How to Find Air Leaks With a Thermal Camera

Air leaks and missing insulation quietly drive up energy bills and create uncomfortable drafts. They are hard to find by feel, but a thermal camera makes them obvious. Here is how to use a thermal imaging camera to track down air leaks in a building.

Why Air Leaks Show Up

When indoor and outdoor temperatures differ, air leaking through gaps carries that temperature with it. On a thermal image, cold air pouring in around a window in winter shows as a cool streak, and missing insulation shows as a temperature difference across a wall. The bigger the temperature gap between inside and out, the clearer the leaks.

Set Up for a Good Scan

1. Scan when there is a meaningful temperature difference between inside and outside
2. For a stronger result, slightly pressurize or depressurize the building, which exaggerates leaks
3. Work room by room so you do not miss areas
4. Scan from the interior to find where conditioned air is escaping or outside air is entering

Where to Look

• Around windows and doors for draft patterns
• At wall to ceiling and wall to floor junctions
• Electrical outlets and switch plates on exterior walls
• Attic hatches, recessed lights and penetrations for pipes and wiring
• Across walls for cool or warm patches that reveal missing insulation

Reading the Images

Air leaks often appear as irregular streaks or plumes following the path of moving air, while missing insulation tends to show as broader patches. With practice you learn to tell the two apart. Documenting the images gives a clear before picture for any sealing or insulation work.

Choosing the Right Tool

Energy and building inspection work benefits from a camera with good sensitivity so subtle differences are visible. Brands like FLIR and Extech offer cameras suited to building diagnostics. Browse our thermal imagers to find one for energy audits and inspections.