Alex Henderson of The Last Straw spoke with Raivo Vihman of Haystack Joinery and Andrew Frederick of Croft about their recent collaboration designing and building a house for a farmer in Northern Maine. The project merges timber frame and straw panel construction, creating an innovative hybrid system that solves a number of key heavy timber construction issues. The result is a speedy build, a beautiful open gable space, and a huge amount of carbon storage.
This project is located in: Köppen–Geiger Zone Dfb, ICC Climate Zone 6a, in an area with 8104 Heating Degree Days and 244 Cooling Degree Days.
A House for a Farmer is being constructed in a town called Trescott on the Northern Coast of Maine near the Canadian border. The house is a collaboration between Raivo Vihman of Haystack Joinery and Andrew Frederick of Croft. Raivo is a timber framer who has well over a decade of timber framing experience and enjoys pushing the limits of traditional timber systems. Andrew runs a burgeoning carbon capture company called Croft, which is currently producing structural compressed straw panels. The two friends, both Mainers themselves, looked to the collaborative design-build project as a chance to explore the opportunities presented by combining timber frame and straw panel construction systems.. The Last Straw had the pleasure of speaking with Raivo and Andrew to discuss the process.
The house was designed with a specific problem in mind: the structural redundancy and material waste characteristic of modern timber frame construction.
In most U.S. climate zones modern building codes require timber frame homes to be wrapped in insulation after they are framed. This often means building a stud wall system with insulated cavities directly outside of the timber frame. Since this stud wall would itself provide enough structure to carry typical building loads, the timber frame, though beautiful, becomes structurally unnecessary. “Probably 99% of the time timber framing is jewelry,” said Andrew, “and it’s incredibly expensive and resource consumptive jewelry. No one is more aware of and sensitive to that than Raivo.” Raivo describes the situation: “For me the biggest downside of timber framing is that for insulated structures like houses there’s so much redundancy…timber framing is a perfect system for uninsulated structures like barns and outbuildings and anything exterior to the insulated cavity of a house, like the entryway, the breezeway, or the porch. For all of these, timber framing makes so much sense. But in the modern version of housebuilding, getting enough insulation means building very thick walls… for a long time I’ve been wanting to figure out a better way to go about building a house where there is still exposed timber work because it’s really beautiful, but without the wastefulness of building a whole timber frame and then building essentially a whole other house around it to support all the insulation.”
Axonometric diagram illustrating minimized timber frame structural elements, ridge beam, and continuous straw panel envelope.
On this project, Raivo and Andrew addressed the problem of redundancy by minimizing the timber frame, using it only where it is structurally necessary and enveloping the structure in Croft’s system of structural compressed straw panels. The main structural functions of the timber frame are to support the ridge beam that carries the weight of Croft’s roofing panels and to support a loft at one end of the building. The structural straw panels meet all other structural and insulative needs. “Typically to get a clear span building we’re engineering an absolutely gargantuan structural ridge [beam],” said Andrew, “This allows for a clear span gable space and keeps the walls from bulging outward under the downward pressure of the gable roof. With this house we eliminated this huge structural ridge [beam] and went to a very lightweight one which is picked up every 12 ft by Raivo’s timber frame.” He described how this solution might be taken further: “I think we could keep going and essentially rejigger the whole roof system so that the panels are oriented differently.
Instead of being oriented like rafters, which is what we did, they could potentially be oriented like purlins and we would have zero structural ridge involved and zero thrust because Raivo’s structure is taking care of all of that.”
The result of this hybrid timber and straw panel design is a simple and elegant gabled house with two exposed timber bents constructed using curved cedar members. The footprint is relatively small: 20 ft x 36 ft exterior, which, given the 16 in thickness of the walls, makes an interior dimension of 17 ft – 4 in x 33 ft – 4. “I think we’re both really really into the idea of small houses and pushing people to think smaller in terms of their needs,” said Raivo, “The idea of offering something on the smaller side that is thoughtfully designed. The hope is that people would respond to that, and realize that, oh yeah, that looks really nice.”
An uncompromising commitment to craft and close attention to detail run throughout the project. One notable detail- the way that the timber columns meet the straw panels and interior wall finishes- is designed to solve another common issue in timber framing: the difficulty of running electrical wiring through or around the timber structure. Raivo described the detail: “In a typical house all of the trades that come in after framing have to deal with the redundancy of overlapping wall systems, and the timbers are usually in the way of the wiring. Then the sheetrock has to get scribed around diagonal knee braces. There are just so many layers of added complexity to finishing out a timber frame house. So to me that’s the real beauty of having this hybrid system; you have all the beautiful timber work, but it’s not in the way where you don’t need it. In this build the timbers stand inside of the panels and the panels lock to the timbers from the outside to make a completely zipped up envelope. We designed it so that the inside faces of the panels were a half inch away from the outside faces of the timbers, so there’s what is very similar to a standard conventional stud wall that’s there about a half-inch out from the timbers. We then nailed 2×2’s every 16 inches up the face of that interior wall of the panels. Those 2x2s bridge that half inch gap between the timbers and panels and create a mechanical chase. So there are no wiring issues. You don’t need a router to route through straw to create space or a chunky baseboard or something. You can just run all the stuff in that chase and then put whatever interior finish on. You can just sheetrock onto that 2×2 ladder. So if you are doing sheetrock or plaster, it ties into the side face of the post. You end up seeing most of the posts, probably only an inch or two gets covered up.”
Haystack Joinery and Croft both fabricate building components off-site. This allows them to make building components with precision and, once the pieces are delivered to site, the assembly is astoundingly swift. Within a single week the home was framed, sheathed, and insulated. “It’s similar to timber framing,” said Raivo, “You can do jobs that are farther away and you don’t have to commute back and forth. You go up for a week of work and then it’s done.”
We asked Raivo about the wood used in the project, and he described a walk on a 700 acre farm down the road from his home. “There is a lot of crooked wood in this frame that was actually cedar from Misty Brook Farm which is a local farm here,” said Raivo, “I like using curved material in frames and it’s always really hard once you’ve designed something to then go hunt for the right piece of wood. So I try to stockpile curved material for projects like this, and I just have an ongoing relationship with people that I know that have acreage around here and I’ll walk the land and flag stuff and then they’ll cut it for me.”
The panels are the latest iteration in Croft’s ongoing explorations into carbon storage techniques. Andrew pesonally spent countless hours developing the compression system for the panels which uses hydraulic system with an astoundingly low energy input. Andrew showed us an image of an industrial straw compression system used being used by another company. “This piece of equipment you’re looking at here,” said Andrew, “is an absolutely massive industrial piece of equipment. It’s powered by a 792 horsepower diesel power plant that is running 100% of the time. We can compress our stuff with a 12 volt battery. We are using .00003% of the energy to achieve the exact same task that these guys are. That’s the old school approach of industry, right? Let’s throw oil at that problem!”
For the straw used in the panels, Croft employs local growers that are pesticide free and practice no-till agriculture. “We look at how far the material has to travel, how much we process it, and the energy that goes into the manufacturer of prefab panels. Everything is informed by doing things in the most elegant environmentally friendly process we can. And the end result of all this is buildings, which is great! We are a carbon capture company and the byproducts of our carbon capture are housing and food, which is probably the best technology you could ask for.”
Illustration of electrical chase created behind finished wall allowing wiring to run behind timber columns (left). Raivo preparing to raise the curved cedar timber frame bents (center). A Croft compressed straw panel (right).
The timber frame and straw panels both need a crane to lift and drop them into place, so part of the efficiency of the project was planning a sequence of assembly that would allow a single crane and operator to erect the entire structure in a matter of days. “It was such a smooth raising,” said Ravio, “Everything just clicked into place really nicely, and sharing the crane worked out really well. You can kind of see the steps from the photographs. They began by getting the gable ends all the way up. Then on one of the sidewalls they put up the row of lower wall panels. We assembled the two bents and stood them up and installed the timber floor joists for the second floor loft and then dropped in the ridge beans. In between our crane usage, they were proceeding with the fourth wall and installing the upper panels of the side walls.”
1. Straw panels, end walls, and one side wall are erected; 2. Timber bents are dropped into position; 3. Structural ridge beam is lowered into place; 4. Rafters are framed and roof panels are installed.
Raivo and Andrew both recounted the moment that the roofing panels were lowered onto the ridge beam. “There’s a picture of the 36 ft long ridge beam dropping down onto the timber ridges…Everything was just on the money!” said Raivo, “The measurements were exactly right. There was no shimming, everything was just dropped into place and was level. Then it was really amazing watching these pre-built sections of the roof that included both sides of the 22in roof… like this flying upside down V. They were just dangled over and cabled down and they just seated perfectly on the eve. The level of like kind of thought and precision and planning that you really need for a timber frame raising to go well was matched by what Croft was doing. Yeah. Just a well oiled machine.”
“Watching that whole thing come together and the precision and care that he brought to his work and the precision and care that we brought to our work was incredible,” said Andrew, “There were moments like when the roof panels were coming in. There were literally like 20 planes of tolerance that had to be exactly right, and they were!”
Timber frame and straw panels spaced 1/2″ apart.
“This does beg the question,” reflected Andrew, “without that sense of, I mean what we’re talking about here is love and responsibility, without that, does this business function? Could someone else make a building like this with the expectations that currently exist in the world of construction where people will do things quickly and sloppily because that is the cheap way and the materials account for all of those sort of literal corners being cut? You kind of need both, which is a little bit funny. Can someone who is not Raivo reproduce it? I don’t know.”
Andrew described the affordability of the hybrid system and noted that the flexibility of the system is a key selling point.“Most of the things that you can do to make a building affordable happen after the framing and insulation are done. That’s sort of this non-negotiable thing. Framing costs about the same. That vector never really changes much. We just took it and made it not just environmentally friendly, we made it climate positive. We’re storing naturally occurring carbon inside of these buildings and building them in a way that they’re going to last for hundreds of years and then making a space that people will love and that is adaptable to the future.”
“One problem I have with straw bale construction…is that in 50 years when the owner wants to put in a window or to change something, you have this hyper-specialized envelope that, I don’t know, 60 people in the US know how to work with properly. There’s no way of taking Joe Schmo carpenter and unleashing him on that building and saying we want french doors out to a porch right here. That’s one thing about what we do at Croft: it’s future proof. Just go ahead. It’s just a normal building. It’s filled with tons and tons and tons of straw but nothing else changed and it’s super easy to integrate. Take your Skil Saw and cut out the window and then frame it out, all the framing is there…It’s easy for people to understand and therefore it’s easy to sell the system even to the grumpy contractors who don’t care. That’s been one of the most rewarding things: when you get a climate denier who is just like, ‘This is great and the price is right. Thanks!’”
As with any building project, the measure of success is about more than the resulting material artifact. We were inspired and delighted by Andrew’s and Raivo’s enthusiasm about craft, spirit of experimentation, commitment to environmental justice, and the human relationships that they described growing though the design/build process. “I really love the idea that there is the building and then there’s what the building symbolizes,” said Andrew, “[as builders] we are literally leaning on each other’s sensitivity. We care for each other and what the other person is doing and there’s a loving environment…wouldn’t that be great if that’s just the way work was?”
Straw panel end and side walls with assembled timber framing.
Andrew William Frederick is the founder and principal designer at Croft, a company making carbon capture, factory crafted buildings. With a focus on pragmatic, low-tech, deployable solutions, Andrew is dedicated to seeing Croft rewire the construction industry with faster delivery, lower cost, and more climate-friendly solutions for all. He has virtually no qualification for this role other than being raised by people who forgot to point out that some things are impossible.
Raivo Vihman founded Haystack Joinery, a design-build studio with a focus on sculptural timber framing, in 2008 after moving back to Maine at the end of four years of itinerant journey work. Before that, he built his first small timber framed cabin on some land in Freedom that many years later he found his way back to. And before that, as a boy, he visited an open-air museum in Estonia that bestowed a vision of an organic architecture which seemed to sprout directly from the land, and which continues to guide his work today.
