In the opinion of celotex a hybrid solution presents an unacceptable risk of harmful condensation and should be avoided by building designers.
Celotex warm roof construction details.
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.
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Our warm roof construction no ventilation consists of 100mm joists 18mm plywood breathable membrane 50mm celotex insulation battens and slate roofing.
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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Saint gobain construction products uk limited trading as celotex registered in england.
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.
Another key advantage of specifying a pitched roof is the ability to provide a very high level of thermal performance in these roof types whether you re looking to insulate at joist ceiling level for a cold pitched roof or at rafter level if a living area within a warm roof construction is desired.
Where the benefits of over rafter insulation are desired but practical restrictions prove difficult to overcome you may consider insulating between and over rafters.
Celotex offer pir thermal insulation boards in various thicknesses for new build and refurbishment applications for both the commercial and domestic sectors.
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.
Lady lane industrial estate hadleigh ipswich suffolk ip7 6ba.
Insulation uk polyisocyanurate pir foam boards are lightweight.
A warm roof design with the insulation laid over the structural timbers remains the preferred option to a cold roof design.
A warm roof does not need cross ventilation and lends itself to better detailing at junctions with other elements to address linear thermal bridging.