Garage Roof Rafter Insulation

The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow.

Garage roof rafter insulation.

In a warm roof structure the insulation is placed above or above and between rafters in order to avoid heat loss and energy transfer. Ibc dictates acceptable placement and composition of roofing materials in chapter 15 but describes required thermal efficiency of the roof in chapter 13 which references the international energy conservation code iecc the minimum required thermal resistance varies. It pays to insulate your garage if you re adding heat whether on a permanent or as needed basis. There should be a continuous ridge and soffit ventilation.

Garages built without attics are also prime candidates for insulation into rafter bays the name for those spaces between rafters. For the same reason insulation shouldn t touch the roof s underside. In reality insulation merely slows the transfer of heat through the insulated barrier wall ceiling floor etc. Opening vents in the soffit would allow air to flow from the low edge of the roof up along each channel between the rafters and up to your ridge vent.

Roof insulation configurations for unvented rafter truss assemblies. Make sure you have enough ventilation on your roof as well. This netting serves to hold the blown insulation usually recycled newspaper inside the rafter pockets until such time that ceiling materials can be installed over the insulation. Covering up the soffit vents with loose fill or batts which can happen if you stuff insulation along the eaves is a huge no no.

Blown cellulose insulation will require the installation of netting over the rafter pockets. You can either install faced batting insulation which has a paper. If you are insulating the garage ceiling not only by the truss level but also up by the roofline then you must leave at least 1 1 2 to two inches of air between the fiberglass and the underside. If you re not adding heat there s little point in insulating.

Images courtesy simpson gumpertz heger.