Crawl Spaces : Good vs Bad

on the build show today we're gonna take a deep dive into crawlspace is the good the bad the ugly and how to build them better now if you're building basements to stay tuned I've got some good things for you as well let's get going okay guys coming to you from my studio space today where I'm gonna use some photos and some videos to show you some examples of some terrible crawl spaces why we want to build them better and how to build them better so let's get going first of all crawl spaces this is what we're referring to right here this is a picture of a crawlspace vents which means with this vent right here we probably have a space underneath the house where we can crawl into sometimes you refer to these as a pier and beam foundation as well where you've got the house on wood above some piers but it's this telltale sign right there of the vents that you're gonna see now here's a guy who's about to climb into one usually there's some amount of crawl space meaning you can actually get underneath the house but it's typically a very tight space now we'll tell you that crawl space is our code legal and code compliant but there are also 99% of the time terrible and very dumb I'm not a fan of the typical crawl space construction that you see out there happening all over the US and here's what they look like in fact I'm I'm sorry to say I built a lot of these when I worked in Portland Oregon here's a photo of a crawl space I think this is off of Green Building advisor calm you've got some kind of black poly down on the ground a lot of wet stuff happening probably some moisture intrusion insulation has fallen out and gotten wet spotty down there here's an older one that looks like someone tried to seal it up but crawl spaces on typical American houses they're terrible you do not want to crawl into one I've been to a lot of crawl spaces and they are nasty places with some terrible air quality usually there's some mold growing somewhere because of moisture down there it's not a great place and then you couple that by adding some ductwork into the space and man when you see ducts down there you think oh my air for my house is going through that space there's gonna be some and the Ducks so most likely I'm sucking some air up from that crawlspace this is a terrible way to build we don't want to do standard vented crawl spaces not a good way to go what do we want to do we'll think about this and the north all the northern Builders and Canadians that are watching this video go you guys are crazy for building crawl spaces why not just build a basement there's my buddy mark for my fixative life looks like he's installing some rocks over here and this is what a standard basement looks like why wouldn't we treat our crawl spaces like a basement or like a short basement let's see if we can find another good image or two of a basement here's one right here look at this we've got some rocks all bats it looks like and in this basement what else do you see here's some ductwork right above here and that ductwork now is running through a conditioned space and a space that doesn't have moisture and mold issues it doesn't have venting in from the outside much much smarter we've talked in the past while we don't want our vents up in our hot humid attics the same is true we don't want our ducts into our nasty venting crawl spaces when those ducts down in the crawl space leak air they're gonna put the house into a negative situation and the house is going on wanna suck up air from the outside and most likely it's gonna suck up air through that crawl space and how do we build a curl space that's going to work better let me walk you through a couple here I'm actually going to show you a couple stills and some short videos from videos I've made look in the link in the description you'll see a bunch of these other videos if you want to go deeper but here's a crawlspace I built a couple years ago and one thing you'll notice on this outside wall is there's no venting this is gonna be what's called a conditioned crawl space no venting from the outside and in fact what I'm building here is a short basement now where I'm standing in this video I'm standing on top of this yellow vapor barrier this happens to be stego wrap and we're gonna actually going to pour a concrete slab on top of that and then this house has a perimeter stem wall sometimes pier and beam houses will have perimeter piers meaning concrete piers and then they'll have a skirt board of stucco or stone maybe to encapsulate that but I much prefer to do a concrete stem law on the outside then I'll do concrete piers on the inside now if we fast forward a little bit in this video you'll see that we actually poured a basement slab down there there's the guys actually pouring that slab and now we really do have a short basement just like we were building a house in the north and once that's in place then we can actually frame on top of that and here's me later on in construction now see we've poured a stem wall and on top of the stem wall is a recess in there that is going to accept our floor joists or floor trusses in this case and now we have a short one you know it'd be tougher to crawl on this one but with that concrete slab I actually left this client with a creeper you know mechanic's creeper so you could actually creep around in that crawlspace do whatever you need to and again it's within the thermal envelope of the house it's within the condition crawlspace okay now here's an older video of mine this one still applies that in fact this is about 10 years old so if you want to see what and that looked like in 2010 here's a spring some closed cell foam into again a condition crawlspace now closed cell foam is a great choice for a crawlspace because it's not moisture sensitive it won't absorb any water and it's also a vapor barrier so we don't need to worry about vapor drive either in either direction really from the inside or the outside so if you're looking now starts a little shaky this is my flip video from 2010 but you can see on that perimeter stem wall we've we've sprayed actually closed cell foam around the entire perimeter the other beauty of closed cell foam is it's actually going to air seal us really well so where these I Joy's come in and sit either on top of or in a recess on that stem wall we're able to air seal that space really really well and you really only need if you're in the South typically two inches of closed cell foam that's going to give you an R 14 sorry for the shakiness here this is long before I had a any kind of production value all right now let's fast-forward a little bit and I want to show you a friend of mine and how he builds crawl spaces in another part of the country this is actually addison homes based out of South Carolina I think they're in Greenville and this is a presentation that Todd the own president of the company gave and if you don't have the kind of budgets that I work with to do really top-of-the-line crawlspace like I just showed you here's another one that's a little bit more affordable but also very very good from a building science perspective so where he is he's using concrete block to build the foundation again he's got a perimeter solid wall out of concrete block and then here's his peers that are gonna support beams you know typically wood beams and then joists that will sit on top of that and then if you look on the outside here he's done some waterproofing just as if this was a full eight or ten foot deep concrete foundation whether you're building a crawlspace or a standard foundation you need to do your waterproofing correct to make sure that space is going to be dry so he's got his waterproofing on the outside and then on top of his waterproofing it's always best practice to run a drainage board this happens to be by the guys at Delta and this is a little hard to tell from this photo but this is a dimpled mat that has a fabric facer on the side so against the waterproofing is a dimpled mat kind of like an egg crate that's going to go against the foundation wall and then on top of that dimpled mat is this grey fabric right here and that's a filter fabric so that when we backfill against here we're not gonna fill up that space we're always gonna have at least a one-inch air gap in front that way any water that migrates through the soil is gonna hit that air gap and drop all the way down and then he's got a perimeter drain around the outside here the guys that Polly wall make an arroyo drain that's a really really good one I've done some videos on before okay so now let's take a look at what his crawlspace looks like in fact I love how he makes this he has his carpenters build this little ladder that goes from my closet and he's got a little hatch you also noticed the hatch here is not insulated and it doesn't need to be air sealed because when you get down into the space this is what you're looking at look at this this is gorgeous he's got a white vapor barrier down there this looks like it might be clean spaces it's been taped on all the seams it's been cocked and adhered to the pier so we've got a nice tight vapor barrier any moisture migrating up from that not gonna make it pass there and then in the outside walls he's not using clothes I'll spray film he's using a sheet insulation this is a rigid insulation looks like this happens to be dowtherm acts and he's adhering that probably with some concrete nails to the outside perimeter now and he's got an airtight insulated encapsulated crawlspace this is really impressive this is from a presentation that Todd did at IBS with me now a couple options for for vapor barriers these guys at clean space make it really nice when I've used this one before you could also get the one by stego those guys make some really good products I like stager because they've got some excellent tapes that would hear really well to concrete in your concrete piers and look at this guy down here this is a beautiful crawlspace we've got the ducting in there we've got this stego wrap my guess is the insulation is behind here in this case but we now have a very hospitable place there's no concerns about bugs about rodents about rats down there in effect we've got a short basement now what happens if you can't afford all that or what happens if you're watching this in your retrofitting you're not building new like I am or doing a whole house remodel like I typically am one way that you might consider doing a retrofit is to do this this is closed cell foam sprayed in the crawlspace up on the bottom decking now typical insulation we don't want to use batt insulation or the standard kind of fiberglass insulation in your crawl spaces because when we use those we're gonna be prone to a lot of issues we can get air flow through there really easily it's really easy for condensation to happen down there and there's moisture all spaces especially in the south but this can be an option if you have to stay with a vented crawlspace this is one to two inches of closed cell foam sprayed right underneath the decking so we've got a perfect air seal you can see it's sprayed onto the eye joist as well this happens to be from my Friday video or is talking about a houston flood victim that's been rebuilding check out the video haven't seen it but this is a good way to to retrofit if you need to and your not building new and can't do these practices lastly if at the end of the day you're building new and you're worried about your crawlspace am I gonna do it right I'm not sure I my builder has the ability to do that or I'm worried about doing that myself my last recommendation is to avoid them if you're not able to do a condition crawlspace and really do these details right the next best thing is to go with a concrete slab this time if you're building in southern climates you don't have to worry about frost line and so a concrete slab is a great choice here's one that I poured here in Austin and think about this now when we build a house on top of this there's no issues with air under there there's no water issues there's no critter issues we can make a really tight seal between the framing and the concrete on the outer edges and now we don't have those issues from that crawlspace we also don't have wood underfoot and the give that that wood gives you and we don't have insulation down there too so it's not the best choice in a colder climate but if you're in the south and you can't do your crawlspace right you might consider slab on grade as well guys thanks for joining me for a deep dive on crawlspace is the good the bad and certainly there's a lot of ugly out there do it right spend the time and money do the research check out my links below I'm gonna put a bunch of links in there for you both from videos that I've made I'm gonna send you a couple links from some white papers from building science comm there's a lot of good reading on the interwebs about how to build a condition small crawlspace correctly but I want to encourage you to do that if you've been building them vented for years stop doing that and if you've got a vented crawlspace currently consider doing a rehab project on that and turning that into a condition crawlspace or at a minimum using that closed cell foam underneath there to lock everything in and seal it up so that your house isn't exchanging air with that crawlspace anymore follow us on Twitter Instagram all the walls we'll see you next time on the build show [Music]

Channel: Matt Risinger

Views: 424,549

Rating: 4.8870378 out of 5

Keywords: build, build show, build with matt risinger

Id: 5n4K170f56I

Length: 13min 29sec (809 seconds)

Published: Fri Mar 02 2018