Roof Deck Insulation

There are different roof decks that require different insulation techniques.

Cold roofs have insulation between the rafters, allowing for ventilation space below your roof deck. Install baffles or make sure there’s 1" minimum of airspace between the roof deck and insulation.

Hot roofs are insulated above the rafters. Air sealing hot roofs is critical. Because the insulation is so close to the roof and you want to avoid unwanted moisture buildup, these roofs will need to be completely sealed off.

Vented Attics have insulation installed underneath the roof deck, in direct contact with the decking. Ceiling insulation is then installed on the attic floor. Make sure there is adequate air flow from the eave vents to the attic area. R-19 insulation is typically installed in the vented attic application underneath the roof deck.

For cathedral ceiling applications, make sure there is a minimum of a one inch (1”) air space between the insulation and the roof deck. An insulation baffle is often used to ensure this air space is created.

Unvented Attics have R-38 Integrated Roof Deck (IRD) insulation installed underneath the roof deck. No insulation is installed on the ceiling or attic floor. See the 2018 International Residential Code (IRC) for use of air permeable insulation in unvented attics in IECC climate zones 1, 2 & 3. Ensure the attic area is air sealed including the roof deck, ridges & valleys, and connections between the roof and walls (eaves).