How To Insulate Roof Rafters With Celotex

Install the insulation flush with the bottom of the rafters making sure that it does not fill the entire rafter depth.

How to insulate roof rafters with celotex.

Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. 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. Not insulating between the rafters above this space thus creating a huge air space. I wish to use celotex 50mm between the rafters 70 x 150mm up to the 2m height.

For example if the space beneath the rafters is going to be used for a living area then you will need to insulate the roof rafters. Being lightweight they do not impose significant additional loads on existing structures. We used kingspan thermapitch tp10 zero odp which is a 100mm thick rigid board. If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of.

The saint gobain insulation uk u value calculator gives you instant access to calculating a proposed insulation thickness and product options or giving an indicative calculation on a proposed construction detail. Depending on the specifics of the roof it may be possible to fully fill the rafter depth or in most cases leave a 25mm or 50mm air gap between the top face of the insulation and the. Ensure that the insulation boards fit tightly between the rafters. Although there are many different circumstances that may call for insulating roof rafters the means to determine the necessity for insulating rafters remains the same.

Insulate the flat roof 75mm celotex fixing plasterboards to the cross supports creating a ceiling. Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market. Where the benefits of over rafter insulation want to be enjoyed while still creating a useable room in the roof space it s possible to insulate over and between the rafters. Due to the thermal bridging effect of the timbers the overall thickness of insulation used to achieve a low u value is not as efficient as over rafter insulation only.

There will also be kooltherm k7 pitched roof board between the rafters image credit. Alternatively battens can be secured to the underside of the.