Air Sealing for a Garage Ceiling

Welcome back. I'm Jake Bruton with AeroBuilding in Columbia, Missouri. And today on the Build Show, we are at our Spring Valley Aero project. And surprise, surprise, we're going to talk about air leakage. I realize that I talk about air leakage a lot. I write about air leakage a lot. We make videos about air leakage a lot. Normally when we're talking about air leakage, the thing that we're talking about is energy conservation. So by controlling the air that leaks out of your house or infiltrates your house inward, we can cut our energy bill. If I have total control over the air that's inside my house and I'm not leaking, I'm not paying to condition new air. You've heard that before. That's a very simple concept to wrap your mind around. And in say this project, we're 0.3 ACH 50, which means we're one-tenth of the allowable air leakage by code in our market. That ACH 50 number is at air exchanges per hour at 50 pascals of pressure. So that's just a testing metric. So just think of it as we have in the entire envelope of this house, that's walls, floor, ceiling, basically a business card worth of leakage. That leakage, we're only talking about energy efficiency. I mean there's concerns for we have control so we have health issues and things like that. Those are concerns that are very minor. We're really trying to just gain control. Here in the garage, we're trying to limit air leakage for another reason. We're still trying for the energy efficient thing, but we're also adding in the idea of safety. This is the garage. There could be cans of gas, running cars, paint, cleaning chemicals, whatever. Think of all the nasty stuff that you keep in your garage. You don't want to breathe that stuff indoors. So you can see that we have zip sheathing on that wall. We have zip sheathing on this wall, and that we're adding zip sheathing on the ceiling. And the reason that we're doing that is we're just trying to divide this space from the conditioned space. Upstairs, there's a whole apartment above us basically, a couple bedrooms, bathroom, kitchen above us. That room's air barrier is just drywall on the ceiling, and it works. The problem is if it stops working up there, that drywall air barrier, all it is is a ding against our energy bill. But if the air barrier here stops working, it's a ding against our energy bill and it's possibly a health issue. So we've taken the time to zip the walls between conditioned spaces, and you can see here next to the ladder, that white that you see is actually our blown in fiberglass insulation. That insulation is insulating between here and outside. So we have two separate sections of the house here that are interior. This is a stair tower that leads to the space above us. Behind us over here is our main house. So those got zip sheathing before we started building the walls out here, and we actually built both of those structures before we framed any walls out here so that we could completely air seal them. You can see that we also have spray foam insulation at the sill over here. That is entirely, we messed up one of our details and forgot to take care of air leakage there. So we just had the insulator come in and splash a little bit. There's space between the two by six wall you can see and the zip sheathing, so we're able to seal that completely. That was our last ditch effort at the last minute. Oh man, we forgot that. So we've insulated those spaces on the other side, we've air sealed them on this side, and then that brings us to the ceiling. Yes, again, we could rely on drywall up there, but we don't want to make it just that. So we're going to zip this and before we set our trusses on top of this, we actually added a little zip flange all the way around and even on top of our beam so that then we can infill with our zip board, tape over it. It's all sealed, it's all dividing that upstairs space from down here. Next we'll get drywall, that drywall will get completely mudded and taped, it'll look like normal. And rather than punch a bunch of lights into this just for safety reasons, we're going to run all of the electrical on the ceiling for this in conduit. So that means we have a wire penetrating our fiberglass insulation over here. That wire will come up, feed in conduit to a garage door opener, it'll wrap around the beam and back to the other garage door opener. And then if you look over here, we have a 14 gauge wire that's coming out of the wall that'll run the lights in the whole area. So we've taken the time to install that stuff underneath. There are a couple other ways that you could do this. We could go to the top side and we have Advantech subfloor up there. It's possible that we could liquid flash the seams of that, or we could tape the seams of that. There are some problems in process for us that we're not really okay with there. Number one, none of the tapes or sealants are specifically made to stick to the Advantech, so there's a question mark there. Number two, we would have to do that at least on the perimeter where our walls are going to sit before we stood walls up on the second floor. That's a long time for a tape or a liquid flash to be up there with people working on top of it and it survive. Number three, you have a lot of penetrations that have to go through that you have to deal with. So we could do it from the top side. Next, before we installed all of our insulation above us and our zip panel, we could come in and spray foam the bottom of that. We probably could lock the whole thing in. We'd have one monolithic layer of spray foam. We could do it after all of our penetrations, all of our electrical, our plumbing, all that kind of stuff is already through. We could spray it, probably seal it just fine. The issue with that, this is a little less than 1,000 square feet that we'd be paying for two to three inches worth of spray foam just to be able to lock all that in. That's a pricey endeavor. That's more expensive than the little bit of zip that we have on the ceiling and the day worth of installing. So by moving this down here, we're able to have all of our electrical, all of our plumbing, actually all of the electrical for the whole house runs through here and to a panel over here. We're able to have all that migrate through there and then just on the bottom we air seal it. We think this is a bomb-proof method. We think that this method is going to protect our family for the long term. We're not ever going to have air leakage from here up into the space above. I really think that this is something you should be concerned about, the air quality between here and the house because nothing that happens out here is good air quality and we want everything that happens inside of our home to be good air quality. So take this into consideration, do with it what you will. Thanks for watching and I'll see you next time on The Build Show.