Insulation For Between Roof Rafters

7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier.

Insulation for between roof rafters.

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. 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. Consider using high density r 30 batts which are as thick as r 25 batts but fit into 2x10 framing. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings.

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. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

Modern u value targets mean installing insulation between rafters only is rarely a viable option. 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.