Attics/Roofs - Dumb vs. Smart - How to Build Correctly

on today's video guys I want to do a little bit of a rebuttal from my Friday video top five dumb ways to build in the south and on today's video we're gonna review how it's been done and how we can do it better not just goals for energy efficiency and ways to make a terrible design better but really I'm gonna give you some systems and specifically I'm gonna give you three systems for a really well-built house with an excellent conditioned attic space that's we're going to focus on today so let's go over the computer here and let me show you a few images from some houses that I've built and that I've been a part of over the years so first off how's it been in Texas and what does it look like for many southern houses this is an example of a very typical 1970s construction house down here in Texas slab on grade construction we've got a single-story with a hip roof on top and here's what it looks like inside that roof this is an attic that was built you know almost 50 years ago now fluffy stuff on the bottom some ductwork up there but as I was investigating this one for a remodel I found a lot of areas like this we've got missing insulation we've got a sheetrock from the ceiling visible below my guess is that is that this house was very uncomfortable to live in with this type of insulation and ducting up in the uncondition a very hot attic space now fast forward another couple decades here's a house that I ultimately did a remodel on this is pretty typical Texas Tuscan style for some reason Texas loves our Italian style houses and and so we built a lot of these over the years now this house only built about 15 years ago look at this attic really really similar to the 1970s attic even though this was built around 2000 or right around that decade and look at this attic now we've got again ducts up in the super hot vented attic space we've got recessed cans poking through the insulation you can see in the back here we've got some venting up there really not much had changed over those 20 years now let's fast-forward to a new home it may actually go back to the Internet here here's some images of just I just kind of googled Texas new home and it's interesting how all these images look very very similar but here's a house that a friend of mine built production builder but this is really an attic that's very common whether it's production or a custom builder and look at that attic just really similar to those other addicts that I showed you not too long ago ducts up there may be some newer looking fluffy stuff now we've got a radiant barrier decks now they've worked they haven't leaked and if they did leak they probably dried well because they were ventilated but they were not energy efficient and probably not very comfortable as well and the indoor air quality is not the best so now let's switch gears let me show you three smart ways to build an easy way to go from a conditioned or partly from a ventilated uncondition attic to a conditioned atticus spray foam this is used by builders all across the country but especially down here in the South where we've got slab on Greater crawlspaces we don't have a lot of room for our mechanicals in the basement it's a really easy way to take a standard house either retrofit or new construction and we can take that spray foam in sprayer right here to the roof line look at this house this is one that I built probably eight or nine years ago and all we had to do is spray that open-cell foam right up on the underside of the deck and now we've cathedral eyes our attic now all the mechanical systems are within that air conditioned space so think about this HVAC system now if we've got some leakage around these ducts here or any of these boots it's going to leak into the open envelope it'd be as if this ducting was in our living room and it leaked no big deal now this attic is not particularly meant to be conditioned we don't have vents and registers up here but we've got enough leakage typically on a system that we've got what was considered a semi conditioned attic now when I built if I were to build the same assembly today I'd actually talked to my mechanical designer about putting a specific supply vent into that attic so we could make sure that that attic air was semi conditioned and really was dehumidifier that's really important especially when we're building in the hot humid South so we'd actually probably put a small supply up here this is the return side but a small supply in this area over here where we're gonna get you know maybe 20 CFM or 30 CFM of supply air into this space again that's really for dehumidification purposes and now this attic up here is gonna be maybe three or four degrees hotter than the rest of the house compare that with those other houses I showed you from the 70s from the 90s and from today that are built with addicts at a hundred and thirty degrees one hundred and fifty degrees maybe without a radiant barrier decking crazy hot and when the furnace kicks on in those unconditioned attics its depressurizing the house and so as a result the house is trying to suck in air to make up for that and that's that's a double whammy for energy inefficiency the ducts up in the superhot space they're only like an r6 or r8 we've got lots of radiation from the Sun beating down heating up that attic and we've got that depressurization every time the furnace kicks on from leaky ductwork I'm that attic doing it attic like this makes a whole lot of sense however there are some details that you need to be cautious of for instance look at this photo this is a gas furnace that's up in a conditioned attic space and look how we get the venting for that furnace we really need to stop using standard 80% gas units or even 75% efficient and go to the 90-plus furnaces these are going to use PVC venting because they've captured so much of the heat from that gas flame that the exhaust there is very cool so now we can use a PVC vent in to bring the air into the sealed combustion burner and then we can vent out on PVC this through the roof here it's a little hidden behind this spring that's kind of dampering the unit from vibration and vibrating the floor below but this is what's called a concentric vent it's a PVC pipe that's gonna stick through the the roof and then we could put a roof check on that or even better we can put it through the walls now how do we get to that roof we need to pay attention to some of the details for instance here's one that I did a few years ago here's your rafters coming down and normally if this was going to be an attic where we've got fluffy stuff here and we're insulating on top of the the lid or the drywall ceiling we're gonna have bird blocks in here for airflow but in this case we've got these solid block there's a to buy in here and then we've got some OSB and we've solid block that now where you can see the light coming through we need to seal those up and you can seal that with either open or closed cell spray foam but if I'm gonna do open cell on it I actually like to come in and do a bit of a pre foam ahead of time let me scroll down here and I'll show you what that looks like so in this case I've sent one of my carpenters into the attic and we've used closed-cell canned foam all the foam that you buy this in a can is closed-cell foam and we've gone through in any light that we're seeing we've gone ahead and use closed cell foam on there for maximum durability for stopping of air flow and vapor flow through there and then this attic ultimately got sprayed like this to be an open cell I won't go into all the differences now but if you're in the South you can use open cell successfully if you're in the north you need to be cautious about that because you've got vapor that can go through open cell and so you want a typically in the North use closed cell foam if you're doing this type of attic okay so next what if you don't like spray foam or what if you're worried about spray foam in your envelope a couple things I want to recommend number one I'm going to put a link to this in the description below but green building advisors Martin holiday super smart building scientists he has a great blog post on how to create this conditioned attic with some great points on here I don't want to go through all this but there's Martin right there and I'm gonna put a link in the description of this you really want to read this before you do a conditioned attic and just go in and spray foam it but oh I know one more thing I want to show you apologize this is a video I made a couple years ago on changing codes and moving to 2014 and 2015 codes I want to show you what that looked like with a truss roof and here's one that I did it looks like around 2014 that had a truss roof and spray foam and look at that that spray foam is adhering to that roof deck and works really really well with traditional trusses so even if you're not doing a rafter house like that other one with hand-cut rafters you can do this as well but here's the one I want to show you if you're not a fan of spray foam or you don't want to spray foam in your attic you can use other insulation methods owns Corning's come out with this just two or three years ago they call this their pro pink condition - attic system this is actually just their display from the International Builder show kind of a cool system it looks like this they basically net the Attic kind of like you're gonna do a blown in bid system and you can see it gets stapled to the side of the rafters or the trusses and then this right here is a netting that expands out and forms kind of a balloon in there that they can fill with loose Ville now you've got to be cautious when you do this because you want to make sure there's no air flow into the attic so you want to pre foam this and I'm sure if you use an Owens Corning contractor they've been trained in that but there's a in my mind a little bit more of a kind of risk when doing this so you really got to pay attention to details but if you don't like spray foam this is a really good way to do it another way that you can do it if you want to again keep very cost effective is do a method like Alison bails talks about in this blog post I'm gonna figure familiar with him but he runs energy Vanguard comm a great building science blog again I'll link to this post he did a couple years ago but he's an energy or part of me an HVAC designer and he has a great blog post on plenum trusses I've heard of lots of builders doing this even production builders who are very cost sensitive and so this could be a way to do it bringing those ducts into the Kinsmen space if you're worried about cost so right here traditional truss and here's a plenum truss it basically makes a boxed out space and now instead of having this big mass of ductwork up in the attic check out this this photo right here may be a little hard to see but he's got the ducts inside that Bay that's being created with that truss and now all this ductwork look how small this is he can be in the center you can design your house around this and now he's probably got a ceiling register or pardon me a wall register right here for these bedrooms everything's nice and compact it's been designed correctly fits within that space and then you can put traditional fluffy stuff above that and this is an airtight drywall so now you don't have any airflow between there and the attic this would be a great way to do a conditioned attic on a budget bringing all those ducts down into that space in the last way that I want to show you let me go back to my to my keynote presentation from from over here is I want to I want to take a minute to talk to you about perfect wall well if you've seen my videos on this if you're new to my channel I'll put a playlist down below but this is a house that I built a couple years ago with this system that's incredible but I'm gonna give you just a brief on it but basically the system is one where we utilize all exterior insulation no interior insulation so here's the house that was designed by rouser design that we built a couple years ago and you can see the house looks like a big Monopoly piece no overhangs framed at this point and the reason why is we want to run our waterproofing which is also our air membrane continuous from the foundation all the way to the ridge and then back down to the other side again the house is wrapped totally and completely with this membrane the membrane goes on as a peel-and-stick product this is actually a primer that gets applied to the shear wall prior to installing it and then you're gonna roll that membrane on and we actually rolled it vertically installed our windows and then use the detail sealant so this house was 100% waterproof and airtight and also vapor tight at that outside layer now here's what the framing looked on the inside when we were at that stage we she'd that with one by sixes on the inside so it would look like an old house because remember we're not going to put inside insulation on this house and as a result we ended up not using sheetrock on the house as well but I'll come back to that in a minute looks let's take a look at what the outside look like once it had been wrapped with that membrane then we took a couple layers of exterior insulation and blanketed the house with that it'd be kind of like if it was cold outside would you rather put a sweater on or an insulated jacket would you rather stuff that insulation in between your ribs this puts a giant sweater on the outside of the house look at this roofline here we've got two four inch layers pardon me two three inch layers of foam on the outside that's Paulie ISO so it's outside foam not inside foam and when we were done we completely wrapped the house I think we had four inches on the walls six inches in the roof 100% continuous and then we put a rain screen batten on top of that this is a basically a 1 by 4 that screwed through all that thick exterior insulation into the studs we also do that on the roof line so we could put the metal roof and still have some airflow up there here's kind of a detail of what that metal roof looks like so now we have a conditioned space below meaning the Attic and the house itself was part of the conditioned space but we did vent the roof again venting the attic versus venting the roof we're talking here about roof venting versus attic venting so now if we get a new moisture or air that gets passed here it's got this drying space and in fact we want airflow underneath that roof panel to keep everything nice and dry and to ventilate that space ok let me scroll back down here now even if you weren't doing the walls on your house you were going to insulate your walls traditionally you could still do this outside insulation on the outside of the house and then here's what the inside of the house would look like let me let me scroll down here a little bit here's a couple photos as we wrap the house and some metal and ultimately here's the inside of the house we didn't need sheetrock because all the insulation was on the outside we had to do a couple tricks to make sure that we didn't have any fire chases and that we met fire codes but here's the attic for this house the attic was basically a bedroom space this was all within the conditioned envelope and in fact instead of using ductwork we ended up using a Mitsubishi mini-split system to heat and cool the house but here's the here's the rafters these are structural rafters and here's the bottom side of the roof deck and because we have that out insulation this house incredibly comfortable and again we didn't need to use spray foam on the inside or some other ways to insulate that let me show you a couple images of this house then we'll wrap up the video but I wanted to show you what the finished house looked like in that cool house I had a lot of comments on Friday's video about how expensive I build my houses I'm really proud of this one you know we built this one for not much more than a lot of houses in America this is a house that was somewhere just a little north of $250 per square foot to build and look at this incredible house that we were able to build a small house not very big but some amazing building science and really some really really pretty and interesting interiors as well and there's the inside of the house guys thanks for joining me as we talked about how to make that change from traditional invented roofs to these conditioned and unvented attic spaces I gave you a couple systems but these systems are ultimately going to lead to houses that are much more durable much more comfortable and very very efficient thanks for joining me guys hit the subscribe button below we've got new content every Tuesday and every Friday otherwise we'll see you next time [Music] you

Channel: Matt Risinger

Views: 606,948

Rating: 4.8473992 out of 5

Keywords: attic insulation, attic ac, attic, attic remodel, build show with matt risinger, dumb attics, conditioning an attic, hot attic, cold attic, spray foam attic, attic access, ac in attic, heater in attic, how to condition an attic, running ducts through attic space

Id: F7D4Q3mjgdQ

Length: 17min 7sec (1027 seconds)

Published: Tue Feb 13 2018