Pitched Roof Insulation Between Rafters

Ballytherm insulation may be used to form warm pitched roofs when applied between and below the rafters.

Pitched roof insulation between rafters.

The thickness of roof insulation is determined by the u value requirements. The insulation can be installed between the rafters and underneath the rafters to extend the thermal envelope up along the pitch of the roof allowing for a new heated room within the loft space. It is common to use the same thickness of insulation between the rafters as you have used above the rafters. The table below is based on a typical warm roof construction with insulation above and between the rafters.

This roof type will require a breathable membrane like kingspan nilvent to be. Applying a layer of insulation beneath the rafters avoids the use of long fixings and enables all the insulation to be applied from inside the roof. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. A sheet vapour barrier fitted to the inside of the rafters not required if the insulated plasterboard incorporates a vapour barrier.

To create a warm pitched roof insulation such as kingspan kooltherm k7 pitched roof board should be fitted between and over the rafters. This popular application requires some careful design considerations to minimise the risk of interstitial condensation and guidance on how to meet. This method is well suited to new build projects and to refurbishments where the roof. Arguably the most popular pitched roof solution installing insulation between and under the rafters uses the depth of the structural timbers to best effect.

Sheet insulation fitted between the rafters the thicker the better but the size of rafter may limit the thickness possible once an allowance has been made for the required 50mm 2 inch air gap. Kingspan kooltherm k7 pitched roof board is a premium performance rafter level insulation for ventilated or unventilated pitched roofs. If making a warm pitched roof construction you should opt for some type of rigid insulation boards such as kingspan k7 pitched roof board orcelotex xr4000 pir insulation boards which can be installed both between and over the rafters and offers a level of fire resistance if important and applicable. As this requires fitting insulation above the rafters the roof covering will have to be removed in order to fit the insulation.

An efficient room in a roof in a new build property where over rafter insulation is not desirable. Please note that these boards require a. Go with insulation between and over or between and under the rafters.