Insulation For Between Roof Rafters

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

Insulation for between roof rafters.

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. 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. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

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. A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel. Being lightweight they do not impose significant additional loads on existing structures. 7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier.

Consider using high density r 30 batts which are as thick as r 25 batts but fit into 2x10 framing. 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.