Usually a low level of moisture is fine, but leaks or heavy condensation can cause serious problems. A thermal imaging camera cannot “see” moisture in walls, but it can detect subtle temperature differences and patterns that reveal the existence of water.

Looking above the leak in the ceiling is a good start, but you'll also want to check near common areas where water may gather in the roof, such as corners, where roof joints meet or near roof features, like skylights, valleys and chimneys. Use Light to Your Advantage.

The FLIR E8 XT is one of the most accurate and reliable thermal cameras on the market, perfect for professional home inspectors. This camera offers exceptional thermal sensitivity and can detect moisture damage, electrical problems, and structural defects.

Turn off any appliances that use combustion fuel (think: gas-burning water heaters and furnaces). Turn on all the exhaust fans in your kitchen and bathroom. Burn incense or light the candle, then hold the flame or smoke near doors, windows, and any other places where air might be leaking in or out. Watch.