How to Build High Performance Walls for Homes, LEED - PH - ZNE - Design, Insulation - EcoHome Guides

all right today I want to go over the wall assembly of the the demo house before we go a whole lot further you probably if you see in the previous episodes you know what's going on below grade so above grade this is going to be quite a bit different than most people are used to seeing so for the record there's nothing we're inventing here there the building science community has been studying the evolution of housing it's very different than it was 30 40 years ago what we're building so they're looking at what's working what isn't and why and what we should be doing differently so this is really this is us applying their solutions now we're not saying this is not the only way to build a wall it's not the best way to build a wall but it works so explain this how this works and that way you can go ahead and design your own walls knowing the fundamental rules that you should be following to make sure that they're going to perform properly and and last so first of all you probably notice there's a lot of insulation going on here and there is we have a normal normal stud frame wall bats in the wall cavities but the majority of our insulation is outside is is eight inches of raxil comfort board so the true our value of this wall not just the materials but when you factor in all the studs the actual wall itself is about our forty seven that's more than double what most building codes require and a lot of people think we're nuts for for doing that but given like we factor in the climate we're building in the cost of insulation the cost of utilities then if you think about you know a reasonable lifespan of the house this makes sense like this stuff pays for itself really quickly so for the science of what's going on here think of your wall as an environmental separator humans like that 20 Celsius 70ish Fahrenheit about 40 percent humidity give or take on the inside but it's not going to be that on the outside so this wall your wall is tasked with separating those environments no matter what's going on outside to keep it nice and cozy comfortable inside now get into a climate like ours here where we get extremely cold winters into the minus 30 Celsius and then in the summertime you're going up into the the 30s Celsius and it's like up to 100% humidity so that kind of a climate shift is a huge task to put on a wall to ask it to perform properly and last normally people are used to seeing a wall built the normal 2x6 wall insulation into the stud cavities a poly vapour barrier strapping maybe not and then drywall that's kind of what we're used to seeing and that vapor barrier is acting in two roles it's your air barrier but it's also your vapor barrier so meaning those are two very specific jobs vapor diffusion is moisture absorbing into the wall drying through to the other side that's your vapor barrier is there to stop that air barriers on the other hand are tasked with stopping air leakage through individual holes those are two very different things and we often confuse which is more important a lot more moisture is getting deposited in your walls due to air leakage than vapor diffusion check out our video on air barrier for more information on that so most builders would know instinctively that at least in a Canadian climate the vapor barrier goes on the inside of the building you want on the warm side of the insulation and that's right but where is that warm side we we design our houses in winter and then we build them in summer but we'd like we forget that it even exists because our because our climate shifts so so radically between seasons part of the year that vapor barrier is actually on the wrong side in a way because if you go down to Florida where the hot humid air is on the inside this air-conditioned cool and dry inside they have the vapor barrier on the outside of the wall to stop that human air from coming in so for us we put a poly vapor barrier on the inside and then you think about that that cool air-conditioned dry interior on those hot summer days the vapor barrier is actually on the wrong side so what the I say the building science community is proposing and what we're trying to do here is come up with a solution it's more of a year-round solution takes all those seasons into consideration rather than having like like snow tires we take them on and off every six months you can't do that with your vapor barrier so we really have to look at the whole year and every season and every challenge your walls going to face and there's a lot of different ways that you can you can build a wall to deal with that moisture that's a little bit more forgiving than that poly vapor barrier and what we're actually going with in this case is this Benjamin Moore to latex vapor barrier basically a vapor barrier paint or more accurately a vapor retarder because it's slowing the moisture movement so the that paint itself is stops more than twice the amount of moisture that's required by building code so it's twice as effective as building code is asking for yet it's still a little bit permeable to moisture so in the summer months you're not when you get that inward vapor drive there's a chance for the moisture to breathe through a little bit rather getting stopped at that poly and then creating moisture problems and condensation inside your wall with the vapor barrier paint like that it's actually breathing through to the inside a little bit or drying through where it does no harm so the poly that was doing those two jobs the air barrier and the vapor barrier our vapor barrier we've replaced it with the paint that leaves us needing an air barrier so in this case what we're using is this a delta vent si it's a moisture permeable self-adhesive membrane basically stick it on what put primer on the walls first the the barrier goes on tight so there's no wind pressure push and around it's going to open up nail holes stuff like that and then we've also added wherever the screws we're going to penetrate attaching the insulation these small squares of with a delta flex band it's this thick rubbery membrane they'll basically seal up around the screw holes so that we're not going to get air leakage when we're attaching the exterior insulation and while we're on that as you can see we've got 8 inches of insulation but it's broken up in two courses what we've done is we've attached the first four inches with one set of strapping vertical sorry horizontal so that the additional four inches here can get attached vertically that's leaving basically a drainage plane and airspace and interior to let water drain out and it can moisturize and leave sort of natural air convection is gonna have cool air coming up so we've got an opening through here as long as I can leave in the top that's going to leave your walls the ability to dry up so the way that we've attached it here as you can see we've got the four inches of insulation attached with one set of strapping and then an additional four here the reason for that is basically it's thermal bridging if had we had a screw penetrating the entire eight inches of insulation right into the wall assembly those the metal is a conductor so that's going to act as a heat conduit basically sucking heat right out of your house so this is the reason we split it up into four inches of insulation attached to the wall and then offset with the second set with another set of strapping attaching to that that first strapping there and I say that that breaks up that thermal bridge had we not done that it reduces the overall our value by probably about thirty forty percent so just way more than is tolerable just it it's not even worth bothering putting it on if you're going to have that much thermal bridging through it and there's there is other ways to do this we we chose the strapping eye we're building better houses where we are in 16 salacious this is finding its way into building codes people are getting that it's worth the investment and insulation so and the best place to put it's on the outside what we've done here was a couple of reasons one was to try and keep it within the realm of what's familiar to builders insulation strapping is but it was a little bit more work there is other ways to do it I say there's there's fiberglass clips that you can install right on the wall sort of sandwich was the insulation in so it's not a thermal bridge they're pretty expensive and but having done this already I don't know it's a toss up a lot more labor this way blower costs so they say just a different way to try it see what works for you and then having that wall assembly like that with that airspace in the middle we were a little bit concerned that there was going to be a convection of air inside it that leaves a cavity of air here so this is any leakage there's just a writ a risk of it causing heat loss so what we did actually was we got the second Delta vent s membrane the black one here on the outside in the wall it's actually taped underneath to this one and then sealed again at the top same thing over all the window openings so it's the drainage plane if any moisture gets into the walls any water leakage but at the same time it acts as an additional air barrier now when we were actually we had to seal up the house and finish our sealing we were doing at our blower door test that's where the house is depressurized so you can measure air leakage a fan installed on the door blows out and gives you a chance to go around the house and you can find all the little holes and fix them it's a great opportunity to really improve your the air tightness of your house so when we did this our blower door test if we only had the gray membrane on we didn't have this one on yet and it even with that we were already about five times more airtight than the average house being built today so overall what we end up with here is it's a wall that's much better insulated than most new home construction no poly vapor barrier something of the paint on the inside so it's a little bit more breathable so it's more durable and and we're way more air tight than other houses out there so we've got a super insulated wall it's going to be durable it's going to last and frankly it's a it's it makes financial sense because the added insulation that we're putting in the wall yeah it's going to cost you money but the payback period isn't 25 years down the road because you're saving energy instantly so I mean for example if it's going to cost me an extra $1,000 a year on my mortgage to build a better house and yet I'm if I'm saving $1,000 a year on utilities I'm really not paying any more so it's really worth looking into beefing up the exterior insulation of your house for more information on any of the stuff we're talking about here check out eco home building guide go to the keyword search box air barriers vapor barriers insulation we've got a guide in there that sort of walk you through the different characteristics of different materials how important things are what's important what really isn't stuff like that so anyway hope it works out for you thanks for watching you

Channel: The EcoHome Network: Green Building Resources

Views: 136,449

Rating: 4.8403044 out of 5

Keywords: Walls, Framing, High-Performance, Eco-Friendly, How To, Vapor Barriers, Air Barriers, Mold, Mould, Prevention, Insulation, Hemp, Code, Construction, Building, Homes, Houses, Passive House, Passivehaus, Building science, REMOTE wall system, Vapour barrier paint, Vapor barrier primer, Vapour retarder primer, Vapor retarder primer, Liquid applied vapour barrier, Exterior insulation, Passive solar, Passive home design, LEED, ZNE, NetPositive, EcoHome, Sustainable, Green Building, Energy Efficient

Id: Z-yasiKVRms

Length: 12min 1sec (721 seconds)

Published: Wed Aug 12 2015