Air sealing your home is simply one of the best things you can do to help increase its energy efficiency. It’s the most cost-effective way to make your home more comfortable and less expensive to live in, saving up to ten percent of your annual energy usage.
The exterior walls, ceilings and floors help keep the outside air out and the inside air in. This exterior barrier is called the building envelope. But when you start poking holes in this envelope with windows, doors, lights, and utility lines you create areas for air unintended air to leak into and out of the home.
These leaks not only make a home drafty and uncomfortable, but they can compromise the home’s durability as well. Moisture in the air that is infiltrating the building envelope through this Swiss cheese labyrinth of holes gets trapped inside the walls and over time can cause wood rot and mold problems.
You don’t need any special skills or tools to do some basic air sealing on your home. Along with some simple hand tools - caulking, weather stripping, and spray foam insulation are just about all you’ll need. But knowing where the problem spots are is the most important part of the job.
Think of this article as more of a “where-to” than a “how-to.”
Finding air leaks starts with the obvious and moves into the obscure. The obvious leaks you can see and feel like those around windows and doors. The more obscure leaks happen in areas of the home you don’t usually think of as being trouble spots but they can often cause the biggest problems. You’ll find the biggest energy wasters in the attic and the basement.
The best way to find all of the air leaks in your building envelope is to hire a qualified professional to conduct an energy audit on your home which includes something called a Blower Door Test. The pro conducts this test by closing up the windows and doors and placing a large fan in the opening of one of the doors. This fan is hooked up to a computerized device and a laptop with some pretty high tech software. As the fan runs it depressurizes the house and the technician can determine how much air is leaking into the home and pinpoint where its coming from.
Many states are offering rebates and incentives for you to get this work done because there is a major push in this country to use less energy to condition our homes. Check with your local utility companies to see what programs are available near you. You just might get lucky and find a deal to get an audit free or at minimal cost.
If no program exists or the cost for an audit is not in your budget there are ways to go at it alone.
Focus on the areas that are obvious first. Caulk around windows and doors both on the inside and outside of the house. Use weather stripping in door openings if your doors themselves are drafty. If you close your door on a piece of paper and are able to pull the paper out without ripping it, you’re losing energy.
There are dozens of places where air leakage can occur. Find all of the utility lines such as electrical, gas, phone, and cable lines that poke through the building envelope and seal them with caulk. Be sure you use a silicone caulk labeled for outdoor use.
Outdoor hose spigots, dryer vents, and exterior lighting are all big culprits for air leakage. Any time something penetrates the building envelope it needs sealing.
A clever way to find some air leaks is to use an incense stick. If you shut off your furnace, fans, and air-conditioner on a windy day and walk around with the incense stick you can easily see drafts moving the smoke from the incense stick.
Some of the less obvious places where you find air leakage are the areas where different building materials come together. A good example is where the home’s framing comes in contact with the foundation. Builders often neglect to insulate or seal this area. Fill the spaces between the wood and the foundation with the expanding spray foam insulation you buy in a can. This will require you to head down to the basement or into the crawlspace, but the effort will pay off.
Air leakage doesn’t only happen when outside air leaks in, but also when inside air leaks out. Recessed lighting and attic hatches are hot, or cold spots for this. In the winter the heat in your home rises and will escape through these holes in the ceiling. As the heat rises cold air is drawn in through other leaks around the house. You can caulk around recessed lights with a high-temperature or fire-rated caulk and reduce air loss in attic hatches with weather stripping.
A more obscure example where you’ll find an air leak is within interior walls. Interior walls often have electrical and other utility lines running through them. Sometimes the wires run up the inside of the wall and into the attic through large holes in the top plate of the wall’s framing. Conditioned air will be drawn up through these holes and escape into the unconditioned attic. This may be why you feel a draft next to a light switch or plug outlet. These holes should be sealed with a fire-rated caulk.
After all of this air sealing some people may be worried that it makes the house too air tight preventing proper ventilation. This is very unlikely in older homes, but proper ventilation is extremely important in a home for good indoor air quality.
If you are concerned with making your home too air tight, you may want to consider hiring that professional for a home energy audit after you are done. He may recommend some type of mechanical ventilation to keep the air in your house healthy and fresh.
The best practice for homes today is to reduce all the air leakage and control the ventilation. Take the time to read a good “how to” book to find more places to seal and the techniques for doing so, and help you determine your needs for mechanical ventilation.
If you have ever felt a draft its not just you’re comfort that is compromised but your wallet as well.
Jason Gurskis is a licensed home improvement contractor based in Mystic Island, New Jersey dedicated to making homes more comfortable, durable, and energy efficient.