Thermal Imaging Facts

A lot of inspectors out there are offering thermal imaging as part of their services.  What the experts are saying, however is that the quality of camera most of these home inspectors are using are not up to standards in the industry.


  • Thermographic imaging is a science; in fact experienced and certified thermographers will tell you it is not always an exact science although they do their best.  Why?  Because the conditions during a thermographic inspection need to be as precise and consistent as possible; and if they aren’t, the inspection will be postponed until such time the ideal conditions exist.
  • Atmospheric conditions.  There must be at least a 20 degree F differential between the indoor and outdoor temperature for a period of several hours in order to conduct an accurate test.  The exterior surfaces must be free of moisture (dew in most cases).  Wind speeds should be less than 8 mph.  Let’s be honest; there are many days in Central Texas during the fall, winter and spring when these conditions simply will not exist on any given day for a scheduled inspection.
  • Sunlight; it tends to complicate the thermal inspection process especially during daytime heating of the exterior.  Exterior walls should cool at least three hours before an inspection; eight hours if the exterior walls contain brick or stone.  In other words; the best time to do a thermographic inspection is during non-daylight hours; when a typical home inspection should not be performed.  And if there are moisture leaks, the best time to detect them are during the hours when the structure is cooled.  Wet areas will appear much cooler than dry areas.
  • Other considerations.  A complete thermographic inspection should include the exterior and interior so that a comparison can be done and conclusions drawn.  A blower fan should be used to increase the interior ambient pressure gradient to exaggerate leaks in the thermal envelope for accurate detection with the camera.  If the home is occupied, furniture, furnishings, wall hangings, etc. should be removed from walls or set away from walls for a period of 12 hours.  Ask the inspector the name, make and model they are using.  You can make a quick internet search to find out what they paid for it.  If it’s < $5000, it’s not up to the standard certified thermographers use in the industry.

I’m all for getting a leg up on the competition and making a buck.  It’s good for business and the consumer will always benefit from that.  However, home inspectors who tout thermal imaging as part of the inspection may be using it as a marketing gimmick or even a crutch.  A thermal imaging camera can be another tool in the tool bag that may on occasion detect an issue during a home inspection, but all it's going to reveal is a temperature differential; and that could be anything.  An experienced and competent home inspector can and will detect what a camera would see if he is doing his job.  Make sure you get in writing that the thermal scans offer a significantly better inspection than one without the thermal imaging camera.  In fact, I'd ask for a 100% guarantee.  

Buyer should beware of what you may be led to believe.  The average quality home inspection duration without specialized equipment is two to three hours.  If the inspector is spending time with the infrared camera during those two or three hours, he may be giving less attention to some of the home’s other systems that need it.  

The decision to hire a home inspector should never be based on a thermal imaging camera.

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