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Moisture Testing Stucco

Water damageNewer stucco homes in Minnesota have had a nasty history of failure. Specifically, homes built since the 1980s on up to today. While any type of exterior wall cladding can experience water intrusion, the failures that happen with stucco are far more expensive and usually far more extensive.

The city of Woodbury has an excellent position paper on Stucco houses that should be required reading material for anyone buying a stucco home in Minnesota. This paper was first released in 2003, and has been updated several times, with the latest and final update from 2011. Click here to read it: Stucco in New Residential Construction.

So Woodbury had problems with stucco. Other cities are fine, right? Heck no; this really had nothing to do with Woodbury; they were just the only city that was bold enough to talk about it. They came under heavy fire for putting out a position paper that questioned the viability of stucco, which supposedly lowered the value of existing stucco homes, which made up a significant portion of their housing stock.

The Solution

If you’re buying a newer stucco home or you already own one, there are a few ways to determine (or attempt to determine) if there is a moisture problem.

Cut it open. Cutting right into the stucco and pulling it off will definitely tell you if you have a problem, but of course this is extremely expensive and unsightly. If there isn’t a problem, you’re left with a bunch of nasty cut marks at best. The image below shows what stucco looks like after an exploratory hole has been cut and the hole patched up again.

Stucco Patch

Video Scope / Borescope inspections. This involves sticking a small camera into wall cavities to examine the condition of the walls. Because exterior walls are insulated, this is extremely difficult to do and the results are nearly useless. This method also won’t detect elevated moisture levels, meaning that the wood may look good but still be saturated. We don’t recommend this.


Scan it with an infrared camera. This seemed like an attractive option when IR cameras first started becoming affordable, but thermal imaging has proven to be an inconclusive method for detecting water problems with stucco homes. We are not aware of any reputable companies offering this service in Minnesota. The images below show a suspicious are where the stucco is cooler, but this doesn’t mean that water has entered the wall sheathing.

Infrared image of potential stucco leak

Exterior probe testing. This involves drilling 3/16” holes in stucco at strategic locations, and then inserting a moisture probe into the wall to measure the moisture content. This is an accurate and reliable method for determining if there are water problems. We’ve been doing this type of testing since the late ‘90s, and we can say with certainty that there is no better method. Check out the video clip below showing Wayne Rademacher conducting a moisture test on a stucco home.

Interior probe testing. This is similar to exterior probe testing, however, this type of testing is much more limited because of interior finishes that cannot be damaged and stored personal items. This is a service we offer, but our preference is to conduct exterior probe testing because it’s more thorough. The most critical areas to be tested cannot be accessed from the interior. The images below show a couple of examples of areas that can’t be tested with interior probe testing; holes don’t get drilled in tile, wood paneling, or similar decorative finishes.

Inaccessible locations for interior testing