Air leaks waste energy and money and make your home uncomfortable. They can be easy to fix, though.
Look for cracks and gaps outside – especially where different building materials meet (chimney and siding, foundation and brick) and around outdoor faucets. Also check for daylight peeking through door and window frames.
Visual Inspection
Often, the easiest way to identify air leaks is through a visual inspection. Start by walking around your home, looking for cracks or gaps where different materials meet (like where siding meets a window), or areas of missing or damaged caulk and weatherstripping. Be sure to look inside your crawl spaces and attic, as well. Also pay attention to where ductwork, wires, and plumbing enter the house, as these can also be major sources of air leaks. Daylight peeking through these areas or rattling the frame of a door or window can also indicate a leak.
Some leaks are more difficult to detect, but there are a few ways you can test for them. On a windy day, shut all the doors and windows in your home and turn off exhaust fans and fireplace flues. Then, hold a candle or incense stick up to suspected leak sites and watch how the smoke moves. If it swirls or drifts, you may have a leak.
Another option is to conduct a building depressurization test. Close all the doors and windows in your home and shut off exhaust fans, combustion appliances, and the fireplace flue. Then, light an incense stick and hold it up to suspected leak sites. If the smoke wavers or moves, you have a leak. This method is best used in conjunction with a visual inspection and is only effective on small leaks.
Candle Test
Using the same technique as the hand test, use a candle to feel around common air leak sites. Generally, large air leaks will cause the candle to flicker or go out quickly. Alternatively, you can use your bare hand to feel for a breeze or draft near the seams of doors and windows. A sudden change in temperature can also indicate a leak.
The candle burn test is an important part of a quality assurance program for candle makers. Whether you make candles in jars, tins or votives, each one should be tested before selling. The type of wax, fragrance and wick all impact how a candle burns. Every formula should be burned on at least a few different occasions to ensure it has a normal flame, doesn’t tunnel and produces an appropriate amount of soot.
Begin with a freshly made tester candle that represents your intended product. Place it on a tray big enough to hold all the melted wax if the container cracks or tips over. Clearly mark the jar, wick size and fragrance used to make it easier to compare results later. Keep in mind that some dyes and fragrances may discolor the top of a candle, but this isn’t necessarily a sign that something needs to be corrected. Rather, this is likely due to a variable that could be altered for the future, like the type of wick or container.
Hand Test
Air leaks in homes can cost you money, draining energy from your house and leading to higher utility bills. They can also damage your home’s comfort and increase the time it takes to heat or cool. Air leaks are most common where two parts of your home meet, such as door frames and window frames, floor boards and electrical outlets, walls and ceilings.
Using your hands to feel for unwanted airflow around the edges of doors and windows, light switches, fans and electrical outlets can be a good way to find these leaks. This technique works best in winter, when cold air is blowing and it’s easier to detect drafts.
Other methods of testing for air leaks include shining a flashlight at night over all potential gaps while a partner looks outside and watches for rays of light. These techniques require you to be in the attic or climbing ladders, which can be dangerous. Some air leak detection devices use smoke or ultrasonic waves to pinpoint the location of a leak, but these are expensive and not easy to use on your own.
Using your senses can be an effective and affordable method of finding air leaks in your home. If you smell burning fiberglass, hear a whistling sound or see moving curtains, you likely have an air leak. You can also try a variety of other methods like shining a flashlight or incense, or you can hire a professional air leak detector.
Incense Test
One of the more traditional ways to check for drafts is to use a candle or incense stick. Light the incense and move it around the edges of windows, doors, and other suspected leak sites. Watch to see if the smoke wavers, which indicates a draft.
A variation on this is to use a smoke pen (also known as a smoke pencil), which produces a similar effect without posing the fire hazard of a live flame. This method is also more accurate than a simple visual inspection, as it gives you the exact direction of a leak.
This method is called the incense test, or the “smoke trick,” and it’s best done on a windy day. Turn off your furnace and all exhaust fans that blow air out, including those over stoves, clothes dryers, and bathroom vents. Alternatively, you can set up a box fan in a window facing outward to suck air out of the house (depressurize it). Then, light your incense and pass it over the edge of common leak locations. If the smoke is blown in or sucked out of the room, you’ve found a leak site.
If you’re looking for an even more precise way to find leaks, a professional energy advisor can use something called a blower door, which involves running a large fan in the front of the house to suck all the air out and show where it’s leaking in. However, this requires special equipment and training, so it’s not a DIY project.