How to Find Air Leaks in Your House

Whether you live in a hot, dry climate like Phoenix or a cold, snowy one like Boston, air leaks can quickly drive up your heating and cooling costs. Your HVAC system works hard to keep you comfortable year-round, but if conditioned air is escaping through gaps and cracks, you’re essentially paying to heat or cool the outdoors. 

Here’s how to find air leaks in your home and fix them, so you can stay comfortable and save money.

How to find air leaks in your house

There are four main methods that are used to detect air leaks in a house:

• Visual inspections
• Blower door tests
• Building pressurization tests
• Home energy audits

Below, we’ll go into detail about how each of these processes work and how they can help you find air leaks throughout your home.

1. Detect an air leak with a visual inspection of your home

The simplest way to find air leaks is to simply take a look around. A thorough visual inspection can help you find areas throughout your home that might be allowing air to escape. The best thing about this method of detecting leaks is that it’s totally free, and homeowners can do their own inspection if they know where to look. Common sources of air leaks include:

Common sources of air leaks

• Electrical outlets
• Switch plates
• Door and window frames
• Baseboards
• Weather stripping around doors
• Dryer vents
• Recessed lights

2. Call in the pros to conduct a blower door test

When it comes to air leak detection, the blower door test is probably the most accurate and widely used method by professional energy assessors. Simply put, the blower door test works by pulling air out of the house, lowering the pressure inside. Because of the pressure difference this creates, the air on the outside flows into the house through any unsealed gaps. 

This process can also work in reverse, with the blower door increasing the pressure in the house and leaks being detected by analyzing where the air escapes from.

There are two types:

• Calibrated blower doors: measure exactly how much air is escaping.
• Uncalibrated blower doors: show you where leaks are, but not how severe they are.

Cost tip: Expect to pay $300–$500 for a professional test. Some utility companies offer them for free or at a discount.

3. Try a building pressurization test for DIY air leak detection

Though not quite as comprehensive or successful as the blower door test, the building pressurization test is another great way for homeowners to detect areas where air is leaking. After conducting a visual assessment of your home and identifying potential leaks, this test can let you know if you’re losing efficiency.

To conduct a pressurization test:

1. Shut off all combustion appliances (gas furnaces, water heaters)
2. Close all windows and doors
3. Turn on all exhaust fans that blow outside (drying machine, bathroom fans, stove vents)
4. Light an incense stick and hold it near potential leaks; if the smoke is blown into the room or sucked out, then there’s an air leakage

Safety tip: Keep incense away from flammable surfaces, or use a handheld draft detector instead.

4. Get a complete evaluation of your house with a home energy audit

A home energy audit assesses your home’s energy use while finding any inefficiencies, including air leaks. Auditors often use blower doors, infrared cameras, and moisture meters to get a full picture of your home’s energy performance. This can be especially helpful if you’re planning insulation upgrades or want a prioritized list of fixes.

Why is it important to find air leaks in your home?

Detecting air leaks throughout your home is an important step in maximizing its efficiency and saving energy. According to a study from the Environmental Protection Agency (EPA), homeowners can save an average of 15% on their heating and cooling costs by adding proper insulation. Finding and addressing air leaks is not only key to maintaining a comfortable home, but also a smart investment that can save you money down the line.

How to fix air leaks

Once you’ve found the leaks in your home, seal them with the right materials for each location:

• Caulk small cracks and gaps around trim, baseboards, and window frames.
• Weather strip exterior doors, attic hatches, and movable windows.
• Install door sweeps to block drafts at the bottom of doors.
• Use spray foam for larger gaps around pipes and vents.
• Insulate attic access points and recessed lighting fixtures (if safe for contact with insulation).

DIY vs. pro tip: Most small sealing projects are DIY-friendly, but for major leaks in attics, basements, or crawl spaces, consider hiring a pro for safety and effectiveness.

Final word on detecting air leaks in your house

No one wants to be uncomfortable in their own home, especially when the source is costing you hard-earned dollars and is entirely avoidable. If you notice a draft in your house or think your energy bill is higher than it should be, now might be the time to take a look around and identify any possible air leaks.