Insulating Underside Of Roof Deck

Insulation and air barrier are applied directly to the underside of the roof deck are common in applications where designers are seeking cost effective and energy efficient roof assemblies.

Insulating underside of roof deck.

Low slope and steep slope unvented roof systems i e. Insulating the underside of deck. Install insulating sheathing above the roof deck on existing homes. This construction approach was first used in the 1970s and it has been implemented much more widely since it was first included in the international code council s icc model building code in 2007 irc section 806 4.

Staple plastic or foam baffles to the roof sheathing near the eaves to keep the material away. It is about three feet off the ground and has mesh stapled to the underside to prevent bugs from making their way in. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. For the same reason insulation shouldn t touch the roof s underside.

Remove existing roofing and non adhered underlayment to expose roof sheathing. This retrofit assembly is appropriate for homes with conditioned attics or where the retrofit is intended to create a conditioned attic. If you re insulating from scratch put the right vapor barrier in the right place. Fiberglass insulation is installed between the rafters as shown schematically below.

In addition to installing the foam board on the underside of the roof deck you can attach it to the bottom edges of the rafters in the same manner you would hang drywall. However architects of these compact roof assemblies must consider vapor permeance and arrangement of the materials to produce acceptable hygrothermal performance and low risk of condensation in the resulting conditioned attic space. Our deck has been updated to a three season porch. You can then install.

A wood deck roof system. This type of system can also be found in low slope residential buildings in inner city areas.