Want to Reduce AC Leaks? These 3 Simple Fixes May Help You

CNET

a day ago

Summer can be difficult, but if you have an air conditioner, blasting it will get you the much-needed relief. The issue is that running an air conditioner can be expensive. Nobody likes a sky-high energy bill. A recent CNET survey found that over 78% of US adults are worried about rising energy costs.
But it's not all bad news. If you want to use your AC while keeping your energy costs in check, you can. A bit of insulation and air sealing can help, whether you need to cut your utility bill or just maintain your indoor temperature at a comfortable level. The key is to try to seal your home, so you can get started by packing your home's outer 'envelope,' adding some insulation in the attic and tightening ductwork. This is not only true for fixed ACs, but also for portable air conditioners that can help you cool off better this summer.
The idea is to target the most common air leak trouble spots in your home. Finding and sealing them can make a big difference without needing to spend a fortune. Here's how to get started.
Air-sealing the 'envelope'
First, you'll want to start with air sealing the home. Doing this will get you the most improvement with the least money spent. It's also crucial that you air seal your home before doing any insulation. You're wasting your time, otherwise. Fibrous insulation needs an air barrier to work, which is why it's recommended last.
When talking about air sealing the "envelope" of a home, it's important to note the way air behaves naturally in a building. The pattern of air in and out of your home is known as the "stack effect," and it explains why the temperature in your house often feels like it's different on each floor. Heat rises and cold air moves to lower levels -- so warm air leaves your home through the attic and cold air comes in through a crawl space, unfinished basement or other unconditioned lower part of your house.
That's why air sealing the higher and lower levels of your home, in combination with insulation, is one of the best ways to fight air leaks.
Understanding air leaks and how to find them
When a window is drafty, it's obvious. Leaks in attics or crawl spaces are worse for the balance of your home's temperature but they're typically harder to detect. And these areas are going to be the most beneficial in working against the "stack effect." You'll want to air seal window trims, doors, vents, fireplace and furnace flues and other fixtures such as pipes and wires that penetrate the "envelope" of the home.
Windows will often have gaps around the trim and under the sill. To seal these, you can use a caulk gun. Follow the steps below.
Cut the top of the tube of caulk at a 45-degree angle
Use the pin underneath the gun to break the seal and place the tube into the caulk gun
Position the caulk gun and press the trigger as you go along the frame
The 45-degree angle allows the tip to shape the bead of caulk into a neat line as it's applied but it still might need some touching up. You can do this easily with your finger. Don't worry about getting it on your skin, as caulk rinses off easily with water.
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You can also use the caulk gun for a bathroom exhaust fan, floor supply vents and any other crevices. But as far as sealing a flue, you want to make sure to use a fire rated caulk instead for areas that are more combustible to ensure fire safety. And before you air seal a flue, make sure the furnace is off and there isn't a fire going (or you've let it cool off enough).
Sealing windows with caulk
To air seal the front or back door frame, you can add a weather strip. These doors can have a little gap between the door and the outside that's letting air come in. You can pick up a weather strip kit that comes with everything you'll need. Follow the steps below.
Remove any old existing weather strip from your door frame
Measure the side of your door frame and cut the new weather strip to fit. Make sure to cut it from the metal side -- you'll get a cleaner cut
Close the door and make sure it's locked before you install the weather strip (if it's not locked and you install too close, you could put tension on the lock and it could break)
Install the new weather strip -- start with the left and right side of the frame first and then pressure fit the top
Line up the weather strip tightly on the side of the frame, but don't press too hard against the door
Using a drill, put the first screw in the middle, then do the top and bottom next
Repeat the same steps for the other side and again for the top
Using spray foam for larger gaps
For awkward areas where there's a bigger gap or wires in the way, you can air seal these areas with can foam. It's much easier to just spray the foam in these openings and let it expand.
To use the can foam, attach the nozzle to the top and handle with care. This will not come out of your clothes or carpet, which means you don't want to make any mistakes.
Again, leaks in your attic or crawlspace are the most important areas to address. So you can spray the can foam in the openings around pipes and vents, in the crevices in a crawlspace and on the tops of the interior walls in the attic. If you have an unfinished basement instead of a crawl space, you can use caulk or can foam to air seal the rim joist and sill plates.
Sealing the ductwork
If your ducts are leaky and in a space without air conditioning (such as a crawl space, unfinished basement, cellar or attic) wasting money by heating or cooling the outdoors. When you seal it, more of the heat or air conditioning that was supposed to be pumped into your home will stay inside.
Not only that but sealing your ducts will also improve your indoor air quality. If the duct is leaky, it could be pulling in dirt, dust, mold and possibly radon from outside. Sealing the ductwork allows the duct to only suck from air that's already in the house.
To seal the ductwork in a lower space without air conditioning, you can use a mastic sealant. Mastic is good for sealing the joints of the ductwork because it's fluid and can get into hard-to-reach areas. It's also flexible in that it will withstand expansion and contraction caused by temperature changes.
The next part is easy. With a rubber glove, you can literally dip your hand in the bucket of mastic and spread it along the seams, joints and holes of the metal ductwork. Just be careful not to get cut, as metal ductwork can have sharp edges.
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Adding attic insulation
Last but not least, you'll want to insulate your attic space. As previously mentioned, if you insulate your attic before air sealing the attic floor, it's not going to do much for you.
When talking about insulating the attic space, it's important to note that the insulation and air barrier should be continuous and contiguous (meaning they touch). The continuous part is that it's more effective to have 6 inches of insulation everywhere rather than 10 inches of insulation in a concentrated spot. The contiguous part is wherever drywall is, insulation should be touching it. If it's not touching (for example, if the insulation is on top of wires and not underneath them), the insulation will do nothing.
Another thing to note is that you want to make sure there's no air gap between the layers of "batts," which are the strips of insulation.
In other words, you want the insulation to be the same depth as the joists -- if you're using batts and not loose-fill (or blown) insulation -- otherwise, there will be an air gap when you add the second perpendicular layer of insulation.
If the depth is lower than the joist, there will be an air gap from the second layer; if the depth is higher than the joist, there will still be an air gap from the joist to the second layer. Only the first layer needs to be the same depth; the second perpendicular layer can be thicker.
And the first layer needs to be as thick as necessary depending on the Energy Star recommended R-value for your geographical location. The R-value is a measurement of how effective a material is in preventing heat loss. The higher the R-value, the better.
Keep in mind, when insulating your attic, you want to make sure you're wearing protective equipment and covering any exposed body parts to avoid breathing in dust and fiberglass or getting it on your skin. Follow these steps.
Clean out the joist bay so the insulation can sit completely flat
Put a batt of insulation in the bay and cut the length so it fits snugly
Try to cut the batt as perfectly as you can, but it's okay if you mess up -- as long as you fill the bay's depth evenly with insulation
Add the second batt layer perpendicular over the joists, so that the wood is also insulated and not just the bay
Energy audits and the Weatherization Assistance Program
These tips can help minimize air leaks and cold spots in your home. But if you want a more in-depth professional opinion before attempting some of these methods, you can get an energy audit done of your home to see how it can be more energy efficient.
Also, the US Department of Energy has a Weatherization Assistance Program at the state and local level if you qualify as low income, are older than 60 or are part of a family with disabilities. You can check with your local utility company for more details.