By: Dale Kerr
With winter just around the corner, it’s time to start planning for projects that will reduce home heating costs. Insulation is usually the first thought. Air sealing should be a close second.
Two critical areas of the home to insulate are the attic and basement. Each area lends itself to a different type of insulation product.
Before adding any insulation, check the attic for air leakage, recommends Jim Bunting, technical sales manager for Canam Building Envelope Specialists Inc. Warm air from inside the house can leak directly into the attic around recessed light fixtures, exhaust fans, the attic hatch and penetrations such as vent stacks, and can condense on the cold underside of the roof, which can lead to wood deterioration.
Often not considered is the fact that air can also leak into the attic indirectly via openings in the walls, such as electrical receptacles and around baseboards. Foam gaskets can be used under the cover plates to help seal electrical receptacles, and depending on their size, an acrylic latex sealant or urethane foam can be used to seal leakage openings into the attic.
The great advantage of foam insulation is that it seals and insulates. Many insulating/sealing jobs around the house can be accomplished with small cans of one-component spray foam or with larger froth-paks of two-component foam, such as in the case of sealing and insulating the spaces between the second floor joists in a storey and a half house, a major source of attic air leakage.
When insulating the attic, be sure the soffit is kept clear of insulation. Air circulation from the soffit is necessary in removing any humid air that might still escape into the attic. Vents installed between the rafters are available to ensure the required air space is maintained. Bunting also recommends ensuring that the soffit is actually vented, as he has seen cases where vented aluminum soffit panels are installed directly on solid (unventilated) wood soffits.
Recessed, or potlight, fixtures should not be directly insulated unless specifically designed for such use, as the insulation could cause heat to build up, creating a potential fire hazard. The construction of an airtight drywall box around the fixture is usually recommended to allow heat from the potlight to be dissipated.
For basements, rigid or semi-rigid insulation is most appropriate. There are two options when insulating a basement wall—inside and outside. According to Dr. Kim Pressnail, associate professor of civil engineering at the University of Toronto, outside is the best way to go. Insulating on the outside also provides an opportunity to address water penetration issues, allowing the installation of drainage tile, repair of wall cracks, and application of waterproofing or dampproofing. While the National Building Code of Canada requires a drainage layer next to the wall, Pressnail recommends going further with the use of a filtered drainage layer, especially in fine-grained soils. "Without the filter cloth, during the service life of the building, fine particles of soil may accumulate behind the drainage layer rendering it ineffective and causing water to leak into the basement," Pressnail says.
While exterior basement insulation is the preferred approach, if you must insulate on the interior, Pressnail warns that there will be condensation on the basement wall and you must plan for it. To avoid deterioration of studs or strapping, he recommends keeping them away from direct contact with the basement walls by installing extruded polystyrene insulation to the back of the studs, or alternatively to the entire wall. He also recommends keeping the bottom plate off the basement floor in a similar manner and always keeping the drywall about 50 mm off the floor.
Pressnail says not to insulate the interior of a block basement wall in frost-susceptible soil, such as silt. Interior insulation will cause the exterior of the block to be cold, and adfreezing—where frost in the soil adheres to the exterior of the block—can occur. The combination of frost heave and adfreezing may cause the blocks to displace.
While insulating and air sealing will reduce home heating costs, it is often not possible to justify the expense of such projects by cost-savings alone; the simple payback of many insulation and air sealing jobs can be many years of comfort.
Here are some simple maintenance projects that you can recommend to your clients that require minimal effort and utilize tools many will already have in their toolboxes.
Install a programmable thermostat. A programmable thermostat allows the furnace setpoint to be lowered when additional heat is not needed, such as when the homeowners are away at work or asleep in bed. Different models allow for seven-day per week scheduling, weekday/weekend scheduling and even multiple cycles within a day. Discuss the needs of the homeowner before settling on the appropriate model.
Clean gutters. Removing leaves and other debris from the gutters will help ensure that water will drain freely in the eaves.
Install snow-melting cables. Using electric cables on the roof will help prevent ice damming.
Change furnace filters. Reusable filters can simply be washed off with a hose, while paper filters should be replaced. A clean furnace filter not only removes particulates from the air better than a clogged, dirty filter, it also improves furnace performance by providing less resistance to the flow of air. While HEPA (High Efficiency Particulate Air) filters are the most effective filters at removing particulates, they also provide the most resistance to air flow and can compromise the performance of a furnace not designed for their use.
Reverse the direction of ceiling fans. Cooler air is denser than warmer air and as a result, temperature stratification may occur within a space, whereby the warmest air is at the ceiling and the coolest air is at the floor (near the occupants). In the summer, ceiling fans should be set to push air downwards, creating a cooling draft. In the winter, setting the ceiling fan to circulate air upwards avoids the cooling draft while gently mixing the warm air with the cooler air, resulting in a more uniform room temperature.
Up to 25 percent of the heat energy lost from a house can be through the windows and doors. George Torok is a technical consultant for the Siding and Window Dealers Association of Canada (SAWDAC), and National Capital Region Manager for GRG Building Consultants Inc. He says that winterizing windows and doors can help save energy and suggests starting with simple improvements to reduce air leakage, such as adjusting or replacing hardware and adjusting sash back to square.
Next, Torok recommends replacing weatherstripping and door sweeps. While it is usually impossible to find an exact replacement, the important thing, according to Torok, is to replace "like with like" (i.e., replace compression gaskets with compression gaskets or brush weatherstripping with brush weatherstripping) and to not worry if the replacement cannot be installed in the kerf like the original—securing replacement weatherstripping to the face of the kerf or the side of the jambs is an acceptable practice.
Torok also recommends sealing/insulating the perimeters. If possible, remove the interior trim and any insulation stuffed into the gap between the studs and the window/door frame. Spray a low-expanding one-component polyurethane foam made specifically for door and window installation into the gap in two passes. The first pass should be tight against the outside trim or brick mold and should be no more than 25 mm deep. Allow the foam to cure before applying the second pass. The second pass should also be no more than 25 mm deep, and should be at the inside of the gap, such that there is an air space between the two layers of foam. The use of a professional-quality foam gun will help immensely with controlling the depth of the second layer, Torok says. "Following this procedure is extremely important, as applying too thick a layer of foam or not allowing the first layer to cure before applying the second layer can result in too much expansion of the foam causing bowing of the window or door frame." If it is not possible to remove the interior trim, Torok recommends simply applying an acrylic latex sealant around the perimeter of the casing.
Installing solar window film to help reflect some of the heat back into the house; Installing shrink wrap to the window frame to create a still air space that improves the heat flow resistance of the window; and, Replacing the windows, which can be particularly cost-effective if the windows are single glazed.