Insulation Roof Eaves

A minimum ventilation gap of 25mm is to be provided over the loft insulation to allow sufficient ventilation at the eaves.

Insulation roof eaves.

Insufficient insulation at the eaves is a common contributor to ice dams and there s no simple solution for this. To be truly effective insulated areas must be tied down to the roof itself at the eaves. 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 have a wall ceiling roof construction whereby you need to insulate the ceiling up to the roof membrane then you have to install rafter vents to allow air to continue to flow.

This is the point where the roof meets the walls of the house and it s one place where small gaps and cracks are commonly found. The best approach in these situations is to use an insulation with a higher. For the same reason insulation shouldn t touch the roof s underside. Achieving these r values with cellulose or fiberglass requires at least 11 inches of insulation for r 38 or 14 inches for r 49.

The materials used to insulate under the roof include batts of mineral or glass wool insulation held in place by battens of wood attached to and across the rafters. Everywhere but climate zone 1 building codes require the installation of ceiling insulation rated at r 38 or r 49. Install raised heel trusses or use another roof framing method that allows space to install insulation over the top plates of the exterior walls or install high density insulation to achieve an r value that meets or exceeds code minimums for attic insulation. Detail to show the buildup of new loft insulation to the underside of an existing eaves installed internally to allow ventilation of the existing roof over the new insulation.

In most of the u s. Design the roof to allow full insulation over the top plates of the exterior walls. You need ventilation in the attic a good crossflow of air will keep the attic space dry.