An Awesome Wall Assembly for Cold Climate Construction
Belt, suspenders, rainscreen, and redundancy make this wall awesome.
This dronezone driveby is the fourth in a series on a gut rehab and substantial addition to a 100 year ols foursquare home in Minneapolis, MN. All of the episodes are collected here.
00:02: Here we are, just under two months into construction and it's gone from excavation to framing to turning completely green. We've already got our electricians and our HVAC guys inside. Our plumbers have already been inside. We're just clicking along at a really great pace.
00:25: One of our goals in this project was to show that you can develop a house in an urban lot that doesn't overshadow the adjacent houses, kind of towering eyesore that makes all the neighbors angry. It's a 412 pitch, and we used the 412 pitch because we wanted to keep the profile of the house low.
The only downside to this roof design was that we weren't able to make use of a ridge vent to provide the ventilation for the attic. That meant we had to stick with soffit vents and a few turtles up top, but still fewer than what it was.
01:02: So, when we talked about what makes the OA Awesome Wall so awesome, it's a combination of parts. R 12-ZIP System is obviously a core component in that system.
But what we add to that is the Benjamin Obdyke Home Slicker, and that is our ventilated rainscreen. It's a multi-directional system. It's not just channels between strapping or battens where it's just going up and down. You have to make sure it has a release point. It goes left, right, diagonal, etcetera. So, if somebody accidentally screws something up, if they didn't leave a wide enough gap at the top where the cladding meets the frieze board, we're not gonna end up with a wall that isn't venting properly.
01:48: You also see a bunch of white furring strips going up. This is another component in the system. That is what's going to hold the solid cellular PVC cladding and trim system, so that they stand off from the wall an extra half inch or so. This is important because this is cellular PVC cladding. Cellular PVC moves a fair amount, and so we need to give it space to do that.
So, those corner boards overlap the siding. The siding runs back behind them, and it gets about an inch gap on either side of the wall. The siding is pinned in the middle, just like a typical vinyl siding install so that it can move left and move right. The board and battens are pinned in the middle and they move up and down, except at the deck where they're pinned at the bottom and they only move up. So, the real trick with this system is just knowing where to pin the claddings so they can move in the right direction.
02:47: So, solid cellular PVC, this is called Celect and it's from Royal Building Products. Those corners are single piece corners, so they are already pre-90'd and they come in very, very long runs if you want them. They make for a just a beautiful clean edge, but more important than that, the entire cladding system has a Kynar 500 finish on it.
Think of it like an automotive finish, or a metal roof where you are putting up a product that will last for a very, very, very, very long time. It's a lifetime warranty on the product. That Kynar 500 finish has a 25-year warranty against 5% fade, and that's saying a lot.
03:31: This is another cool component in the system. This is a vinyl window from Sierra Pacific that has an extruded aluminum exterior and a solid wood interior. That's cool because when we're doing energy efficiency, we look to vinyl windows to be more energy efficient. Unfortunately, aesthetically, they're still ugly.
So, we have the attributes of a vinyl window but we get the extruded aluminum on the outside for the durability, which makes the consumer happy, and we have the solid wood interior, which makes the consumer happy and it's aesthetically beautiful. So, it's a win-win in all three layers of the window.
The other thing about this window that I like is it doesn't have fold out flanges. So when you're installing it, it's a solid vinyl frame, makes much easier to square up in the opening, much easier to install.
04:23: Like everything else that we did in this system, we were trying to come up with multiple redundancies, because the reality of our industry is that things get screwed up and we have to assume that 5% to 10% of any, whatever gets put together will get put together a little bit wrong.
In this case, you could put it together 40% wrong and we would still have a ventilated rainscreen. And that, to me, is key in making sure that that wall actually is able to resist any rot moisture accumulation over the next 100 to 200 years.
So, we call it, the OA Awesome Wall, a 200-year wall because making that wall fail at this point becomes incredibly hard, even with people making mistakes along the way.
—Michael Anschel owns Otogawa-Anschel Design+Build in Minneapolis, Minnesota