Roof Insulation Board Between 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.

Roof insulation board between 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. Being lightweight they do not impose significant additional loads on existing structures. Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market. Depending on the specifics of the roof it may be possible to fully fill the rafter depth or in most cases leave a 25mm or 50mm air gap between the top face of the insulation and the.

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. 100mm based on 150mm rafters leaving 50mm air flow. Easiest insulation for layperson to install fairly inexpensive r value doesn t fluctuate as with loose fill. Fit the cut quinn therm qr insulation boards tightly between the rafters with the quinn therm branded side facing into the building.

Measure the space between the rafters where the insulation will be placed and cut the insulation boards marginally wider than the space to ensure a friction fit upon installation. There is nothing wrong with that method in princaple is just very tricky hard work and itchy. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall.

In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face. 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. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. Rolls are usually used for long expanses such as length of floor for entire attic while batts are fit between studs in attic rafters.