leave.

Would be much easier to use vapour barrier.

 

[markie]

50 MM air gap

 

[joemanzini]

Going through the same process myself,but wondering if I need warm roof /cold roof, this is a site I found, it appears to be a cold roof, yet ends up as a suggested useable/ storage space.
http://www.above-it-all.co.uk/lofts/pictures/03.html
J