Reuben's Home Inspection Blog

head_left_image

Stucco: Invasive Moisture Testing vs. Infrared Scanning

 

I’ve heard of home inspectors in Minnesota offering infrared scans on stucco homes as an attractive non-invasive alternative to standard invasive moisture testing.  Here at Structure Tech, we recently started offering infrared inspections, but stucco scans are something we will never offer.

Stucco CrackFirst, some info on stucco.Stucco homes in Minnesota built since the late 80′s or so have had a nasty history of catastrophic failures.  These stucco homes are more likely to have moisture instrusion problems than other types of homes, and the damage is usually far more serious. The City of Woodbury has an excellent position paper about Stucco in Residential Construction, which should be required reading for anyone buying a stucco home built during this time period.  In many cases, there are absolutely no visible signs of moisture instrusion.

Invasive Testing

My advice to anyone buying a newer stucco home in Minnesota is to have invasive moisture testing performed, which can be done from the interior or exterior (this blog isn’t going to be a discussion of the two methods, although that will be a great future topic).  Exterior testing is done by drilling holes and  sticking metal probes in to the wall to measure the moisture content of the wood. 

Invasive Stucco Testing
These holes get covered over with matching caulk after the work is done, and there is virtually no evidence that any work was ever done.  Interior testing is done in a similar manner, where holes are made inside the house and the moisture content of the wood is tested.  As long as the person doing the testing is good at it, the results that come from invasive moisture testing on stucco homes are highly reliable.

Infrared Scans on Stucco

IR Image of bad windowHaving a stucco home scanned with an infrared camera as an alternative to invasive moisture testing may sound like a great idea, as there are never any holes left in the walls with this testing method.  The problem is that infrared scans on stucco are unreliable.  Infrared cameras don’t see inside walls; they only show differences in temperature.

For example, the image at right is an infrared image of a window at a stucco home.  You can see a little green at the lower left corner of the window, which means this area is a little bit colder.  This was the worst area of moisture intrusion at the home, and an invasive moisture test found there was no wood to probe here; the wood had rotted away to nothing.

If only an infrared scan had been performed, what would the recommendation have been?  Tear the wall open?  Have an invasive test performed?  This was the only thermal anomoly shown on the entire house, but an invasive moisture test found unacceptable moisture levels in about a dozen other areas throughout the house.

Temperature differences may or may not equate to moisture intrusion.  Conversely, if there are no temperature differences in stucco, should one conclude that there is no moisture in the wall?  Absolutely not.  Infrared cameras are great at finding temperature differences, but not water. Infrared cameras can be used to give clues for places to perform invasive tests at best.

The bottom line is that infrared scans on stucco homes will give unreliable results and should not be considered an alternative to invasive moisture testing.  I’m a firm believer in invasive moisture testing on stucco homes, and I say this as someone with no financial interest in the matter.

 

Reuben Saltzman, Structure Tech Home Inspections

        

Comment balloon 35 commentsReuben Saltzman • February 22 2011 06:43AM
Stucco: Invasive Moisture Testing vs. Infrared Scanning
share
I’ve heard of home inspectors in Minnesota offering infrared scans on stucco homes as an attractive non-invasive alternative to standard invasive moisture testing. Here at Structure Tech, we recently started offering infrared inspections,… more
Thinking of adding more insulation to your attic? Read this first.
share
If you're tired of dealing with ice dams and you've decided to finally get your attic re-insulated, please read this first. You might save yourself a lot of time and money. Over the past two months, a large portion of my… more
How Much Snow Can My Roof Hold?
share
After the recent collapse of the Metrodome roof, the collapse of a hardware store roof in Glenwood, and a recent Super bowl commercial from Allstate, some Minnesota homeowners are starting to wonder if they should be worried about their own roofs… more
Recessed Lights Are Evil
share
I love recessed lights, but even the best ones create a ridiculous amount of heat in attics, which can lead to ice dams Until I started performing infrared inspections in attics, I never quite grasped how much heat recessed lights… more