How To Insulate Roof Rafters With Celotex

Being lightweight they do not impose significant additional loads on existing structures.

How to insulate roof rafters with celotex.

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. I wish to use celotex 50mm between the rafters 70 x 150mm up to the 2m height. 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. 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. We used kingspan thermapitch tp10 zero odp which is a 100mm thick rigid board. Cut the insulation boards to size using a sharp knife or fin toothed saw. Ensure that the insulation boards fit tightly between the rafters.

Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market. Not insulating between the rafters above this space thus creating a huge air space. Kingspan with a warm roof the usual process is to split the insulation into two layers. 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.

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

Alternatively battens can be secured to the underside of the. Insulate the flat roof 75mm celotex fixing plasterboards to the cross supports creating a ceiling.