The most important factor of home air sealing is that it keeps the conditioned air in the house, whether it's heated or cooled air, and in turn keeps energy costs lower and makes a home more comfortable, says Ron Cowgill, CR, CKBR, GCP, president of D/R Services Unlimited, Inc., a full-service remodeling firm. In part 2 of NARI's green remodeling series, Cowgill gives advice on ways to make sure a home is sealed correctly.
A home is never going to be sealed completely tight, but the real purpose of air sealing is to control where drafts are coming from to get a hold of the problem and adjust it as needed. That way, if a home is sealed well, an air handler can introduce fresh air into a home and control the air infiltration, rather than just having it come in from everywhere.
"We use a thermal imaging camera before we drywall," says Cowgill. "You can also do a blower door test before you start the remodeling project and then do a blower door test after. That will help determine where those leaks are and that you're leaving the house tighter than when you started."
Components of air sealing that lead to a more efficient home are installing insulation; caulking gaps around the windows and doors; and making sure the windows and doors are in good shape. Those are generally the areas that are addressed. For instance, with proper attic sealing, it is important to seal any penetration coming up through the ceiling into the attic like electrical lines, recessed lighting or plumbing pipes — making sure to foam around these leaks, and then put insulation on top of it.
Other areas that Cowgill says most people don't think about are basements, crawl spaces and all around the joist pockets, right above the foundation where the joists sit. Forgetting to seal these areas properly can create a chimney effect. By letting air come in from below, that heat will still want to rise and will go right out the attic. If sealed first it will help to retain heat in the home.
"Understand that it's probably impossible, especially in a remodeling project, to completely seal a home," explains Cowgill. "A guy I work with a lot says, ‘When you shut the front door and your toilet flushes, your house is too tight.' Until that happens, you don't have to worry about sealing the house up too much."
A few of the important aspects of insulation to consider in regard to green remodeling, according to Cowgill, are making sure the R-value of the insulation is appropriate for the application; potential off-gassing issues with products that contain formaldehyde or other chemicals; and if using a foam insulation, you need to know if it is an open-cell or closed-cell foam which effects the R-value, installation and air penetration.
"One mistake that can be made in regard to air sealing is thinking you can just throw some fiberglass insulation in the wall and it will be enough to make it good," adds Cowgill. "It's insulation, but it's not designed to stop drafts. Fiberglass insulation is not an air sealing material, but rather slows air down and filters it as it comes into your house."
Cowgill says that no matter what type of insulation is being used it is important to use expansion foam around the windows, caulking bottom plates to the subfloor, and caulk between any framing members that may be close together, like two studs sitting next to each other, that are too tight to get insulation between. That way it seals all those areas where there might be some air infiltration.
Making the right choice
Current tax credit guidelines are a great way to make sure the windows are the right choice for a greener project says Cowgill. That will drive a good quality product. Also, it is important to follow the installation guidelines because it's the simplest thing to do to ensure proper sealing. Companies that manufacture house wraps and windows are backing this up with online videos and instructions to emphasize this point.
"The way that windows are flashed today are completely different from the way we did them 10 years ago," says Cowgill. "A lot of guys are still putting them in the same old way and channeling water and air into the building. So go back and read the installation guidelines and see the changes"
To incorporate a more sustainable air sealing what can be done to start introducing better air sealing into projects. For Cowgill's company, about five years ago they just decided they weren't using fiberglass insulation anymore. All of their projects are bid with closed-cell foam. Other simple items to start with that don't cost much include caulking and sealing where all the framing timbers meet, and foaming around windows and doors.
"Just pick up one thing at a time, introduce it into your system and then it becomes second nature," adds Cowgill. "I think that if everyone would just do a thermal scan and blower door test before starting a project, and seeing where all their leaks are coming from, it would just completely change their attitude."