Reuben's Home Inspection Blog

Stucco Homes

June 19th, 2012 | 8 comments

If you plan to buy a newer stucco home in Minnesota, heads up: stucco homes in Minnesota built since the late 80′s or so have had a nasty history of catastrophic failures.  I decided to write about this after doing a home inspection in Blaine where the entire development was having the stucco torn off all the homes and James Hardie siding was being installed instead.   The average cost per home exceeded $100k.

Stucco CrackNewer 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 no visible signs of moisture instrusion.  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.

Invasive Testing Basics

Exterior testing of stucco is done by drilling holes in the stucco at suspect locations, sticking a moisture probe in to the wall, and measuring the moisture content of the wood or wall sheathing with a special moisture testing device, such as a Delmhorst Moisture Meter.

Invasive Stucco Testing

Interior testing is done by drilling holes in the interior walls, and then sticking a long moisture probe through the wall to the exterior wall sheathing to take a moisture reading.  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.

To gather information for this blog, I spoke with moisture testing experts from three of the larger stucco testing firms in the Twin Cities: Barry Eliason of Private Eye Moisture Testing, Wayne Shellabarger of Acuity Engineers, Inc., and Alan Powell of Certified Moisture Testing.  I asked them about their preferred testing methods, and asked them to explain why.  All three can provide both interior and exterior testing, but they each have their own preferences.

Interior vs. Exterior – Cosmetic Issues

Whether holes are drilled in walls from the exterior or interior, the walls won’t look exactly the same when the work is done.  The person drilling holes in stucco will come equipped with a wide range of sealants to fill the holes when they’re done, and the resulting 1/4″ holes are barely noticeable once filled with with matching caulk.  For interior testing, the holes aren’t as easy to hide or patch.  If holes are drilled in drywall, they’ll obviously need to be patched and painted over again.

Cosmetically, exterior testing is certainly preferred, as you really need to walk around the exterior of the house and carefully look for the test locations; they’re not obvious.  The photos below should help to illustrate just how inconspicuous the holes from exterior testing are.  Click on any of the photos for a larger version.

Holes from stucco testing2

Holes from stucco testing

Holes from stucco testing3

Interior vs. Exterior – Holes In The Stucco

One concern with drilling holes in stucco is that this will compromise the drainage plane behind the wall, and the caulking used to fill the holes won’t get far enough in to the wall to seal the drainage plane again.

Wayne Shellabarger, who is opposed to exterior testing, said that he has found holes in the drainage planes that were never properly sealed up after invasive testing was performed.  I asked him if there was water damage caused by the breaks in these drainage planes; the answer was no.

Alan Powell said that while the holes they drill in stucco are 1/4″ holes, they don’t drill through the drainage plane behind the stucco.  The only thing that penetrates the drainage plane behind the stucco are the pin probes on the moisture testing device, which leaves 1/8″ holes.  When you think about all of the holes that get created in the drainage plane with staples and whatever else, the holes made by the pin probes will be quite insignificant.

After over a decade of invasive testing and having tested thousands of homes, none of the companies that perform exterior testing have had a single reported problem with this testing method.

Interior vs. Exterior – Accessibility

The biggest problem that Barry Eliason expressed about interior testing is that there are oftentimes interior wall surfaces that make testing impossible in some locations.  There are several places where holes can’t be drilled, such as through bath tubs, shower walls, tiled walls, and cabinets just to name a few.

Difficult locations for interior moisture testing

Alan Powell also expressed concerns about being able to test in the proper places on interior walls; windows usually leak in the corners, and to properly test the right areas, the wall sheathing directly behind the walls studs is the most critical area to test.  This area can’t be accessed from the interior walls.

Alternatives to Invasive Testing

Infrared Scans on Stucco

IR Image of bad windowSome companies in Minnesota offer infrared scans on stucco houses as an attractive non-invasive alternative to traditional moisture testing.  These companies claim to have had good luck using infrared cameras to find moisture behind stucco walls, but I say they don’t know what they’re missing.

All three testing companies that I interviewed said the same thing about infrared inspections on stucco homes: they’re unreliable.  Each company shared the exact same experience with me.  They were excited when infrared cameras came onto the market, they purchased $10k – $15k infrared cameras, they went through extensive training on the use of IR cameras, and then they began using IR cameras on houses before performing invasive testing.

After comparing the results over and over again, they all said that IR cameras are a completely unreliable way of finding moisture behind stucco.  Wayne Shellabarger’s web site says they use infrared cameras as a starting point before performing invasive testing, but he told me they no longer even offer that service because it has proven to be a waste of time.

I have yet to hear from a single home inspector, anywhere in the country, who has performed infrared scans on houses, compared those results to an invasive moisture test performed at the same time, and can still claim that infrared scans on stucco houses are reliable.  Infrared cameras can only identify differences in temperature; they don’t identify the presence of moisture.  We offer infrared inspections, but not as a way to find moisture in stucco buildings.

The bottom line is that infrared scans on stucco buildings 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.  My company doesn’t perform invasive moisture testing on stucco homes; we refer this work out to the people who specialize in it.

Non-Invasive Moisture Meters (aka – surface scanners)

Stucco homes in Minnesota have metal lath, making surface scanners completely useless.

Conclusion

Here in Minnesota, performing an invasive test on stucco is the only way to know what’s happening behind the stucco.  Problems can’t be positively identified using visual inspections, surface scanners, or infrared cameras.  Visual inspections will often provide clues that a problem exists, and so will infrared scans, but that’s all they can do.  Many times, stucco homes will have serious problems without any visual or infrared evidence.

As for the interior vs. exterior testing debate, they both have their pros and cons.  If you’re buying a newer stucco home in Minnesota, have an invasive moisture test performed.  You’ll need to hire a company that specializes in this, such as one of the companies that I listed at the beginning of this blog.

Oh, and of course, you’ll need to get special permission from the seller to do this.  Drilling holes in walls is invasive; home inspections aren’t.

Reuben Saltzman, Structure Tech Home Inspections

        

Invasive Moisture Testing on Stucco, Revisited

March 1st, 2011 | No comments

I recently wrote a blog about invasive testing vs infrared scanning on stucco homes, and concluded that invasive moisture testing is the only reliable test method for stucco homes.  I received quite a bit of feedback on ActiveRain, and even had another home inspector in San Diego, Russel Ray, write a follow-up post titled Invasive “testing”?  Are you kidding?, wherein he opines that invasive moisture testing is outdated.

Today I’m going to explain why invasive moisture testing is not outdated, as it’s the only reliable option in Minnesota, and I’m also going to discuss the differences between interior and exterior moisture testing.  But not in that order.

To gather information about this blog, I spoke with moisture testing experts from four of the larger stucco testing firms in the Twin Cities: Barry Eliason of Private Eye Home Inspections & Moisture Testing, Wayne Shellabarger of Acuity Engineers, Inc., Alan Powell of Certified Moisture Testing, and one other expert who wished to remain anonymous.  I asked them about their preferred testing methods, and asked them to explain why.  All four can provide both interior and exterior testing.

Interior vs. Exterior – The Basics

Exterior testing of stucco is done by drilling holes in the stucco at suspect locations, sticking a moisture probe in to the wall, and measuring the moisture content of the wood or wall sheathing with a special moisture testing device, such as a Delmhorst Moisture Meter.  Interior testing is done by drilling holes in the interior walls, and then sticking a long moisture probe through the wall to the exterior wall sheathing to take a moisture reading.  These are both reliable testing methods.

Interior vs. Exterior – Cosmetic Issues

Whether holes are drilled in walls from the exterior or interior, the walls won’t look exactly the same when the work is done.  I’ve inspected many stucco homes that have had invasive moisture testing done, and in every case the holes were quite inconspicuous.  The person drilling holes in stucco will come equipped with a wide range of sealants to fill the holes when they’re done, and the resulting 1/4″ holes are barely noticeable once filled with with matching caulk.  For interior testing, the holes aren’t as easy to hide or patch.  If holes are drilled in drywall, they’ll obviously need to be patched and painted over again.

Cosmetically, exterior testing is certainly preferred, as you really need to walk around the exterior of the house and carefully look for the test locations; they’re not obvious.  The photos below should help to illustrate just how inconspicuous the holes from exterior testing are.

Holes from stucco testing2

Holes from stucco testing

Holes from stucco testing3

 

Interior vs. Exterior – Holes In The Stucco

One concern with drilling holes in stucco is that this will compromise the drainage plane behind the wall, and the caulking used to fill the holes won’t get far enough in to the wall to seal the drainage plane again.

Wayne Shellabarger, who is opposed to exterior testing, said that he has found holes in the drainage planes that were never properly sealed up after invasive testing was performed.  I asked him if there was water damage caused by the breaks in these drainage planes; the answer was no, but he was also quick to mention that in the cases he has seen, the holes were only a year or two old.

Alan Powell said that while the holes they drill in stucco are 1/4″ holes, they don’t drill through the drainage plane behind the stucco.  The only thing that penetrates the drainage plane behind the stucco are the pin probes on the moisture testing device, which leaves 1/8″ holes.  When you think about all of the holes that get created in the drainage plane with staples and whatever else, the holes made by the pin probes will be quite insignificant.

After over a decade of invasive testing and having tested thousands of homes, none of the companies that perform exterior testing have had a single reported problem with this testing method.

Interior vs. Exterior – Accessibility

The biggest problem that Barry Eliason expressed about interior testing is that there are oftentimes interior wall surfaces that make testing impossible in some locations.  There are several places where holes can’t be drilled, such as through bath tubs, shower walls, tiled walls, and cabinets just to name a few.

Difficult locations for interior moisture testing

Difficult locations for interior moisture testing

Alan Powell also expressed concerns about being able to test in the proper places on interior walls; windows usually leak in the corners, and to properly test the right areas, the wall sheathing directly behind the walls studs is the most critical area to test.  This area can’t be accessed from the interior walls.

On the other hand, Wayne Shellabarger said that if a home has moisture problems, there will still be enough accessible areas for him to find problems, even if he can’t find every one.

Infrared, revisited

Some home inspectors say they’ve had good luck using infrared cameras to find moisture behind stucco walls, but I say they don’t know what they’re missing.  I think everyone can agree that invasive moisture testing is accurate; if a tester drills holes and sticks moisture probes in the wall, they’ll be able to locate moisture if it’s there.  To know if an infrared camera can reliably detect moisture in walls, one would need to scan a house with an infrared camera and then compare those results to an invasive moisture test.  If an infrared camera could reliably find wet areas behind stucco, it would be useful.

I have yet to hear from a single home inspector, anywhere in the country, who has performed infrared scans on houses, compared those results to an invasive moisture test performed at the same time, and can still claim that infrared scans on stucco houses are reliable.

All four testing companies that I interviewed said the same thing about infrared inspections on stucco homes: they’re unreliable.  Each company shared the exact same experience with me.  They were excited when infrared cameras came on to the market, they purchased infrared cameras, they went through extensive training on the use of IR cameras, and then they began using IR cameras on houses before performing invasive testing.  They all say that IR cameras are a completely unreliable way of finding moisture behind stucco.  Wayne Shellabarger’s web site says they use infrared cameras as a starting point before performing invasive testing, but he told me they no longer even offer that service because it has proven to be a waste of time.

Non-Invasive Moisture Meters (aka – surface scanners)

Russell Ray mentioned in his blog that he has had a 100% success rate testing for moisture on stucco homes in California using a surface scanner, such as a Tramex Moisture Encounter Plus.  This device is a fairly inexpensive non-invasive moisture detection device that, according to the manufacturer, can be used on “drywall, wood, plaster, brick, ceramic, porcelain tiles, resilient flooring, laminates, asphalt composition shingles and most building materials.”  Stucco isn’t listed.

I called the manufacturer to ask about using this device on stucco (I spoke with Penny).  She said that if the stucco has metal lath, it won’t work.  This is the same with all non-invasive surface scanners.  If the scanner is used from the interior, it also won’t work, because it won’t read nearly deep enough in to the wall to reach the exterior wall sheathing, which is the part that needs to be tested.

When Russell or anyone else has a 100% success rate using a surface scanner on stucco, that means they’re not using it on the same type of stucco that we have Minnesota.   Stucco homes in Minnesota have metal lath.  Surface scanners will have a 0% success rate on this material.  To echo Russell’s point, regional differences are huge.

Conclusion

Here in Minnesota, performing an invasive test on stucco is the only way to know what’s happening behind the stucco on a newer stucco home.  Problems can’t be positively identified using visual inspections, surface scanners, or infrared cameras.  Visual inspections will often provide clues that a problem exists, and so will infrared scans, but that’s all they can do.  Many times, stucco homes will have serious problems without any visual or infrared evidence.

As for the interior vs. exterior testing debate, they both have their pros and cons.  If you’re buying a newer stucco home in Minnesota, have an invasive moisture test performed.  You’ll need to hire a company that specializes in this, such as one of the companies that I listed at the beginning of this blog.

Oh, and of course, you’ll need to get special permission from the seller to do this.  Drilling holes in walls is invasive; home inspections aren’t.

Reuben Saltzman, Structure Tech Home Inspections – Email – Infrared Home Inspections

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Stucco: Invasive Testing vs IR Scanning

February 22nd, 2011 | 2 comments

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.  One such company that offers this service is Certified Moisture Testing, who we have recommended many times over the years.

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 – Email – Infrared Home Inspections

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