Top 5 Dumbest Ways to Build in the South

on the build show today the top five dumbest things you can do when you're building a new house in the south let's get going on today's episode the top five dumb things you can do when you're building a house in the south now bear with me here we're gonna get a little geeky we're gonna talk about some good building science principles and this is really intended for builders remodelers and architects or maybe you're building your own house in the south but if you're in the north or maybe even in Canada stay tuned I think you'll find this interesting so number one what's the dumbest thing you can do vented rubes vented attics you know when we build a house in the South actually let me let me draw this for you I'm a pretty good drawer here's what we've got here we've got a southern house we've got a lot of rock here and typically not much frost line or no frost line so slab on grade or crawlspace then was we build the house we actually drop the roof on top we put the fluffy stuff the insulation right there above the sheetrock and then we ventilate the roof thinking that that's the right thing to do now that is good from a durability standpoint if the roof leaks it's gonna dry out but is this really the right thing to do from an energy or a moisture standpoint let's think about this for a minute in fact let me show you a quick photo here you know here's my buddy's house this is a 1970s house and look what's up in his attic we've got ductwork we've got some old insulation things are not looking so good after about 50 years or so and let's take a look at a new house in the south this is just a one year old completed house again a friend of mine who let me shoot up there and look at this one now what do you see different between those two photos we've got that fluffy stuff going on down here we've got again duct work up there and besides the wood color it's basically the same construction type in between those two photos you don't see a whole lot of differences now is it really making sense for us to build the same way 50 years later let's think about this by ventilating we think that we're gonna reduce the Attic temperature which is going to help the energy efficiency but what's the primary way that we heat up our attics and our roofs the primary method of heat transfer is radiation remember your high school science class there's three forms of radiation we've got conduction that's when I feel your forehead and feel if you're hot that's conduction it's conducting between my fingers we've got convection that's your hairdryer blowing that hot air and drying your hair out and we've got radiation you know Jordan my office just to put a burrito in the microwave a minute ago he's gonna set that timer on there and in a short period of time that burrito is gonna get crazy hot now let's take a look at that burrito that burrito after it's been in the microwave for a very short time got super hot and we're gonna actually have to probably blow on it and cool it a little bit but could I blow on that as the radiation was hitting it and cool it enough that I could actually eat it while the radiation was happening that's akin to trying to ventilate our Roos and cool them down it isn't happening even with radiant barrier decking up there you're gonna reduce that heat intake a little bit but not enough to make a significant difference and that's why houses in the South even with radiant barrier decking are 120 degrees without that it might be a hundred and thirty 140 degrees now that's just heat let's think about moisture for a minute let's go back to the drawing board on this so as the radiation heats the roof and we ventilate that space what's the temperature up in that attic it might be a hundred and thirty degrees and we've got this hot humid air leaking in where's that hot humid air gonna accumulate and it's gonna accumulate potentially on any cold condensing surface that might be some exposed sheetrock if the insulation got blown away that might be the top of our ceiling joists but either way that's a recipe for disaster in fact that's how a lot of mold grows in attics not good number one in the list vented roofs now stay tuned no one's going to come back on the list in a minute here but number two on the list very similar vented crawlspace again let's go to the drawing board here and show you what a vented crawlspace looks like okay so here's our crawlspace here we got the crawlspace walls we get the house built on top of that crawlspace we've got our our floor joist right there and then again we've got some fluffy stuff right there to insulate that floor now we ventilate that we bring in this hot humid air and that air comes into an environment that's coupled to the ground temperature the ground temperature typically around 50 maybe 55 degrees what's it gonna find a cold condensing surface that's how we find a lot of moisture and a lot of mold issues in crawl spaces by ventilating I'm super dumb idea and number three on the list ducts in the Attic or outside of the conditioned space this one's very similar to number one in fact when we talked about vented roofs we saw a lot of photos of ductwork up in attics now why is that in the south in the north we've got basements we're having to dig down in because we've got these frost lines but in the south we've either got crawl spaces or we've got slab on grade just as dumb to have your ducts in your crawl space as in your attic let's think about this for a minute you know this is an old folks home not too far from where I live it's got a flat roof and I always laugh when I go by because the ductwork is on top of the roof so that ductwork is up in an environment that's what a hundred degrees super high humidity I wonder if there's some sweating going on with that but really is that any different than putting our ductwork up in an attic remember this this is the house that's only a year old and now that ductwork instead of being outside it's in the super harsh super hostile environment of this attic that's gonna get to 120 130 degrees pretty crazy let's go back to the drawing board and let's think about this one for a minute okay so here's our attic now from before this is the vented attic and now we're gonna put our ductwork up there what happens with this this ductwork is maybe our six or our eight up in the attic so it's actually much thinner r-value than the rest of the fluffy stuff that's up there that's maybe our 30 or our 40 and now when this duct works up there and it leaks a little bit leaks some cold air into the attic what's happening it's going to depress sure eyes of the house that's there's minus symbols here it's depressurizing the house and when that depressurizes what's it gonna do it's gonna force the house into a vacuum situation which means the house is gonna want to suck in air to make up for the loss to air where is it gonna suck up its gonna come from underneath our bottom plates maybe through our windows and doors and certainly around any holes in our ceiling recessed cans HVAC outlets things like that in fact that's where a lot of the dust comes from your house is from air leaking around your HVAC boots bringing with it some of that dusty insulation and depositing on your coffee table it's also bringing hot and humid air from it from the Attic let's say if that attic was 130 and 70% humidity it's bringing in that super hot air in not only that if your HVAC equipment is up in the attic think about what happens if it turns off for a few minutes let's say the equipment is running the duct works at 60 degrees but the outside attics at 130 it turns off for 10 minutes how long is it gonna take for that are six or that are eight duct to heat up and get super hot and now when the furnace kicks on that's up in the attic it's gonna blow that hot humid air or really just hot air into the house when it first kicks on super stupid now how do we fix these that couple of these can be fixed with a pretty easy solution let's go back to the drawing board I'm gonna take a look at this one okay so here's what we can do we can now go to a condition to attic now it looks simple on paper here all we're gonna basically do is bring bring their fluffy stuff or the insulation up to the roof line now our ducts are in the conditioned space so now when we look at that return air in the center here and the two supplies if it were to leak no big deal it's within the conditioned envelope of the house this is both the thermal and the air sealed envelope of the house is on this outside boundary of the house for the roof now we have to be careful when we make this change there can be some unintended consequences we need to air seal really well we need to make sure that our roof deck doesn't get wet because if it does it's not going to dry like it did in a ventilated roof and we need to be cautious when we change from a crawlspace - an unvented crawlspace but if you get these details right we're gonna add a ton of energy efficiency comfort and durability to our houses it's crazy that we're still building like these houses that were built in the 70s today it'd be like if I went to the car dealership and bought a 1970s car that had a beautiful 2018 body on it but it still had the same guts as a 1970s car that's what our houses are like in the south often we need to build beyond code we need to get beyond these all right number four on the list of the dumb things you can do in the south brick on the outside of a house you know I love brick it's an incredible product it can last nearly forever you can beat it with the Sun there's no maintenance but the problem with brick in the south is what happens behind the brick now let's think about this for a minute let me go back to the drawing board here so here's a brick facade on the house we've got a slab on great situation here we've got a brick ledge the brick is getting stacked on by the mason and the beauty of brick is it's got a built-in air gap behind it but what happens to brick when the rain comes you know the rain droplets are hitting that brick and that brick actually soaks up a ton of moisture let me pause for a second here and actually want to show you a quick video of this rock facade of a house and how much water it actually wall up takes so I shot this a couple years ago actually link to this video below but what I did was I was doing a remodel in the house and I was able to open up the rock facade on the back side pull out the the house wrap that was on there and then I took a hose and I hose down the front and within a few short seconds we were seeing liquid water on the back side of that rock facade now the same is happening on a brick facade just like a rock facade when the water hits out on the front it's both soaking it up and basically it can run right through there it's going to be very very porous so back to the drawing board here as that water soaks up on there that brick is like a big sponge on the outside of the house or a big Heidrich capacitor meaning a ton of water is soaking and then when the rain stops and the Sun comes out what happens the sun's rays are gonna beat on that brick it's gonna want to dry it where's it gonna dry some of that's gonna dry to the front but a lot of that's going to dry to the backside of the brick now remember that one-inch air gap we talked about on the brick that's behind it that's a good thing it's gonna leave a drainage in a dry space but what happens behind the brick oftentimes the mortar is collecting at the bottom and it's preventing that water from getting out both liquid water or steam the other thing that happens often times on brick is builders are not paying attention to the vapor barrier and the weather resistive barrier the WRB in the backside of that we want to make sure that any steam in that cavity from that wet brick as the Sun comes out is not finding a cold condensing surface and because our houses are air-conditioned so much of the time it can easily find a spot to condense and we certainly don't want to find condensation happening on the back of the sheetrock that's a real bad deal especially when we've got that big sponge on the outside of the house so brick I have a love-hate relationship with it I love it because it'll last forever but you got to get the details behind your brick right you got to flash it correctly you got to make sure we don't get any bulk water back there and we have to be cautious about the vapor getting in the house as well number 5 on my list stucco stuck it was similar to brick or stone it's a masonry product that gets applied by the stucco guys on the outside of the house they're gonna trowel it on it ends up being about 3/4 thick you know I love to stuff I love to talk about stucco as like a sidewalk on the outside of the house stucco can hold a lot of moisture and just like brick when the Sun comes out that moisture can get forced to the backside the problem with stucco is it doesn't have the built-in air gap that brick does you know brick with that one-inch air gap has some amount of capacity even if we have some mistakes behind it to drain and dry but stucco way less capacity and I find a ton of problems on our remodel stucco houses here's a quick for instance here's a house it's about 20 years old when I went to do the window replacement job we pulled the stucco around the windows man I found a ton of problems now this particular house the problem wasn't necessarily with a bad house wrap install but that the window is leaking a small amount of water in the corner there was no sill pan and it was leaking behind the stucco and because there was no drainage plane behind that stucco that water had nowhere to go but into the wood framing and because there was really no drying or no drainage that just absolutely got destroyed it was toast 20 years later now how do we do stucco better number one we need to really focus on doing the best job we can on the weather resistant bear that's the waterproofing back there but you also need to do an air gap or a drainage layer behind the stucco there's some great products like our sponsor Dorkin has a delta dry stucco and stone product which will leave an air gap behind the stucco I've used that a lot and that works really well it basically turns your stucco install into more of a brick install so now you've got a drainage and an air drying layer behind the stucco but it's all about getting those details right guys really that's what it comes down to for all five of these if you're if you're doing these wrong make it your goal this year to at least change one of these five things and do them better on your houses because ultimately these are gonna lead to failures on the houses that you build in 10 20 maybe not till 30 years but it is gonna lead to some problems and these houses are not gonna last as long as they should be if you do these details better everything we talked about today guys was derived from a fantastic paper from Joe ste brick called the top ten dumb things to do in the south I'll put a link in the description below but he and his smart team at building science corporation also have some great white papers on solutions how to do an unvented attic or an unvented crawlspace correctly look in the description below for a link to both the paper that this was based on and a couple papers on how to do this correctly I'm also gonna put a couple of links to videos that I've made on how to do some of these things correctly things like ventilating behind your stuck out things like doing your base wall flashing behind brick correctly but either way guys this is some good building science terrain if this is new to you if you've not heard about this stuff before you need to get trained in the tenets of building science this is really important for you as a builder or a model or an architect or even if you're gonna be building that dream house of yours guys thanks for joining me great topic today click that subscribe button below if you're new that way you'll get notified we've got new videos every Tuesday and every Friday we publish a new video on Tuesday it's Reisinger goes rogue and on Friday it's the build show like we talked about today otherwise follow me on Twitter Instagram we'll see you next time on the build show [Music]

Channel: Matt Risinger

Views: 1,287,074

Keywords: Building, Stupid building, Vented roof, unvented attic, crawlspace, brick, stucco, construction errors, building mistakes

Id: Vwos211XlXo

Length: 16min 33sec (993 seconds)

Published: Fri Feb 09 2018