Thursday, June 21, 2007

Infrared Thermal Imaging, What's it Really Good For?

I have noticed quite a bit of blogging relating to using infrared thermal imaging cameras for home inspections. Some of these blogs are nothing more than an ad for how the home inspection company is ahead of the technological curve. But what really is the the truth about using thermal imaging as a home inspection tool.

The first and most important thing to understand about infrared cameras is they do not see through objects. That's x-ray folks. Infrared is thermal or temperature readings of the surface of an object. Now infrared cameras are extremely temperature sensitive. Because of this sensitivity they can display pictures in temperature gradients. The image may appear to have a great degree, no pun intended, of temperature differential, when in fact there is little temperature range.

Notice the the image to the right. The temperature range is about 11 degrees. What are you looking at in this picture?

Missing wall insulation. The dark areas in the center of this infrared thermal image show clearly where the insulation company failed to fill the stud bay. The bays on the immediate left and right are only partially filled. Look closely at the right hand wall and the ceiling. Can you see the stud lines?

Now this is a great example of a good use of infrared thermal imaging. Heat and energy loss. Makes sense right, temperature sensitive camera-heat and cooling deficiencies.

What it is not really great for is a general inspection tool or a mold locater. Why? Because there must be ideal infrared conditions present to find problems such as a water incursion. Simply taking the camera out at the time of the home inspection and scanning the home will not necessarily reveal anything.

Which brings up another important aspect of the thermographers job, to know when and how to use the camera in order to locate an existing problem. Most infrared building diagnostic companies use spray racks to systematically wet the building in order to find a leak. They use the infrared camera along with a moisture meter to track back to the water source.

If your lucky during the day of the home inspection or very recently it has rained. Now you have a very good chance of locating a leak or source of a moisture problem. Of course rain is not the only source of water leaks in a building. A plumbing leak is just as common. The thing with a leaky pipe is a good home inspector will likely find it during the course of his inspection.

Having rain during the home inspection when using infrared is not the only needed thermal condition. Temperature differential is also very important. Lets say the inside of the home is 70 degrees and out side it is 58. The inside has been 70 for several hours. This is what I call a temperature equilibrium. The surfaces in the home have been at the same temperature for many hours with the outside temperature relatively close to the inside. Because of this the walls will appear to the infrared camera with very little detail.

As you can see infrared thermal imaging is far from an exact science. It is crucial that the person operating the camera is trained in the use of the camera, thermal dynamic principles, and interpreting infrared images. Owning an infrared camera and offering infrared as an ancillary home inspection service does not assure a skilled operator.

I use infrared primarily as an energy auditing and heat and cooling loss tool in CT where I perform home inspections. I have found infrared to be a fantastic device in this application. I have almost never used it to locate water leaks and when I have was disappointed in the results.

Okay, so what is infrared thermal imaging really good for? Everything I discussed here and much more. So long as it used within the parameters of its' limitations by a skilled operator.

James Quarello
JRV Home Inspection Services, LLC


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