Thermal Imaging on a Home Inspection
Thermal imaging cameras can be a helpful diagnostic tool when the conditions are right, however, thermal imaging commonly produces false readings which can send clients down the long path of hiring experts to discover the cause of an abnormal reading. The camera may be helpful in detecting roof defects, moisture, missing insulation and electrical abnormalities, but not always. In the dry climate of the Phoenix area, moisture evidence is short lived. Also, the “Best Practices” for performing a residential infrared inspection includes:
- A temperature differential (Delta-T) of at least 18 degrees F from interior to exterior for several hours prior to the inspection. Humidity, wind speed and direction, sun location, recent precipitation all may affect the results from an infrared inspection (having the correct climate conditions is rarely possible during a home inspection).
- To check for evidence of roof leaks, the infrared inspection should be done about two hours after sunset. After sunset is when the air temperature is cooling but the temperature of the roofing system remains warm. This will allow for the required temperature differential (the home inspection is not conducted after sunset).
- To conduct an accurate electrical thermal inspection, the circuits should be under load for several hours prior to the evaluation (it is not practical to have each circuit loaded for an extended period prior to the inspection).
- To conduct a reliable interior infrared inspection, items hung on the walls and placed near the walls need to be removed for several hours prior to the evaluation (it is unlikely that the seller will provide this condition).
A valid question is, why do you want a thermal imaging inspection and are you willing to pay the added cost for a properly conducted infrared inspection? Is there something at the property that raised a red flag and caused the need for an infrared inspection? Most buyers elect for a standard inspection by a licensed inspector as a first step to screen for defects during the purchase process. During the inspection, important areas of the property will be evaluated including: the attic, roof surfaces and inside electrical panels with deadfront cover removed. We look in the attic for signs of moisture intrusion, hidden damage and missing insulation. We access the roof surface to discover evidence of covering failures and flashing damage. At the interior inspection we are looking for moisture evidence at ceilings, walls and floors. An infrared inspection does not replace a thorough home inspection performed by a qualified inspector.
Quality thermal imaging cameras and basic training (Level 1 thermographer) costs approximately $7,000 to $10,000 with additional annual renewal and calibration costs. A proper scan of a house would take 1 to 2 hours in addition to the home inspection and would nearly double the total inspection cost. Some home inspectors today use thermal imaging as a form of marketing to get you to choose them. They often don’t spend enough time, have inferior equipment, inadequate training and no equipment calibration. The public is being duped. Can an average home inspector with a thermal imager find a defect with the device? Yes, but the chance of missing defects or producing false positives is equally high. We suggest that if the home inspector finds evidence of a problem, during a standard home inspection, that an expert further investigate with proper diagnostic tools that might include a thermal imager.