Andy Wojtowski

Podcast: Stucco Failures and Home Inspections


In this episode, the gang discusses stucco failure on newer Minnesota homes, as well as failures with stone veneer siding. We also discuss what can be done from a home inspection perspective.

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The following is a transcription from an audio recording. Although the transcription is largely accurate, in some cases it may be slightly incomplete or contain minor inaccuracies due to inaudible passages or transcription errors.

Speaker 1: As you are aware, local home inspectors and contractors have identified widespread issues affecting stucco homes. Stucco specialists say moisture buildup behind the stucco has caused damage to the sheathing, the framing and has compromised the structural integrity of many homes. You can’t always see the potential damage being done. When moisture gets stuck behind the stucco siding, it doesn’t have a way to get out, possibly causing your home to begin rotting from the inside out.

Until the stucco is removed, most homeowners don’t know the extent of the damage that’s been done. Simply repairing or cleaning the stucco doesn’t fix the underlying problems and can actually make them worse. The real issue is how moisture is managed. It usually gets in around windows or where a roof surface meets a wall.

Bill Oelrich: Welcome, everybody. Welcome to Structure Talk, a Structure Tech presentation. Bill Oelrich here, as always, with my co-hosts Tessa Murry and Reuben Saltzman. On today’s show, we’re gonna talk about stucco, “new stucco” and adhered masonry veneer. It’s this fancy new product that you’ll see on a lot of houses that looks like stone but what it is is just a thin veneer and we’re gonna talk about some of the issues that come along with this product. So jumping right into it Reuben, can you take a minute here and just explain when we say “new stucco”, what does that mean?

Reuben Saltzman: I’d say stucco installed from about 1990 on.

Tessa Murry: I would even go a little bit earlier than that, late ’80s, potentially. Houses in the ’80s.

RS: That’s fair. Sure.

BO: So how is new different from old?

RS: It’s a lot of different things that changed and it’s a lot of things that changed at the same time and there’s an excellent article by this guy. He’s kinda known as, I don’t known as “the building science god” or whatever. A lot of codes are based on stuff that he talks about. His name is Joe Lstiburek. I’m gonna put a link to the article on this podcast. Last name is spelled L-S-T-I-B-U-R-E-K, it’s pronounced Lstiburek, starts with an L and he has this one article titled “Stucco Woes: The Perfect Storm” and kinda sums it up really nicely in there but it’s talking about how we made a lot of changes to buildings all at the same time and it’s all of these these going wrong at once. Tess, you just read it before we sat down. You were diligent, right?

TM: Yeah, I was doing a little review on that and like you said, a lot of little things that have changed in the way that we build houses today that have just created this disaster basically, with new stucco. In his article, he doesn’t mention anything about flashing details or roof overhangs or anything like that and that’s something that can also create problems with stucco and… So I was kinda surprised he doesn’t mention that in the article.

RS: I haven’t read it for many years, maybe I need to bone up on that.

TM: Yeah but his highlights in the article were that the properties of building papers have changed so weather-resistant barriers that we use today are much different than what we used to use back then so like a tar paper versus a Tyvek or something like that.

BO: Okay, you guys are talking building stuff. How about a 30,000-foot view? What’s…

TM: The materials are different. Yeah. What goes behind the stucco is different today than what it used to be.

BO: Okay, so what’s the application? Kinda lay it out in 30 seconds.

RS: Sure. Stucco sandwich, you’re gonna have the wall sheathing. OSB, probably. We used to have plywood. It’s gonna be OSB today.

TM: That was another thing in his article too, the change in the wall sheathing material.

RS: Definitely an inferior product. So you’re gonna have the wall sheathing. You have a water-resistant barrier, WRB, that’s gonna be your Tyvek or tar paper, something to keep water from touching the wood, that’s your next layer. Next you’re gonna have metal lath. That’s what the stucco adheres to, it’s just a big screen of metal and then you’re gonna have the stucco. You’re gonna have a scratch coat and then a brown coat and then a final coat. Basically three layers of Portland cement smeared on the side of your house. That’s basically how stucco goes on and if we’re talking about that, we should also talk about stone veneer, as long as we’re talking about the stucco sandwich of your wall.

With stone veneer, it works exactly the same way. You have your sheathing, water-resistant barrier, metal lath, it’s all the same so far and then the last thing is, you have stones that get stuck onto the house and then mortar in between them, maybe, depending on whether it’s dry stack or mortar-filled and it’s the same material, basically. It’s got a different look on the outside but it is stucco and Joe Lstiburek calls it either…

TM: Lumpy stucco.

RS: Yeah.

BO: All right. So how does this material perform differently than say wood, lap siding or vinyl siding or… Kinda give me the lowdown on it.

TM: Well, stucco will absorb moisture, whereas a lot of claddings, like vinyl siding, repel water. They’re a rain screen. So that’s a big difference.

RS: Stucco and stone veneer are basically a big sponge on the side of your house. They’re considered what’s called a reservoir cladding. They’re gonna absorb it. I’ve got a video, I’ll link to the video on this podcast too where I took a cup of water and I pour it up against a house, Shawn’s holding the camera for me, I pour this cup of water up against the house and all the water just gets sucked right into the stone.

RS: Well, not the stones themselves but the mortar joints. Water is gonna go right through this material and when people put this on with the idea that this is a waterproof membrane, that’s where we run into problems ’cause it’s not.

BO: So why would you put a sponge on the outside of your house?

RS: Well, we’ve been doing it forever.

TM: Exactly, yeah. We’ve been doing it for hundreds of years, thousands of years, right? In Joe Lstiburek’s article, he’s talking about Ancient Greeks and all these other cultures that used it. But again, there’s been so many changes to so many different things, right? That’s what’s causing these problems and one of the changes is the actual stucco itself and the properties of it and what materials are in it. It used to be water could travel through it and dry out through it easier and nowadays, it doesn’t breathe like it used to so water can’t dry as easily.

RS: And a really important point here is that we’re not talking about synthetic stucco. In Minnesota, we basically don’t have synthetic stucco. We’ll have it on commercial buildings but residential, it’s all traditional three-coat stucco and you’ll get people who have homes built in the 2000s, the ’90s and they’ll say, “Oh yeah, my house is fine. My house is the real stucco. It’s not that new synthetic stuff that we had all the problems with”.

RS: Oh no, it’s not that stuff we had problems with. It’s the three-coat traditional stucco. That’s been the problematic stuff and I mean Tessa, you’re talking about re-formulating it but it’s still traditional stucco even though it got changed.

TM: Still three coats. It’s just the ingredients are different.

RS: Yes. Yes, exactly. So when someone says, “I’ve got the traditional stuff and… ” and pound the table…


RS: Yep, that’s the stuff we’ve had issues with.

BO: Okay. We’re gonna take a break but Reuben real quick, I know you blogged about this several times. Can you cite where anybody can find that?

07:40 RS: I’m gonna put a link to it right on the podcast page but if you go to Google and you type in “Structure Tech” and you include the word stucco, you’ll find a ton of stuff that I’ve written about it.

BO: Let’s talk about the nuances. It feels like there was this moment in time when it went bad. Why did it seem to go bad all of a sudden?

TM: Well again, a lot of these little things, changes in the building materials we use it, right? So moving from… Older houses they had… What do you wanna call it Reuben? Real wood used for wall sheathing, like planks of wood…

RS: Yeah.

TM: That came from old trees, old-growth lumber so that tree was naturally decay resistant.

RS: Yeah. It was just slices of a tree.

TM: Exactly and when that gets what, it doesn’t rot. Like, what we use today, building composite materials, OSB, it’s pieces of wood that have been glued together. When that stuff gets wet, it does not dry as easily and it rots. That’s one thing and then also two, older houses, they didn’t use insulation and so when walls would get wet you had heat and air flow through those wall cavities and they could dry out much easier. The drying potential of walls today is greatly reduced because the amount of insulation that we have in them. Also we’re using vapor barriers and other things so that if moisture gets in that wall cavity and we’ll talk about how it gets in there in just a second, it can’t dry as easily because it’s full of insulation.

TM: So we’ve made these improvements in terms of making house more energy efficient, making them more comfortable but now we’ve reduced drying potential and increased problems with durability.

RS: Yeah and just to make it really simple, if you wanna make a super durable house, open up all your walls, pull all the insulation out and pull all the insulation out of your attic and you will have an extremely durable house.

TM: It’ll never rot.

RS: Yes.

TM: You’ll never have mold.

RS: Yeah. It’s gonna cost a ton of money to keep it comfortable during our Minnesota winters but that’ll be a very durable home.

TM: Right. So big picture, the houses that were built in 1900 all the way up until probably the ’60s, very minimal installation, things started changing with the energy crisis in the ’70s. People started insulating houses, trying to make them more energy efficient and we also started using more composite building materials. OSB, buffalo board, all those things started kind of in the ’80s and definitely in the ’90s so a lot of changes with materials and the way that we build houses.

BO: How do you think the aesthetics and architects getting into houses… It feels like houses at early on were just basic. They got the job done. They were walls and a roof and now they seem less basic. Do you have any opinions on that? Is there a reason that we’re seeing some failures? Is there…

RS: Oh my goodness, do we have opinions on that? And I think we’ve talked about this in some other podcasts where we’re talking about groundwater management. You go to any of these newer neighborhoods and you see all these roof lines where you think about where are all the water ends up when it’s raining and they’ll concentrate water into small areas and the worst thing is where you take that water and you direct it against another wall in the home.

RS: I’ve got a video where the water is shooting down into all these valleys and then it actually hits the side of a window. I mean, it’s just pounding the heck out of this window.

TM: This was a new construction house, right?

RS: New construction, yes.

TM: You should post that video on the blog.

RS: I will post that too. So it’s all these different things, concentrating water, complicated roof lines…

TM: Lack of flashing, proper flashing details like you were saying before and flashing…

RS: Yeah.

BO: Are you trying to tell me they’re not doing flashing properly? I mean, a new house, they’re still… They don’t have this figured out?

RS: Well, today I think we’ve got it pretty well-dialed in but one of the most critical places for flashing and back up, flashing is a piece of metal typically that keeps water from entering a wall. Or if water has already gotten into the wall, it gives it a place to drain out. One of the most critical areas is where a roof meets a wall, the roof ends at a wall. That’s one of the biggest areas we find water intrusion and what you need right there is something called kick-out flashing. It kicks the water out of the wall. That’s been best practice for a long time now but it wasn’t even required in the state building code here in Minnesota until 2007.

BO: Wow!

RS: No requirement for that so when you say, are they doing it wrong today? Well, you’re required to do it in a new home today and they do a pretty good job of getting every one of them right. Every once in a while, couple times a year, we’ll find where the flashing wasn’t done right but that’s the exception.

BO: Okay.

RS: It’s done pretty darn well today but there was a long period of time where it just wasn’t done or they do it and they do it so it looked good from the ground but it’d be useless.

TM: Well and one thing they’re not required to do today but they should is gutters, right Reuben?

RS: Oh my goodness!

TM: We’ll get into that. We already got into that on different podcasts.

RS: Yeah, yeah.

BO: Okay, so perfection is the key. Your house has to be built perfectly and then it has to never swell or move or change in size and there’s no gaps that ever open up but we all know that’s not the case, especially here in Minnesota. We have a ton of contraction and expansion and movement over the seasons and such. It just feels like this new stucco is up against it from the get-go. Like there’s no chance that it can succeed.

BO: So Reuben, we talked about giving home owners and home buyers some peace of mind. You just bought a house that has new stucco on it.

RS: I did.

BO: So how did you arrive at the decision that that was a good thing?

RS: Well, I was a little worried. I’m always more worried when I’m looking at a newer stucco home but I would never tell somebody don’t buy one of these. My advice is get it tested and I learned most of what I know about stucco homes from Barry Eliason and his company at the time was Private Eye Moisture Testing and we referred him all the time.

RS: Also, at Structure Tech, we’d refer Private Eye Moisture Testing to do tests on stucco homes and at some point, we ended up kinda combining forces and Structure Tech bought Private Eye and so now we at Structure Tech do moisture testing so when I bought this house, I made the purchase contingent upon the home inspection and intrusive moisture testing and I had one of our guys, Antonio go out there and do all the testing on the front wall to make sure that everything was still intact.

RS: And if it’s all intact, my house was built in 2003, it’s all intact now. I’m cool with it. I mean, if it’s gonna fail, it probably would have failed within the first 10 years. That’s kind of the nastiest period of time.

BO: Is that a rule of thumb?

RS: Yeah, it’s a good rule of thumb. I don’t think we see a whole lot of failure that starts happening past that point.

BO: So then once you get beyond that milestone, you’re pretty much good to go?

RS: You’re a lot better. I still wouldn’t even consider buying a home without having intrusive stucco testing and if I were someone buying my home five years from now, I’d wanna get it tested again. I don’t wanna hire my own person to test it.

TM: So you’re saying you wouldn’t do just an infrared scan, Reuben?


RS: Yeah, you’d know better than that. When infrared cameras came onto the market, I thought they were the coolest thing ever and we thought, we’re gonna buy these and we’re gonna start using these instead of doing intrusive moisture testing but turns out all that infrared cameras find is temperatures, they don’t find water. If it’s actually wet and it’s evaporating, it’ll have a very different temperature but if it’s not evaporating, if there’s simply water inside the wall and it’s trapped there, it’s gonna be the exact same temperature as everything else and you’re gonna completely miss a major issue with your camera.

Or if it’s dry at the time and the sheathing is completely gone behind the stucco, I mean there’s nothing there, your infrared camera is not going to pick that up either but when we do intrusive testing and that consists of drilling a couple of holes in the wall, taking a probe to stick it in there, we’re gonna figure that out.

There’s not gonna be any sheathing to test and we’re gonna say “Hey, we’ve got a problem with the wall, you gotta open it up.” So no, no infrared camera tests.

BO: So Tessa, when you’re out doing a home inspection and you’re at a house with new stucco on it, what’s the information given to the clients?

TM: So to the person buying the house I would say, you definitely wanna do an intrusive moisture test on this house and it’s really important to make sure that the sellers sign a purchase agreement that allows that intrusive moisture testing to take place.

BO: So, get somebody out from Private Eye or one of these companies, Structure Tech now because Private Eyes is all us but get somebody out from a reputable company who can do this invasive moisture testing. Okay so I’m just gonna throw it out to you, do we worry about these older houses then? Is there any concern from an inspection standpoint?

RS: I wouldn’t say there’s a bigger concern over older stucco homes and any other type of home and I’m talking wood siding, vinyl, aluminum, whatever it is. I mean, any type of siding can experience water intrusion and have water damage in the walls. It’s specifically the new stucco and the new stone veneer that I’m scared of. Those are the ones that worry me. There’s nothing else that causes concern like that. So old stucco, I treat it just like anything else.

BO: I was just driving around up north last week and we were up near Brainerd and there’s a lot of new cabins, newer cabins, lots of houses that were built in the ’90s and they have this product, this lumpy stucco as you were talking about it, all over or stone that’s just been applied to wood chimney chases. I feel like there’s some real potential for failures going on around the Lake Country.

TM: Well, they wouldn’t be the first. We’ve had a lot of issues with it here in the Twin Cities and all over the country and Canada. Woodbury, here in Minnesota, has an actual report that they released on issues with new stucco houses, right Reuben?

RS: Well, it’s more than just a report…

TM: It’s an opinion.

RS: It’s a position paper where they basically said they don’t feel that stucco is a suitable wall cladding here in Minnesota. That was a very controversial paper when it came out.

BO: That’s the overall finding?

RS: That was their conclusion.

TM: You know what, I just looked at that paper recently and they have updated data on how many houses in Woodbury they surveyed that are new stucco and how many of them have had issues with this water intrusion. It’s something like 58% of them have failed and every year they find more and more and more so that number keeps increasing it from the time that this article was written to now.

RS: Yeah, it’s pretty crazy.

BO: Thanks everybody, that was great information. Here’s the bottom line. You can do your homework and have confidence buying these buildings. All you have to do is work with a reputable company like Structure Tech to go in and do the invasive moisture testing for you and work with a great agent who knows how to navigate these waters. You can have peace of mind buying a house with stucco or stone veneer on the outside of it.

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