Insulating Sloped Roofs

Insulating a sloping roof.

Insulating sloped roofs.

Types of low slope roof thermal insulation rigid board insulation. Dual purpose structural deck and insulating planks. Currently the built up asphalt roof is installed over homasote or something similar and a roof deck made of wood planks. Rockwool comfortbatt is a stone wool insulation that provides reliable thermal resistance over time.

A layer of spray polyurethane foam can be installed against the underside of the roof sheathing with the rest of the rafter cavity filled with air permeable insulation. There are lots of ways to insulate a low slope roof and most of them are wrong. Ceiling insulation refers to any type of insulation installed within the floor nearest to the roof structure of the home. For the same reason insulation shouldn t touch the roof s underside.

The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow. If you want to vent a low slope roof here s what you need to do. In older buildings the usual method is to install fiberglass batts or cellulose on top of the leaky ceiling with a gap of a few inches or sometimes a few feet between the top of the insulation and the roof sheathing. You must meet the same minimum code requirements for the spray foam layer and the total assembly as for the rigid foam plus air permeable insulation approach.

It s worth insulating the sloping insides of a pitched roof in order to conserve heat if the space is to be used for anything except simple storage. Specify roof trusses or conventional framing deep enough for 12 in. Of insulation plus room for an air gap of. Rigid board insulation is the most common type of insulation used in low slope commercial.

For the past 10 years energy code cycles have focused on wall assemblies. Eric dymond lives in a 1920s baltimore row house that needs a new roof. He plans on replacing the low slope built up roof with an epdm membrane and the question is how to insulate it correctly. Roof insulation refers to the practice of installing insulation on the roof slope both above and below the rafters.

Dual purpose structural deck and insulating planks are comprised of. Wood framed sloped roofs have been a common means to provide shelter and protection from the weather for centuries but high performance building enclosures often focus on wall designs rather than roof designs.