Home Inspection Pricing Guidelines

Thermal (infra-Red) Imaging

There are many firms that tout the new fancy Infra-Red Camera (imager) and the many training seminars they have gone to and seem to think they are the best thing since sliced bread.

Thermal Imagers are indeed a very useful tool but you really need to fully understand what the imager sees to understand what it can do, and more importantly what it can't do.  There are times and conditions under which the imager is blind, and there are also conditions which will "Fool" the imager into showing artifacts that are not really there.  Additionally, some things that look really really weird, are just fine. Again you need to know what the imager is seeing, and what you SHOULD be seeing.  Classroom theory is a nice thing, but Inspections by Bob believes that experience and an understanding of what is going on is more important for the home inspector to be able to "read" the images the thermal imager provides.

Yes, Inspections by Bob has a Thermal Imager, and we don't use it very much, but when we do use it, it provides a view that no other tool could.  Also please note that our STANDARD contract specifically states that we cannot address those items which we cannot SEE and a thermal imager allows us to see something, but we still cannot see through walls, we can see symptoms that MAY be an indicator of something inside the wall, but the ONLY way to see inside the wall for sure is to cut a hole...and we don't do that.

Thermal Imagers see radiant Heat, and can measure the amount of heat that they are seeing very very precisely... routinely to less than 1/10th of 1 Deg Celsius.

 

There are 4 Cups in this picture, one full of cold water, one partially full of warm water, one full of warm water and one empty. Can you tell which cup is which?  Notice that the EMPTY cup blends into the image rather well.  It is much easier to see something that is WARM.

If there is no temperature difference (the empty cup) there is nothing to see.  The larger the difference, the easier it is to see.

Also note that this image is a COMBINATION of Thermal and Visible.  In a pure thermal image, the empty cup would be invisible.

(this is what happens when the inside and outside are the same termperature)

 

That said, a thermal imager can be configured to see very very small differences in temperature. The image to the right is of the floor where I was just walking (yes, in just my socks) . The imager is seeing where my feet warmed the floor temporarily, and yes these images fade very fast.  Technology like this is used by the military and police to track people and vehicles by their thermal impact on their surroundings using even more sensitive imagers...

How does this help the home buyer as thermal imaging is not part of a normal inspection?  If I suspect a problem I may take out the imager to confirm something that I suspect, or that other indicators point to,  Recently in a newly constructed house they had to open up a wall to reconnect the Heat-Pump refrigerant lines. The wall "felt" cold as did the room. Lets start with what a "Normal" wall looks like.

 

You can see the wall studs, barely, but in the majority of the wall there is not much difference between the insulated section and the stud section.  Where two wall sections meet there is a bit more difference, but not a lot.  I would probably rate this as "Acceptable".

 

However, looking at the wall NEXT TO this one, we see something different.

 

The large sections show what APPEARS to be voids in the insulation where they likely compressed the insulation to put the refrigerant lines in (The Heat pump compressors were directly behind this wall section) and then never "re-fluffed" the insulation.  This is what we THINK is behind the wall, but without cutting a hole in the wall we can't be sure.  What I wrote was that I THOUGHT there was an abnormality in the wall that made sections much colder than the rest of the wall.  

 

 

 

I also saw the condition below where an outside corner was MUCH colder that the surrounding wall sections. I suspected that there was an air leak at the sill plate and that I was seeing the effects of a draft. You can see how the (suspected) draft starts in the corner and extends out following the slight gaps caused by edge stapling the insulation. Moisture can cause a similar image but in this case the moisture meter said that the wall in the corner had the same moisture content as the rest of the wall.

 

Note: We started with a standard inspection, something was suspected, our standard observations (hands, eyes) lead us to believe there was a possible hidden issue. The thermal imager allowed us to "See" what we had felt with our hands.  We cannot SAY for certain what the issue is that is causing these images without cutting holes as we still can't see through walls.

Using a thermal imager is not practical on every inspection as it takes a lot of time to setup properly.  And if the outside is the same temperature as inside, the camera will be blind. (remember the empty foam cup?) I use the thermal imager as a tool, just like my outlet tester, moisture meter, thermometer, flammable gas detector and the myriad of other things in my car.

 

Comming Soon : Other things that the Thermal Imager allows you to "see"