Insulating Low Pitch Attic

Eric dymond lives in a 1920s baltimore row house that needs a new roof.

Insulating low pitch attic.

Rigid board insulation is the most common type of insulation used in low slope commercial roofing. Plan to pull up the flooring and layer new insulation on top of the old. 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. In warm climates zones 1 through 4 low density open cell spray foam insulation is the typical choice since it is vapor permeable and will allow drying of the exterior sheathing and roof framing if they happen to get wet via diffusion into the interior of the building.

But if the floor is covered in plywood you can t stuff enough insulation beneath it to do the job sufficiently not even in warm climates. Stage 2 of insulating a low slope roof. There are lots of ways to insulate a low slope roof and most of them are wrong. Insulfoam sp is specifically designed for low sloped roof applications that employ mechanically fastened or ballasted tpo pvc and epdm as well as low sloped built up modified bitumen and fully adhered single ply roofs that incorporate cover boards or slip sheets.

If the roof is vented the ceiling must be air sealed to prevent moisture laden air from reaching the attic. As this requires fitting insulation above the rafters the roof covering will have to be removed in order to fit the insulation. Although some builders insulate a low slope roof with the same techniques used for a house with a big attic they should be using a different approach. Insulate the walls carefully and effectively so that you don t wind up with further problems down the road.

Currently the built up asphalt roof is installed over homasote or something similar and a roof deck made of wood planks. He plans on replacing the low slope built up roof with an epdm membrane and the question is how to insulate it correctly. To create a warm pitched roof insulation such as kingspan kooltherm k7 pitched roof board should be fitted between and over the rafters. It is made from cellular plastic or fibrous materials and pressed into boards.