Challenges (& Solutions) in Custom Passive House Panelization

Alan Gibson is Manager of G-O Logic LLC of Belfast, Maine, a 35-person design/build firm, general contractor, and panel manufacturer. He holds a BA from Brown University and is a Certified Passive House Builder and Designer. GO Logic’s first Phius-certified home was completed in 2010. He is currently secretary of the Phius board of directors and chair of the Phius Alliance, and speaks widely on passive design and construction.

Check out the transcript:

All right. Well, thank you all. Really excited to be here. Excited for the Q&A at the end of my presentation. I'm going to blast through this pretty quickly. So this is just saying what Bev just said. We are a general contracting company design build. We'll general contract projects on the Coast of Maine. We will deliver panelized shell packages throughout the Northeast, including New England and Eastern New York, and we could even go into New Jersey for the right project.

We have been panelizing in earnest for about four years, we're always learning. This presentation is in my view, I've learned a lot from people who have been doing this for a while. I want to share information, I'm not hiding any secrets here. I really think panelization is the way the industry needs to go, so I'm very open source and open to questions.

Bev also wanted to make sure I mentioned panelized retrofits, which I've been looking at for a while and excited about, I've involved in one project, excited about those possibilities. So at GO LOGIC we've developed this line of home called the Go Home, we also do custom work. The Go Home come in lots of different shapes and sizes, all kind of in a design family and we've penalized most of these. These are predesigned homes, but we let people customize them, which is kind of to our detriment in a way and we're trying to steer people into doing designs that we've already done in the same way.

And we're also developing designs that will have more strict rules, I would say, because partly for this reason, we are interested in panelization. We're doing custom panelization. There are other ways of doing it that are more standardized, but we're interested in panelization partly for this reason what's on this slide, which shows that among all major industries, construction lags behind in terms of productivity, the amount of work produced per hour of work.

And I think there's a lot we could talk about with this slide, but suffice it to say that the industry's been talking about going in the direction of some kind of industrial scale for building for a long time. And it's something that's motivating to us.

So this presentation is going to be a little bit about how we do our panelization, and then we're going to show a case study of a recent install project. So here's our crew in our shop, looking at a presentation on Swedish panelization. I visited Sweden a few years ago with Scott Hedges, who is my Swedish construction mentor. He runs a website called ByggHouse, B-Y-G-G-H-O-U-S-E, where you can learn a lot more about Swedish panelization and look at some of the products they have on offer.

And the Swedish system is quite well developed, about 80% of homes in Sweden are delivered penalized in a similar way that we do it. And others it's a very mature ecosystem. There are general contractors all over the country who are familiar with it, who install the panels that are made at True Factories. They've been at it for since the 1920s. And there are a lot of reasons why it works there. Sweden's a more egalitarian society, they're used to the Ikea type delivery system, there's lots of competition, lots of companies doing it.

And they're producing basically, passive house level homes with about half of the labor hours that we're taking to do homes. So it's pretty cool to see how it's done there and it'll be a while before we're there, I would say, but that's what we aspire to.

I also wanted to say that, I just want to acknowledge my crew, my company for the work they've done to move our panelization process along. I give them suggestions and ideas and projects to do, and they really figured out from the designers down to the guys here on the shop floor. And so just wanted to acknowledge that, and that's been really exciting about getting into the panelization. So here's our little shop. It's not very automated or mechanized. It's basically we're using some framing tables and some basic tools and some lifting equipment to build panels.

One thing I wanted to talk about real quick is installing windows and panels, which I think is really important, especially passive house windows. There's a lot of value add that goes into how they're installed and treated in the wall. I get calls from architects who say, "Hey, can you install these fancy European windows in our building because my builder doesn't know how to do it." We have spent a lot of time figuring out how to install windows. Here's a session the crew did, a workshop basically on how to do it.

We preassemble windows, this is a Swedish trick. You start out with a window and you put a buck around it. You flash it, you put trim on it. Here are some, they're they're upside down in this photo, they're the first thing that goes on the table and then we frame the wall around it. And there are a lot of advantages to that in terms of how labor is used.

Real quickly, how our wall is assembled. This is a two by eight or a two by six stud wall. This is the exterior we're looking at. We have the window preassembled in there. We put a sheathing layer on it, that's the airtight layer. Then we add 5 1/2 inches of wood fiber, and then it's not shown in this, but we will put a WRB on and then a strapping layer.

And that's basically what we ship. And then sliding is put on in the field. Here's what it looks like in real life. So on the left is the interior of the wall, that's the two by eight stud wall. We've got gaskets on it, which creates the air seal between panels. Then we have the structural sheathing layer and then we have the wood fiber, then we have the vented strapping.

And on this particular project, we have another layer of sheathing on the outside because it's getting cedar shingles siding. So there's a lot, there, that's a complex assembly. There are a lot of ways to make an R50 wall to meet this works well in our I'm at zone six. I've done a lot of them and looked at a lot of them and they all take the same amount of work and effort. There's no real easy way of doing it.

It is a basically, as you can see, in all wood based product, so it's low carbon, which we used to use a lot more foam. We've shifted almost entirely away from that and I'm really happy about that. So now I'm going to get into talking about this project. Here is the site. This is Penobscot Bay in Maine, a beautiful little peninsula that was in the client's family for a long time. This was existing on the site, basically an uninsulated summer house that we removed and replaced it with a brand new passive house.

So one of the big things, one of the big learning curves in panelization is to go from your architectural drawings to a 3D model, and then to shop drawings. And this is something that we've taken on in the last year. So here are elevation drawings of this particular house. It's a two storey 2,000 square foot home, this is in Revit. Is what we use for design. And then we purchased cadwork software and it creates this beautiful 3D model that has every single thing in it that you are going to build.

And if I had had this tool for the 20 years I was a framing carpenter, it would've been wonderful and I dreamed about it. Wouldn't it be great to have a drawing that showed where all the framing goes so you don't have to figure it out when you roll the plans out on the deck and try to lay things out on your sticks of wood. This is an incredible tool, and it's pretty essential for doing any kind of modular prefab.

And from that, you get a lot of 2D outputs. Here is a plan view of all the walls of this house. And from that you get really detailed wall plans. Here's the framing plan shown in elevation, in section, and you'll notice every piece is numbered. And if we had a CNC saw, we could output the file to that, and it could cut every piece, and depending on how sophisticated you are, you could label everything.

We haven't gone that far yet, but we cut everything by hand. And this is the actual cut list that's generated. And that's a lot of pieces. That's pretty complicated. And I think part of making this process more streamlined is to make this simpler. And there's another method of doing panels, which is in modular panels where you may have a design, or you may have 24, 30 standard panels. And then it's more of a manufacturing process of producing X number of number fours, X number of number eights. And I think that's something that will be part of our business moving forward as we develop that.

All right. So here's one of the first days of this installation. We're on the site. The amazing thing is that all of these walls look exactly like the model. It's just amazing how that works. And one trick we learned from watching videos about how the Swedes do it is anything you can put inside the building at this stage, you try to do. So in the foreground, you see these pallets of windows and those windows are too big to put into panels. And that's something you have to look at in your design. We don't do a lot of architect design projects because there are large walls of windows that you can't penalize, and you end up spending 10 times more time on site doing that.

But in this case we just have a few of them and they dropped well, rested softly on the slab. This pallet of windows that will be installed, it's right where they're going to go. It's going to be out of the weather as soon as it's closed in. The Swedes take it a couple steps further. They will actually put drywall interior framing and even mechanicals in with the crane since it's there, so you don't have to log it in by hand later, saves a ton of labor.

So here can see the model on the left, and in reality on the right. You have to rotate the model around 180 degrees in your mind to see it match up exactly because the photo's not from the same vantage point. Here's a closer shot of it, a broader shot. Still a lot of standard carpentry stuff, raising walls, straightening things after you set the panels in.

So from there we go to the second floor deck panels, and they're pretty simple, eight feet wide by these are about 30 feet long. They flat pack on the truck and they get hoisted into place. There's the finished deck.

Then we go to the second floor and in this particular design, you can see how the second floor basically extrudes up from the first, the main box extrudes up from the second floor. That's pretty straightforward, but we have this shed roof section that goes over the kitchen. And that's a little challenging pot spot that I want to talk about for a second just as an example of what you have to think about ahead of time before you start building anything.

You see on the left of this image, the shed roof portion of the roof. And here's a section of that through there. And the tricky thing is how to get the air barrier to connect from the outside of the exterior wall on the first floor to the exterior wall on the second floor. And you can see the green line here is our sheathing that goes up the outside of the exterior wall, over top of the top plate down to the top of this ceiling framing. And then up to the sheathing on the outside of the second floor walls.

We have revised this section a number of times, but we've settled on this one. And the cool thing is that my structural engineer drew this. So we've been doing air tight buildings for so long that he actually puts our air barrier in his drawings. And that's pretty cool.

So here's the site, here's the panel coming in up to the second floor. Here's the second floor walls in place with the start of the attic deck. There's a full deck across the attic for essentially a third floor. And I want to show this because because there are a lot of things related to the panel assembly that you have to learn rigging, crane signaling, safety. The order of operations is all really important and we've learned it along the way.

The site organization is important. This is a tight narrow site, so you have to think about getting the mobile crane in there. We own our own truck and trailer, so we can transport panels as close as we need to. You've got your dumpster and your porta potty. You've got to fit in there and a place to lay down the panels. So it's another thing that's different about this type of delivery.

Here's the second floor deck in place. And I love that there's a laptop there, which is in this system just as essential a tool as a nail gun or a level along with the spray can so you can and right danger along the edge so people don't fall off. So the roof system, there are different ways of doing this. We do a truss system typically, although we are developing a roof panel system for peaked roofs.

And we could go into this later maybe, but here's another tricky spot where the air barrier has to be continuous from the outside of the exterior walls to the underside of the roof framing. And here's a section of that. So we use in this case, the scissor truss up there and the air barrier has to continue to the underside of that scissor truss. And we do it like this, so in green, again, the exterior sheathing comes up, the outside of the wall, goes across the top plate and then connects to in this case, a membrane air barrier on the underside of the truss.

Speaker 1:

We've done it a few different ways, but we've come to wrapping the profile of the trust with sheathing on the inside to make that connection. You can see it here. This cable end wall is sheath, the profile of the truss' sheath. There's insulation behind it. And there's a flap of tape there ready for the membrane that's going to come in later.

Here it is on the other side with a little more detail, you can see that Dave land panel was done in two pieces because we are at our height limit for the first one. And then the little triangle has to be built on top of it. And those pieces of sheathing are pre-cut and just tacked in place ready for that little panel to be put on top and then those pieces will get lifted up and attached and you can see the tape on the lower side of them ready for the trusses that are about to come in.

There's another challenge. I don't know why, but we always get sites with very narrow roads with tight trees on both sides and no one ever wants to cut a tree, which is fine. When the trusses come down the road on this truck, it could be challenging. And apparently this driver, I didn't see this, but the driver was using the trees to push the load around on the flatbed by going backwards and forwards so he could snake through this driveway.

Here's a crew, once these trusses are assembled, after this, it's a pretty standard sheath roof, put the roof trim on process. Here is a view of the finished facade, here's the interior taking advantage of those views, of those big windows. And this is not the same house, but I wanted to put this in to show you what a finished house looks like. This is another project that we finished recently and that is it for the slides.

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