My preference is a warm roof construction with grp.
How to insulate a flat roof with celotex.
Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings.
In order to avoid any problems with harmful condensation we would recommend that you follow the following guidelines given in the building regulations.
Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation.
Alternatively battens can be secured to the underside of the joists and gmw fitted between these in much the same way as between the main roof joists.
Due to a rewire i ve had to remove parts of the plasterboard ceiling and have found that there is no insulation in the roof i can see the roof deck and joists there is no vapour layer and the plasterboard is not foil backed.
Lightweight rigid polyisocyanurate pir foam insulation boards such as those manufactured by celotex are among the most thermally efficient commonly available insulation materials.
You can install celotex insulation between the joists of your flat roof and 80mm would be a good choice though you would normally need a little more if you were working to building regulations.
With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same.
Celotex have introduced three advanced flat roofing solutions featuring cutting edge thinness and thermal performance with solutions for mechanically fixed single ply and built up applications as.
As for insulating below the joists an insulating laminate insulation bonded to plasterboard such as celotex pl4000 or a separate rigid pir insulation board finished with a separate sheet of plasterboard can be securely fixed to the joists to provide an internal finish to the roof.
Depends on what type of construction it is really and which insulation material.
The roof assembly consists of the deck vcl insulation and roof covering.
The test measure both fire penetration and surface spread of flame the results range from the highest ext faa which stands for external surface flat penetration grade a and surface spread of flame a to ext fcd the lowest.
100mm celotex is what building control always want from me for.
Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market.
Celotex polyisocyanurate pir foam insulation boards are easy to cut and handle.
Hi i have a flat roof extension built in the 1970s.
