Insulate & Air Seal Drafty Kneewall in Enfield, CT
Challenge
A kneewall space is created when a finished room is built within a sloped roof. A short wall called a "kneewall" forms a triangular space which mar or may not be accessible with a short door or access panel. The floor of the kneewall space forms the ceiling of the room below it. The floor and kneewall space side with exposed fiberglass batts. Since fiberglass does not stop air flow, the insulation does next to nothing to air seal and insulate. The floor of the upper level, the ceiling of the lower level and the kneewall are all cold in winter and hot (from radiant roof heat) in the summer. The kneewall space is not suitable for storage since it is dusty and very cold or hot.
Solution
Blocks of SilverGlo™ foam insulation are installed between the ceiling joist bays. Outside the blocks, the surface of the ceiling is sealed with sprayed foam or SilverGlo™ foam. (Fiberglass insulation may be installed on top). SilverGlo™ foam insulation is installed under the rafters up to the kneewall and sealed at the top with foam sealant. SilverGlo™ is expanded polystyrene foam insulation with graphite infused into the foam, which increase the R-value by 24% compared to regular EPS foam. SilverGlo™ also has a radiant barrier on both sides to reflect roof heat out in the summer and house heat back in during the winter. The addition of this radiant barrier gives some thermal benefit so the insulation isn't left alone to do all the work. After installation, inside air can't get out of the house through the kneewall spaces and outside air can't get in. Insulation is added, with integrity, to the correct surfaces. Results - significantly warmer upstairs room in the winter, cooler room upstairs in the hot weather, less drafts, more comfort, less dust. A kneewall space suitable for clean storage. Lower fuel and electric bills.
