Our warm roof construction no ventilation consists of 100mm joists 18mm plywood breathable membrane 50mm celotex insulation battens and slate roofing.
Celotex warm roof construction details.
Where the benefits of over rafter insulation are desired but practical restrictions prove difficult to overcome you may consider insulating between and over rafters.
In the opinion of celotex a hybrid solution presents an unacceptable risk of harmful condensation and should be avoided by building designers.
Tel 44 0 1473 822093.
A fully warm roof construction is recommended and where this is not practical a cold roof can also be considered.
Francis wood july 23 2015 at 12 41 pm.
If the roof has insulation over the joists warm roof construction and you choose to insulate the underside of the joists steps would need to be taken to make sure that the required ventilation.
As mentioned before celotex gs5000 has an integral vapour control layer and blocks warm moist air rising into the pitched roof structure.
Fixed over the rafters of a pitched roof they can help to achieve the required u value in just a single layer.
We would like to show you a description here but the site won t allow us.
The building detail is for illustrative purposes only.
A warm roof design with the insulation laid over the structural timbers remains the preferred option to a cold roof design.
The roof will need to be checked to see if there is any insulation either within the joists or on top of the joists as a warm roof construction.
A warm roof does not need cross ventilation and lends itself to better detailing at junctions with other elements to address linear thermal bridging.
Saint gobain construction products uk limited trading as celotex registered in england.
Insulation uk polyisocyanurate pir foam boards are lightweight.
However warm moist air by its very nature will always find the passage of least resistance so the use of a 50mm ventilated air gap between the joists in conjunction with a vapour control will effectively.
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