How to Find Air Leaks in Your House: 4 Professional Methods to Save on Energy Bills

Identifying and sealing air leaks in your home is one of the most effective ways to enhance comfort and reduce heating and cooling costs. According to the Environmental Protection Agency (EPA), air sealing and proper insulation can save homeowners an average of 15% on their energy bills. This guide outlines four proven methods, from a simple visual inspection to a professional home energy audit, to help you locate drafts and improve your home's efficiency.

What Are the Most Common Signs of Air Leaks?

Before conducting tests, knowing where to look is half the battle. A thorough visual inspection is a free, DIY-friendly first step. Focus on areas where different building materials meet or where penetrations exist. Common sources of air infiltration include:

• Electrical outlets and switch plates on exterior walls.
• Door and window frames, checking for cracked or peeling caulk.
• Weather stripping around doors for signs of wear.
• Baseboards where walls meet floors.
• Vents for dryers and bathroom fans.
• Recessed light fixtures in ceilings below attics.

A simple way to check is to feel for drafts on a windy day or hold a thin piece of tissue paper; if it flutters, you’ve likely found a leak.

When Should You Consider a Professional Blower Door Test?

For the most accurate assessment, professionals use a blower door test. This diagnostic tool involves mounting a powerful fan into an exterior doorframe. The fan depressurizes the home, making outside air rush in through all unsealed cracks and gaps. This allows an energy assessor to precisely locate even the smallest leaks. There are two primary types:

• Calibrated Blower Doors: Measure the exact amount of air leakage, providing a quantitative assessment of your home's airtightness.
• Uncalibrated Blower Doors: Identify the location of leaks but do not measure the severity.

Based on our experience assessment, a professional blower door test typically costs between $300 and $500. Some local utility companies offer discounts or free assessments to promote energy efficiency.

Can You Perform a DIY Building Pressurization Test?

If a professional test isn't an immediate option, a building pressurization test is a viable DIY alternative. This method helps verify suspicions from your visual inspection. To conduct this test safely:

1. Turn off all combustion appliances like gas furnaces and water heaters.
2. Close all windows, exterior doors, and fireplace flues.
3. Turn on all exhaust fans that blow air outside (e.g., bathroom fans, range hood, dryer).
4. Carefully pass an incense stick or a thin plume of smoke near suspected leak areas. If the smoke stream is drawn into or blown away from the gap, you have identified an air leak.

Safety Tip: Always keep an open flame away from flammable materials. As a safer alternative, consider using a handheld draft detector.

What is Included in a Comprehensive Home Energy Audit?

A home energy audit provides a whole-house evaluation of energy performance, which includes air leak detection as a key component. A certified auditor will use tools like blower doors, infrared cameras (to visualize temperature differences caused by drafts), and moisture meters. The final report typically prioritizes energy upgrades, which can be especially valuable if you are planning to add insulation or replace windows. This holistic approach ensures you address the most significant inefficiencies first for the best return on investment.

How to Fix the Air Leaks You Find

Once identified, sealing leaks is straightforward with the right materials:

• Caulk: Ideal for sealing stationary cracks and gaps less than ¼-inch wide, such as around window frames and baseboards.
• Weatherstripping: Used to seal components that move, like doors and operable windows.
• Spray Foam Insulation: Best for larger gaps around pipes, wiring, and vents. Use low-expansion foam for windows and doors to avoid warping frames.
• Door Sweeps: An easy install to block drafts at the bottom of exterior doors.

For most minor sealing projects, DIY is a practical approach. However, for significant leaks in attics, basements, or crawl spaces, hiring a professional is recommended for both safety and long-term effectiveness.

Finding and fixing air leaks is a manageable project that directly contributes to lower utility bills and a more comfortable living environment throughout the year.