Stucco - Is Rot inevitable? A Lesson In Building Science

on the build show today we're talking stucco I'm gonna show you two old houses one that worked perfectly for the last eighty years and one that's an abject failure let's get going okay so we're talking stucco today and I want to show you two old houses that I've remodeled in the past and show you how those stucco houses worked one of them worked fine for many years and one of them was a massive failure now one of the things that I love about doing remodels is I get to learn things I love this quote from Albert Einstein learning and remodeling go hand-in-hand and those things have made me a better new construction builder so first let's look at this house right here this is a pretty famous house here in Austin Texas just had its 80th birthday or so this house pretty pretty modern construction even though it's 80 years old no overhangs some really interesting architecture going on kind of an art deco house but interestingly enough doesn't look all that different from some real modern brand new construction houses this is traditional three-quarter inch stucco no overhangs really to speak up on this house you can see that that wall goes all the way up and then transitions to a flat roof here's the back of the house and as I walked around the house of the very first time I took these photos and I was trying to note on the outside what might be some problems to see on the inside because we got there a little early for this meeting with his client and some of the things we noticed were things like this on the outside we saw a lot of decay at the windows it had these steel windows that were original the house or 80 years old hadn't been well-maintained in the last ten or fifteen maybe twenty years that had been basically vacant so we saw a lot of rust at the windows but other than that not a whole lot of kind of visible damage the stucco was in relatively good shape for being 80 years old now here's the inside of the house when I showed up to interview for this project the inside demo had already been done so they'd already taken down a lot of the plaster that was on the inside of the house and we to see the bones or the structure and here's how the house is built if you look at the foreground there what you're seeing on the horizontal is the outside sheathing for the house so this house had some type of 1 by 6 1 by 8 shiplap sheathing true pine and then the studs it was a 2 by 4 framed house and then another lay of shiplap sheathing on the inside and this is not chipping Joanna shiplap this is real-deal shiplap here and even shiplap on the ceilings as well so truly a solid wood structure you also notice there was no insulation in any of these bays the house was totally uninsulated I love this shot too you can kind of see this big living room section on the house it had hardwood floors but then everything else you're seeing in the photo is all pine ok now let's take a closer look at one of the windows now on this picture you can see here that those steel windows were rusted out pretty good that they really hadn't been maintained in a long time or painted in a long time but look at that - before sill underneath that window you're seeing a little bit of black staining especially around where the nails were you can see those those two nail holes right there you can see some of those black stains that's where water had probably gotten through the window and had stained that bottom sill but what's absent there's no rot there's really no mold to speak of as well in this house solid wood house that window leaked the solid 2x4 is that were able to absorb that water and there was no insulation in there so there was probably a fair amount of air flow and certainly there was plenty of heat flow through this building as well a little closer look at that again you can see that window probably was taking on a lot of moisture we had a lot of rusts shown on those steel windows but the 2x4 is fantastic shape this old 80 year old stucco building absorbed a lot of water every time it rained it had no overhangs that had no umbrella as I like to call overhangs in the house to shed the water that cladding that stucco was absorbing the water but the structure had a lot of ability to absorb that water as well this image I recreated but I basically stole this for my friend dr. John Straub at rth building science company I've seen him give this demonstration before so thank you dr. Straub for a lot me to use this but basically think about that house as that picture on the right that wood structure as water came in the form of rain water or leaks or even a plumbing leak let's say it started filling that pitcher that house had the ability to absorb a lot of water a lot of you know just a ton of solid wood in that house and how would that house dry will wood dry from air flow there was probably a fair amount of leakage in this house this was certainly built long before codes dictated that we have an airtight envelope and so it was able to dry over time and that's where that water is leaking out of that pitcher but look at that weight the counterweight on the left-hand side of the scale here the house had a giant counterweight the geeky term for that is hydric buffer capacity this solid wood 2x4 is the solid wood sheathing they have a lot of ability to soak up moisture in fact I've heard another famous building scientist dr. Steve Brooks say that houses of this vintage might be able to soak up a hundred or two hundred three hundred pounds of water before they reached their capacity because think about that house is a big sponge and stucco on the outside is a leaky cladding water will get through it it's kind of like a sidewalk on the house but it's also gonna absorb a lot and hold that water up against the house okay we're going to come back to this image in a minute but remember this one as we get to another house now let's fast-forward to another new house and this is actually not a house this is actually a restaurant and here's an image after the remodel but I'm gonna show you some images prior to this remodel similar building and are in kind of general architectural style no disrespect to the architects watching this I'm certainly not a trained architect but what I'm seeing here is you know no overhangs a big stucco square box maybe an overhang over the front door but other than that that stucco is getting soaked every time it rains now this is post remodel I don't have an image of this building before but these images were taken at a location not far from me here in Austin where I saw this remodel happening I love seeing scaffolding remodels and from a distance you can already tell hey what's going on there that plywood looks like it's had some weather on it now this is a stucco building it was built I think in the early 2000s or so so not even a 20-year old building pretty new construction techniques but as I got closer to looking at this building I couldn't believe what I what I was seeing just massive amounts of rot and failure now what's going on a two-year old building with stucco that was in great shape 20-year old building was Tucker that's in terrible shape we're gonna we're gonna show you in a minute this image I think really captures a ton of what's going on here this is at the base of the of the house here this is again 2x4 construction real plywood on the outside which you generally think of as a good thing but this whole section here was just so rotted through that as the demo contractor was pulling that stucco off and you can see it just to the left of that vent pipe there there's there some of that original stuck I was he was pulling it off the sheathing was absolutely rotted it was just garbage at this point now let's pull back and see what we see in this area now this is this is just a few feet back from where I took the last picture look at that gray pipe you know what that gray pipe is that's a sprinkler head now I'm in Austin Texas we have about 30-some inches of annual rainfall not nearly as much as my friends in the Pacific Northwest but what we have here that's a problem for our buildings is we have irrigation and my guess is that sprinkler pipe was probably wetting the building in the middle of the night maybe three or four days a week absolutely soaking that traditional three coat stucco and we're gonna see why in a minute but it was basically overwhelming the weather barrier in this house now you can start to get a feel for it on this photo on the right-hand side just above that pipe you can see that some of that black paper there this house was built with very traditional stucco techniques this is on the back of the bill you can see the plywood on the left then you're seeing two layers of some asphalt impregnated tar paper not exactly sure brand or or type this is probably something like two layers of number 15 asphalt and pregnant it's our paper and then traditional three coats stucco on top of that and what happened on this building was it got overwhelmed it was getting overwhelmed because where there was leaks the building at the ceiling or pardon me at the roof line leaking through the parapet cap it had leaks around some of the windows and doors and it had overwhelming amounts of water at sprinkler heads now here's the parapet cap on this building and as I climbed up and checked that out just massive amounts of rot at the top of the building where that water was falling down from the sky and landing and soaking it it was just in terrible shape now what's the deal both these buildings are similar we had no overhangs we had some leaks clearly in both buildings they both had traditional three coat stucco I wasn't able to show you but the the first house the bone house had two layers of asphalt and pregnant guitar paper and then it had the lath the scratch and the brown coat are part of me in the final coat so it had traditional three coat stucco but what was different here the building on the left is the as the bone house that we showed you eight years later still look fantastic with it stucco finish the building on the right this is not the same one as we saw cuz that was a plywood house but this is pretty typical of new construction in fact that's a house I'd built quite a few years ago what are you seeing there a lot of manmade materials OSB and plywood OSB in plywood have much much less capacity to absorb before a failure happens I use OSB on some of my houses not every time but detractors from OSB like to call it vertical mulch if OSB gets wet and continually wetted on a new building without airflow and without heat flow through the assembly it's going to turn into vertical mulch it's going to disintegrate on you and that means you're gonna have some massive failures so the building on the left lots of drying potential lots of heat flow the building on the right any new construction job not a lot of drawing potential not a lot of airflow even the people that say houses need to breathe there's not enough breathing in a standard code build a house to dry out that Assembly when it gets wet and you can't build a house without insulation so there's gonna be plenty of heat flow or pardon me and an old house there's plenty of heat flow but in a new house there is not heat flow to dry out those assemblies if they get wet so now let's go back to that same analogy from dr. Straub new construction is more like this photo here we've got a very small amount of capacity on that on that cup there even just some drops of water and maybe even a little bit of drying it's gonna tip the balances because we've got a much smaller counterweight in these newer houses we don't have the ability to dry and to drain and to to heat through those buildings so what are the lessons from from these two houses one house 80 years old looked amazing one house 20 years old terrible condition absolute failure well the first thing we need to learn is that stucco leaks stuck it was a leaky cladding there's no amount of paint on the outside or caulking that's gonna keep the moisture from getting through the stucco especially as you have a more exposed building new construction modern architecture no overhangs or even that much more water that it's going to absorb the other big takeaway here is that houses today are sensitive even a small amount of leakage is gonna tip the balance and is gonna kill the house I think the third thing that we need to learn from this is that we can't rely on old methods of stucco when we're building to today's standards when we build to today's standards with with newer codes and with insulation we're not going to be able to use those old methods we need to go to newer methods I love this quote from David Nicastro if it can't dry it's gonna die let me take a minute and let's talk about another couple things here now we only mention houses with no overhangs but what happens if you have some overhang or maybe you have a flat roof but you have a little bit of projection on the roof I love this slide I took this from one of dr. Straub's presentations as well if you have a light rain that's there on the left and you've got an overhang with a more traditional pitched roof that's the upper-left image you see there look how the wall doesn't even get wet the roof even with a little one foot overhang is not getting wet on the other hand with a flat roof without that wind foil of the pitch of the roof a little bit of an overhang but a flat roof means that we're gonna get wet very tall onto the wall and that's what happens also with no overhangs with those modern buildings okay now look at the second image we've got a little heavier rain a one millimeter drop and we've got a little bit of wind now now the second image down there we're nearly getting wet to the soffit the second image on the bottom look at that thing it's it's getting water almost all the way up to the soffit area not good and on the pitched roof still we're not getting the wall wet only we when we have a deluge with some wind are we getting wet on the house with the overhang which means that on most rainstorms we're not getting super wet whereas the house with an overhang but a flat roof whether it's a light rain or whether it's a heavy rain a deluge that building is getting wet and so we need to take special care with those buildings especially the no overhanging buildings this came from building Science corporation Joe dr. Steve brick and his colleagues this is I believe from a Canadian study of houses and look at the houses that have no overhang and how much problems were found in those houses on this Canadian study versus the houses with big overhangs 24 inches very very few problems compared to the houses with no overhangs all right guys I'm gonna close with this quote here from dr. Steve Rick but stay tuned for the next build show I'm gonna go into a few different assemblies kind of a good better best on what will work if you're doing stucco I think you're gonna like this presentation but think about what we talked about today and if you've got any comment from houses you've remodeled I'd love for you to comment below so that I can hear from you on this guy's follow me on Twitter Instagram hit that subscribe button new content every Tuesday and Friday otherwise I'll see you next time on the build show [Music] you

Channel: Matt Risinger

Views: 58,006

Keywords: the build show, stucco, the build show with matt risinger, stucco failures, applying stucco, stucco remodel, remodeling, construction videos, remodeling videos, matt risinger, jordan smith, building austin texas, building builders, austin construction, remodel failure, remodel, stucco build

Id: kKBe9XVDMmw

Length: 16min 10sec (970 seconds)

Published: Tue Oct 02 2018