Roof Insulation Board Between Rafters

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Roof insulation board between rafters.

The usual way to do this is by inserting rigid insulation boards between the rafters. This roof type will require a breathable membrane like kingspan nilvent to be. Modern u value targets mean installing insulation between rafters only is rarely a viable option. In this blog post we will be looking at insulating pitched roofs and why putting insulation just between the rafters isn t a viable solution.

It allows insulation to be installed in a watertight roof either after the roof covering has been fixed on a new build or without disturbing an otherwise sound existing roof covering as part of a renovation. Time to get the insulation finished and get this place warm. As this requires fitting insulation above the rafters the roof covering will have to be removed in order to fit the insulation. To create a warm pitched roof insulation such as kingspan kooltherm k7 pitched roof board should be fitted between and over the rafters.

They should be cut to exactly the right size so they fit snugly and don t allow any draughts through. Where the insulation does not fill the total rafter depth the low emissivity foil facings can gain additional thermal benefit from the air spaces they face into. The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs. The general advice we give is that you should always insulate between and above the rafters or between and under the rafters on our u value calculator we don t give an option for putting insulation between the rafters.

Check out our how to video at the link below. Measure the space between the rafters where the insulation will be placed and cut the insulation boards marginally wider than the space to ensure a friction fit upon installation. To get the required 270mm thickness of insulation you may have to insulate over the rafters as well using insulated plasterboard. When you use solid insulation board to create a warm loft the key thing to remember is ventilation you must keep a 50mm gap between the roof and the rigid insulation board.

Fit the cut quinn therm qr insulation boards tightly between the rafters with the quinn therm branded side facing into the building. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings.