Roof Insulation Between Rafters

Unfaced insulation has no tabs and stays in place with friction between the fiberglass and the rafters.

Roof insulation between rafters.

Insulation can be installed between the rafters using a ventilated roof construction or an un ventilated roof construction. 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. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face.

7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier. Although there are many different. 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. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.

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. Whether you need to insulate your roof rafters will depend on what you intend to do in the space directly beneath the 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. Water is insulation s enemy.

We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. Modern u value targets mean installing insulation between rafters only is rarely a viable option. Being lightweight they do not impose significant additional loads on existing structures. Consider using high density r 30 batts which are as thick as r 25 batts but fit into 2x10 framing.

You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters. For example if the space beneath the rafters is going to be used for a living area then you will need to insulate the roof rafters. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow.

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. A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel.