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Most of Maine's aging housing stock has significant opportunities to improve energy efficiency.
Air sealing around the chimney and sealing and insulating the attic hatch probably provide
the quickest return on investment.
The opening around the chimney needs to be sealed with metal and high temperature caulk. The chimney is then wrapped with mineral wool before additional insulation is installed.
A dam is built around the attic hatch to keep the added insulation from spilling out. Then an insulated cover is installed. The cover has weather stripping around the edges to form an air tight seal and hooks to hold it tightly in place.
Some other big offenders for air leakage are pull down stairs like the one shown to the right and recessed lights penetrating the attic. Even the new IC/AT (Insulation Contact/ Air Tight) recessed lights cause significant losses. We can install light covers to minimize the air leakage, but they still create a thin spot in the insulation. We treat the stairs similar to an attic hatch. We build a dam around the perimeter and then install a sealed and insulated cover.
All plumbing and electrical penetrations through the attic flat need to be sealed with caulk or canned foam. Then more insulation should be added to bring the attic up to R50. We generally accomplish this with 15" of blown in cellulose. R49 is the minimum recomended insulation value for an attic in this climate zone. Increasing this to R60 is cost effective.
The next target of opportunity is usually the basement. This surprises many people, but houses often lose 30% of their energy through the basement walls. Concrete is a very poor insulator. The solution we generally use is to apply closed cell polyurethane foam to the exterior walls covering the rim joist and going down the wall to 2' below ground level. In addition to insulating the walls, the foam also seals any air leaks between the sill and the foundation.
Many basements in Maine also have moisture issues. The picture shown is of a crawl space that had a dirt floor. Even though the dirt may appear to be dry, moisture is continually evaporating from the ground. As we tighten up the air leaks in the house it becomes important to control the moisture at its source. We use EPDM rubber roofing for this job. EPDM is .060" thick which makes it extremely durable and it comes in a 20'x50' sheet which allows us to complete the installation with minimal seams. As you can see in the picture, the seams and edges are sealed with closed cell spray foam. In high traffic areas, we use a flexible caulking to seal the seams.
Maine law requires that all foam products in an occupiable space are behind a 15 minute thermal barrier. Generally this is accomplished by covering the foam with 1/2" drywall. In basements, drywall is not a practical solution. In basements, and other areas that would be difficult to install drywall, we apply an intumescent coating which provides the required 15 minute thermal barrier. The coating is in the form of a paint that is sprayed on after the foam has cured.
The next area to address are the exterior walls of the house. If the walls have no insulation in them, we can fill the walls with dense packed cellulose. This process is only effective if the wall cavities are currently empty. We refer to the process as Drill and Fill. A 2-9/16" hole is drilled in to each wall cavity. A hose is inserted down to the bottom of the cavity and cellulose is installed and packed to a density greater than its natural settled density. This ensures that the product will not settle over time. Then the hose is inserted to the top of the cavity and the process is repeated. After the cavity is filled, a styrofoam plug is placed in the hole. The proces can be accomplished from either the outside or the inside of the wall. Because this process is highly invasive, we suggest that it be accomplished when the wall is already being disturbed for some other reason. Combining a Drill and Fill with a painting or siding job makes the process more cost effective.