Insulation For Between Roof 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.

Insulation for between roof rafters.

A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel. Unfaced insulation has no tabs and stays in place with friction between the fiberglass and the rafters. Modern u value targets mean installing insulation between rafters only is rarely a viable option. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

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. 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. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. 7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier.

We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. Being lightweight they do not impose significant additional loads on existing structures.