Roof Insulation Between Rafters

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

Roof insulation between rafters.

It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. 7 staple sheets of 6 mil plastic over unfaced insulation to create a vapor barrier. 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. Although there are many different.

Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. Whether you need to insulate your roof rafters will depend on what you intend to do in the space directly beneath the rafters. Insulation can be installed between the rafters using a ventilated roof construction or an un ventilated roof construction. 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.

We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. Unfaced insulation has no tabs and stays in place with friction between the fiberglass and the rafters. Water is insulation s enemy. 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.

The decision on which method to use is usually dependent on the sarking or underlay. 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. Box out light fixtures.

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

Being lightweight they do not impose significant additional loads on existing structures. In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face.