Roof Top Insulation

on the build show today we're talking rooftop insulation we're back at my personal build we called this the monopoly house in a previous episode and we're going to show you today how we're gonna blanket the entire roof of the house with a thick blanket of insulation today's video sponsored by alice insulation let's get going alright guys if you saw my previous episode you saw how we frame this house I called it the monopoly framing and you can see it on the second-story roof right here we've framed the wall so the walls that go straight up to the roof deck without any overhangs traditional framing has rafters that poke over top of the second-floor walls to form that overhang but in our case we wanted to run our air and water barrier all the way continuous from the foundation all the way to the top of the ridge now this allowed us to then have a continuous insulation running also on the walls up to the roof now today we're afraid we're gonna focus really just on the roof insulation and we're at the pop-up that we formed in the staircase going from the first floor to the second floor this is slab on grade construction and what you're seeing here is that Oswald and the guys from Madera framing put on top of this framing right here our first layer of insulation now this is poly iso insulation from atlas roofing rooftop installations use them all the time in commercial buildings but it's uncommon to see it in residential buildings what we're doing is we're making a nice thermal break on the entire top of a house if you watch my previous videos I make this akin to putting a big down jacket on overtop what we want to do is break all that thermal bridging all the conductivity from our wall studs and our roof rafters and then also this is going to be an unventilated or gable vents on this house everything from this side in is gonna be part of the air conditioned space of this house so what we did on this on this little pop-up here is we ran all this rooftop foam continuous now this is 2 inch foam and we have a piece for you here again this is poly ISO so it's got a very high r-value per inch and we're running 2 inch thickness pieces and this rooftop foam is specific to rooftops because it's got a different face err than what we're gonna use in the walls this is a fiberglass face or you can see here so no mold growth no water issues this is fiberglass which is going to face the top and the bottom on the phone now if you kind of get down here you can look and see that here's our wall that comes up and this is the start of our roof plywood on top of that roof plywood continuously we put two inches and then to form the overhangs in this case we're using some lvls now we use these four studs on the inside of the house but simply what we're doing here is forming the overhang and we've got a little bit of a smaller overhang here at this very top section this is going to end up being about 16 inches in the finish once we get all our hardy soffit and facia on here and we'll have a metal roof on top of this section now on the rest of the house you're going to notice that the rafter tails stick out 24 inches and again we're using an lvl detail so once we put that down we put the LDLs down now we shimmed on top of those because those LDLs in this case we're an inch and a half thick and this poly iso is 2 inches we shimmed it with a half inch layer this is actually 7/16 zip all this is do is just shimming up for us and then you see oswald's fit in between there another sheet of poly iso so now we actually have four inches of poly iso roughly our 28 on the roof top deck and then we're gonna put another layer of zip sheeting all the way across this so that now I've got my waterproof layer and I've got my roofing that will go on top of that so in other words we've got an umbrella that's going on the house and insulated umbrella on the top here let's pick up the video tomorrow or the next day when we get started on the rest of the roof and I'll show you what the rest of the outriggers look like alright guys it's actually been 2 weeks and not a couple of days a little has changed in the world but here's what we're at before when we made the video before we finish this roof and you can see we've decked it now so we've got our 4 inch poly iso and then I put another layer a zip on top so now I've got this beautiful umbrella happening over this area we've got about a 1 foot overhang now let's talk about the main body of the roof and you can see it under construction now we did it slightly differently on the main body of the house so first off you can see when we put those lvl rafters or tails out so to speak we ran those 4 feet in two feet out that's a 6-footer and when we cut those we ripped a center section down to two inches and then we lag those into the roof with these six and three-quarter lags from specs that's a power lag that that basically acts like a lag screw but the beauty of those is you don't have to pre-drill them so those are lagged in now we did it with two inches so that you can see here we could infill in between the panel's so now we've got these rips of insulation that are roughly two foot on center and then that poly I so you're seeing we're cutting that basically with an insulation knife the fiberglass face or cuts relatively easily so does the poly iso fitting that in between now we've used a washer head on there this is a rodent house washer head they make a bunch of good products for installing insulation but this first layer we really just tacked it on as all we did we're just looking for it not to move as we walk on it the second layer we didn't use washers because we've got that backstop with the lvl so if you look down the roof this way you can see that first layer right there has the backstop and is stopping where it hits the lvls now notice this right here we've staggered the seams this is really important so this sheet right here is running opposite to this sheet and that seam is staggered in both directions right this seam here is several inches back and this seam here so we'll have very little crossover you really want to do that whenever you're using rooftop foam or really any insulation on your rooftop because foam can shrink the the datasheet if you read the datasheet is going to show that it's going to shrink less than two percent that's kind of the industry standard but in reality it's gonna shrink more like no more than one percent or maybe even a half percent so in these four by eight sheets you're talking about these over time potentially shrinking up around an eighth inch in between the panels now it could shrink slightly more than that but usually understand that's happening if these are in contact with the water they will end up shrinking more which means that when we have it delivered to our job site you can see all of those panels over there it's gonna come covered from atlas when they deliver it you want to leave it covered in two time to install and we didn't start this install until after the rain that we had stopped and we knew that we were gonna have a day or two of dry so that we can install both panels and then put our second layer of zip system sheeting over top now let's talk about our value I actually messed it up in the earlier part of the video I incorrect r-value I did a little research after I filmed that first section and because of thermal drift it's kind of an industry term meaning that this poly iso is not going to stay at the same R value when it was born as it will for the rest of its life it's gonna drift a little bit so it's gonna start at a slightly higher r-value and come down to a final or long term thermal resistance they actually use that LTR are on the website and this one at 2 inches is going to be eleven point four when it's all said and done so in fact my roof is going to be twenty two point eight long term thermal resistance it ends up being that after about six months from the time it was made and then it's gonna stay that way for the long term of the roof so it will lose a little bit of our value but it's going to stay constant and after that one thing I really like about Atlas poly ISO is that it's a really stiff insulation there's no compression that happens with this so as we screw this down for instance with those fasteners with those washers I was telling you about earlier we're using some Phillips screws to screw that down this is actually a big part of the job is thinking about all the different fasteners you need I like these Phillips screws because when you stick them on the bit they have this stick fast technology and they actually kind of stay put on there so they're really easy to use you're not worried about that bit and that thing falling off but what's happening here is when we screw that down into the foam you can see that foams got some some resistance it's got a pretty high psi value so that it's not going to compress and that makes it easy to walk on and then ultimately when we screw down these later we're coming back with some long screws so these are specs power lags similar engineering resistance to a traditional lag but no pre-drilling required a nice fat washer head on here so it's really gonna grab on that final layer of zip someone asked me in the comments in an earlier video what's the difference between the green and the brown this Brown zip you're seeing here is a 5/8 thick and that's what my engineer wanted to use in my roof so if you look in the backside of the roof here where we've covered the insulation you're gonna notice we've chalk lined out where all the rafters are and then we've used these eight inch screws to go through that four inch assembly through the 5/8 decking and then boom it's gonna actually lag into the rafters below and hold everything down so now I've got a big thick umbrella on the house and I've got a big thick raincoat now let's walk over here for a second and let's talk about this overhang now we're gonna get into this overhang detail in a future video because we still have a ledger board and we still have some more framing going on on this but look how strong this thing is I don't even have all this zip screwed down yet and you can see it is not moving at all the other thing you'll notice is look how this 2x4 which is out on the rake there is shorter than these what we did was we ran these long just like you're framing a deck string laying them and then cut each one individually and that allowed us to get a perfect two-foot overhang nice and straight as you look at that from the ground again we've got some further details on that I'll get into the overhang details on a future video but today we really wanted to focus on this roof insulation last thing I do want to mention is we're still going to use cavity insulation on this job this is not a house that has only exterior insulation but what this is doing is this is creating a thick blanket of insulation so that there's zero chance of condensation inside the building and when you go this thick on the outside really you could do this detail in just about any North American climate zone all the way up to the cold north and it's going to give us enough thickness of insulation that we won't have any issues with condensation happening inside the building and as you can see now a continuous blanket all those rafters that normally would just have insulation between the rafters all those are covered over so I've got a nice thick blanket of insulation guys I think that's it if you've got any comments below shoot me a comment hopefully I'll try and answer as many of those as possible I'll put a link to the Atlas poly iso insulation website as well great people over there and having a ton of fun making these videos you can see we got a week outa just a beautiful job under construction and even better than I'm actually gonna get to live in this house is the first house in my 25 years as a builder that I've actually built something for my family so I'll tell you I feel giddy every morning waking up and getting out to the jobsite here super super fun and to do these details it's been it's been a dream come true guys if you're not currently a subscriber hit that subscribe button below we've got new content every Tuesday and every Friday follow me on Twitter Instagram other wise we'll see you next time on the build show you

Channel: Matt Risinger

Views: 362,622

Keywords: insulation, matt risinger, build show network

Id: yTbMVdmnNlw

Length: 12min 37sec (757 seconds)

Published: Fri Apr 10 2020