We’ve all heard of “farm-to-table” in the context of our food, but what about “farm-to-shelter” in the context of our homes? As we try to become more conscious about the food we eat and the clothes we wear, we must also consider the materials we use when constructing our homes. While many acknowledge the need for better materials in buildings, very few modern day designers have successfully completed a project that consists of healthy and sustainable materials from top to bottom.
Andrew Linn and his partner Jack Becker of bld.us are doing just that. They started by building their own sustainable (and compostable) structure – the Grass House – located in Washington, DC. This project holds a special place in our hearts, because we worked as the sustainability consultants for the house. In this episode, Robb talks with Andrew about the materials he employs in his projects, and their positive sustainability and health impacts.
Episode Guest: Andrew Linn, bld.us
Andrew Linn founded bld.us with Jack Becker in Washington, DC in 2013. bld.us integrates traditional construction methods with new technologies and organic materials ideally suited to the Mid-Atlantic region to create an architecture of accommodation. Based in Historic Anacostia, bld.us seeks opportunities in economies–of scale, of scope, of density, of means, and of materials. Andrew has 16 years of experience in the Architecture industry, and has been a lecturer at University of Maryland’s School of Architecture, Planning & Preservation since 2017.
Episode Information & Resources
- Grass House Case Study
- bld.us website
- Tour the Grass House
- Building materials mentioned throughout episode:
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About Buildings and Beyond
Buildings and Beyond is a production of Steven Winter Associates. We provide energy, green building, and accessibility consulting services to improve the built environment. For more information, visit www.swinter.com.
Welcome to buildings and beyond
The podcast that explores how we can create a more sustainable built environment
By focusing on efficiency, accessibility, and health.
I’m Rob Aldrich.
And I’m Kelly Westby.
In this episode, I spoke with Andrew Linn, who is an architect based in Washington, DC. We talked about sustainable materials and products he uses quite a bit. And we talk specifically about the Grass House project, which is actually his office in Washington. As you’ll hear Andrew is really a believer in many of the products he uses, which is very cool. We often try to avoid too much discussion of specific products on this podcast, but that is not the case in this episode. A quick disclaimer, this isn’t necessarily an endorsement by Steven winter associates, these are Andrew’s opinions, but I really enjoyed talking with him and I learned quite a bit. We’ll provide some links in the show notes for folks who want to dig deeper. I also wanted to mention a couple of podcasts we had – a two-parter we had back in the summer of 2019, where we interviewed Charlie Stevenson. We talked more in depth about sustainable materials. So if that’s an interest, you might want to check those out. Here’s my conversation with Andrew.
I have always wanted to be an architect. I grew up wanting to be an architect and I worked for some of the best offices I could imagine working for when I was in school. And when I left school, I realized that even those offices were hampered by the material pallets that they were able to work with. And so my college best friend and I set out to find a healthy building material palette. So we moved to DC where we felt like there was already an appreciation for the landscape and for the materials that come from the landscape, there was also and is in DC, a an awareness of an attention to code and regulations and designing for those most in need. So we felt like DC was the place to to build our practice. So we moved to DC, founded, bld.us and began looking at the materials that were available to us, although not always the most popular, that were the healthiest for the environment and for the users of the buildings
I just realized your URL, your website, the URL is great. It’s bld.us. And you, you say ‘build us,’ that’s how you say it.
Yup, like a proper Roman name,
BLD is your, is the initials of your firm? Is that isn’t that right?
We began as Becker Linn design, my name is Andrew Linn and my partner is Jack Becker. So we began as Becker Linn designed, but we’ve begun just referring to ourselves as bld.us Both in website and a name because we like the ethos that it promotes. We’re about building community. We’re about building using American domestically sourced products. So bld.us is a really nice idea to strive for.
I see. Very easy to remember URL. So when we were talking about doing this podcast a week or two ago, you used a term that I don’t know that I’d ever heard before, which was farm to shelter. I’ll farm to table. This is farm to shelter. Is that something that you coined that something you’ve been thinking about for awhile?
I hope I haven’t coined it, but I haven’t heard it much. So it wouldn’t surprise me if that’s the case. You know, half of the TV that I find that’s available has something to do with cooking. And even if it’s not a cooking show, they find a way to bring it in. And people are very interested in where their food is coming from, how it’s getting to them, who’s taking it out of the ground and how they’re being compensated for taking it out of the ground. That same attention and awareness has gone into the clothing that we drape around ourselves. And it only seems logical that that type of of awareness would also extend into the built environment. So there are different ways of tracking the health of a building like the living, building challenge and like the well rating systems. But they’re very challenging. We’ve tried to work within those requirements and in DC middle-class housing, it’s really not feasible without subsidy of some sort. So we’ve been looking for a farm to shelter, material palette that is affordable to the middle class that doesn’t require a whole bunch of soft costs, sunk into applying for different ratings and different certification systems. And we’re just looking to bring affordable, healthy housing to the people that need it, and who are reliant on Home Depot and Lowe’s. And nothing Home Depot and Lowe’s, they are getting with the program almost quicker than many of our clients.
Yeah, it was kind of interesting for me to hear that, that term, just using local sustainable materials, the farm to shelter, we’ve all heard farm to table. It was, it was a pretty clever term. I thought. So the project that we started talking with you about, and Steven winter associates worked with you a little bit on it is is called grass house. And is it your office? Is it your primary workspace studio space?
Yes, it is.
Okay. And it’s, it’s an outbuilding. Could you describe what it is, where it is?
Yeah, so the grass house is basically a compostable accessory structure built behind an 1892 queen Anne Victorian house at the foot of the Frederick Douglas House in the Anacostia historic district. So this is East of the Anacostia river. It’s the only historic district in ward seven and eight of DC. Even though there are a few others that deserve to be historic districts. But that’s where we work from. We do a lot of work there. It is a place that has a pretty diverse, eclectic set of styles within its historic district. But that’s within a time span of about the 1880s to the 1910s. So we’re working within that vernacular and trying to design and build a building that is as healthy as possible. We ended up with a LEED platinum rating on it and is as sort of affordable or at least speaks to different affordable moves so that we could use it as a showcase and bring in different potential clients and different people who were interested in it, different neighbors so that they could see possibilities. So we have a fun stair. We have a fun window detail, we have a fun bathroom countertop detail. And we usually tell our clients that they could pick one or two of those details to really play with in their house. But in addition, where we’re trying to showcase as many different, healthy building materials and natural finishes as possible.
Yeah. So folks can go to BLD dot U.S. And there are pictures there, which are, which is pretty cool. The first thing I noticed when I looked at the pictures was this is a very small building. What was it like a 250 square foot footprint or something like that?
Correct. And for that reason, we went down and we dug out a basement, which in general, we’re not typically fond of, but we wanted to maximize the square footage that we were able to have, but we wanted to keep the overall massing as small as we could.
So you used a term a couple of minutes ago. I think you said it’s a compostable structure, which I understand, but does that term have great optics? The first thought is, Hmm, it’s gonna rot quickly. Do you run into resistance with that, with that phrasing? Does it test well?
I mean, the people that I’m quote unquote testing it with are very into the idea because we quickly explain that the techniques that you use to build the building require you know, attention to detail and you pull the wood or compostable material up off the ground a little bit, and you protect it with big overhanging eaves and use a nice breathable rain screen system so that the whole building can breath. When you approach a building trying to find the places where it will fail which are almost always related to water or moisture in some way, when you approach the design with that as your priority, the fact that the materials that you produce it with are compostable, it isn’t an issue. So at the grass house, we have slate and copper roof, you know, you’re not going to find a more durable roof than ours. We have big overhanging eaves. We have a breathable exterior cladding system. We have a concrete base that comes up two and sometimes three feet up, up off the ground, so that all of our bamboo and wood framing system is away from rain. And we collect all the water that you know, falls off of our roof and we harvest it in a cistern. So when you have control over the water, or at least when you have respect for the water that is trying to degrade your building, you’re able to make the building out of healthier materials.
So you mentioned bamboo, and that’s where the name grass house comes from. I believe, maybe I assumed that, but I believe that’s where that came from. Can you talk about the wall system a little bit?
Yes. I’d love to. I love BamCore. I’m one of their biggest fans. BamCore is essentially the mass grass to mass timber. So it is a lighter weight version of the same principles that are being applied in mass timber. And as many of us have come to realize, mass timber doesn’t have great implications for the single family and low rise residential markets, but BamCore does. And that’s exactly where BamCore is at its best. So Bamcore has been refining this panel system, and what the panels allow us to do is build without studs. And that gives us continuous insulation cavities, which gives us incredibly high performing wall systems that allow us to contain either the hot or the cold air that we’re creating. So we’re able to input very little energy into heating or cooling a BamCore house. You’re able to reach passive standards almost effortlessly because you’re removing all of the standard thermal bridges which is what exterior insulation envelopes attempt to do, And do, but bamcore does it in a, in a more integral more high performing way.
I don’t have any firsthand experience with this product, but it’s a panelized approach. So like all the walls come on a truck or a pallet, or a couple of pallets, all cut in the right dimensions and labeled, and you piece it together on site pretty quickly, I imagine?
Very quickly and a real benefit of bamcore over other systems like sip systems or pre-manufactured systems is that these are panels that you and I could lift. And I don’t know what you look like, and I know that you could and I could lift them because it’s essentially a piece of drywall. So you’re able to remove drywall, you’re able to remove studs, you’re able to remove OSB sheathing, and you have these packets of precut wall panel delivered to the site. You pop them up off the truck and up onto the site almost like an Ikea structure. They used to have you screw them in, and now you’re just nailing them in. So very simple and very simple to take apart, you know, someday in the future. These panels are unbelievably durable. They they’re made from bamboo, which is in some cases as strong as, you know, different types of metal, stronger than different types of metal. And that allows for the panels to have sheer strength to them. They’re Bulletproof. They perform extremely well in hurricanes. The makeup of these walls and these wall sections allows you to have thinner or larger wall cavities. So these, these walls are just as high performing and cost-saving as they in Florida as they are in Vermont.
We can put some links in the show notes, because, I mean, I talked to you, you described the system a little bit, but I didn’t get a full picture until I looked at some pictures and as the podcast is only audio, we can certainly link to it, because it was pretty cool. I didn’t get a full picture of how all the pieces went together until I went to the website. And it seems like a lot less material. Cause my understanding is they are trying to grow bamboo domestically, but they are not yet. So a lot of this, a lot of the material gets shipped a long way, but there’s much, much less material. It looks like. Is that a big piece that goes into it being a carbon winner?
It’s a huge piece. There’s less material, there’s less material waste, and bamboo is the best carbon sequestering organic material that exists. So the more bamboo we can use, the better. Bamboo, unlike wood retains the carbon that it sequesters even while it’s being harvested, because it gets clipped like grass, not mowed, not clear cut, but clipped. And so a clean bamboo Grove is healthier and taking out calms that are ready to be harvested, makes very clean bamboo Grove. So the more bamboo we can use, the more bamboo we can plant and store in the built environment the, the more carbon we’re going to be able to sequester. So even though right now bamcore is bringing bamboo in from places like central America and South America, which are still relatively close given that we get doug fir from Washington state or Oregon. They’re working on creating a domestic supply of bamboo, but there’s already so much bamboo around the world that we just need to find more ways to use it in the built environment
And insulation. You can use any insulation with this panel system, but you went with wool, which again, I don’t have any firsthand experience with. Not mineral wool, but like sheep’s wool, is that, is this the first time you’d used it? Or is this one of your kind of go-to materials?
It has become a go-to material since working on the grass house, because we, we love working with it so much. It, it doesn’t out perform other materials more than the other healthy materials that we’re looking at. So bamcore is exceptional compared to wood stud framing, wool is exceptional compared to fiberglass, but being able to touch wool, it feels so good. It feels good to stuff it in the house. It feels good to know that you can breathe it, that sheep’s wool absorbs VOC that are in the air, but does not produce any, it expands over time. It wants to return to the state that it was in when it was on the sheep. So those cavities, you know, are going to be full and they’re not going to have any sagging spaces.
Oh it expands over time?
It expands over time. Every piece of wool that comes off of a sheep, it grows in a certain way on that sheep. And then we pack it into a bag and we send it to a construction site and then we pack it into a wall cavity and it wants to return to that, the shape that it was in when it was on the sheep.
Okay. Kind of elastic. I mean, I certainly have wool clothes that do not expand over time. They do the opposite, but it’s a different, different thing we’re talking about.
Yeah. That wool has been processed and it’s been cleaned in a different way and it’s been strung out into yarn and then it’s been, you know, sewn into a textile or a fabric. And here it’s, it’s, it’s being cleaned and treated with an anti pesticide in as simple and sort of light of a way as possible, almost like when you’re making a pastry and you’re trying to handle the dough as little as possible so that you can keep the air in the dough that that’s the way that they, they treat this wool.
And here again, it’s, I don’t have any experience with it, but it seems that raising livestock for an insulation material would be pretty carbon intensive, but I assume you or somebody has crunched the numbers and found otherwise, is that accurate?
That’s well, that’s accurate when you think that the alternatives are recycled denim that has already gone through some pretty awful, you know pieces of life or, or not recycled and just denim, which will sag in the wall, cavities you know, fiberglass is not produced in a great way, mineral wool, which is invaluable in cities and certain applications, has a pretty bad reputation in the communities that it’s produced in. So it’s not like there are great alternatives out there. There are certainly nice ways of raising sheep that, that are good to the sheep, good to the ground. And, and in some areas that we’re working in people are advocating for livestock rather than maintenance of grounds, large-scale grounds using lawn mowers and things like that. So you know, there are, there are trade-offs but the, the way that the wool performs is exceptional, the material that I could see that could enhance the use of wool would be mycelium.
And I know that Ecovative is working on, and has always thought about different ways that they could use their mycelium product, which is the roots of mushrooms in the built environment, because then we could really be growing our insulation. But sheep’s wool is an incredible performer. There’s an abundance of it right now. A lot of the wool that’s produced is not acceptable to textile manufacturers, and there isn’t really a use for it. There isn’t a market for secondhand or third hand wool in the U S yet, but if people start asking for it, then I think it would be a great solution to stuff that into wall cavities, bamcore wall cavities.
Cool. So in the roof, you had to go more conventional, I think you said you had to use foam, is that right?
We are insulating our roof with foam. Yes. And that’s so that we can have a pretty small roof cavity. We had a 20 foot height maximum because we’re an alley house and we wanted to fit two stories in. so it’s a, it’s a relatively tight insulated cavity, but it allowed us by staying tight there, it allowed us to vent and insulate on the top above the decking, but below the actual roofing. So we were roofing with slate and that sits on top of a black locust sort of raft of eaves and timber members that hold pieces of exterior insulation. And that sits on top of this unvented roof cavity.
So, I mean, is there any reason other than kind of R-value per inch? Is there any reason you could not use wool in the roof?
No. Wool would be exceptional and they’re making wool in bats. They’re making wool as loose fill, so it can be sprayed in blown in which would be a perfect application for a roof for an attic. I would love to only use wool and cork and my mycelium as my installation materials for the rest of my career. And I think it’s amazing that we could be you know, having house stuffings with our clients and their families with sheep’s wool in the same way that communities used to do roof raisings or things like that, just so that they know that what used to be the toxic poisonous phase of the construction period when you’re stuffing your walls with fiberglass or foam is now a thing that the whole family can participate in because it’s so healthy.
We’ll see if we get any comments about calling fiberglass toxic.
Well, it is not something that anyone wants to breathe in. That’s for sure. And the fact pregnant women, aren’t supposed to be around construction sites during certain phases. Like we would like for our compostable houses to be able to be built with, with pregnant women as their GCs, you know, it’s unacceptable for, for our buildings to be poisonous for a certain phase. And to assume that they’re going to just air out, that’s how, that’s, how we feel about that.
So talk about the siding a little bit, and again, I encourage people to go, go to BLD.Us, to take, take a look at some pictures. The siding is pretty cool and the whole siding assembly.
Thanks. The cladding is produced by Resawn timber company. They are a very cool Pennsylvania based company. That’s doing research into different methods of finishing wood. Sometimes the charred wood using the Japanese technique. Sometimes they’re mixing that with certain stains and oils and finishes. They’re using a lot of wire brushing and they have these really cool assembly lines that are sort of pizza pizza oven style, but they, you know char in two different temperatures and wire brush into and staying in one and they’re able to get these pretty nice finishes. So we, we have a very simple product from them. It’s Atlantic Cedar. We worked with them to source Atlantic white Cedar, which they hadn’t done before. It’s it was considered sort of too shabby before. And now it seems like there’s a demand on their website for Atlantic Cedar, because it’s more local than red Cedar, or even the Cyprus that comes from the Southeast. So we have a really nice black Cedar siding, and that is sitting on furring strips that are at diagonals because our cladding is at vertical. So we wanted to pull our cladding off of the main building structure using the fern strips. And, and those diagonal furring strips are crossing at our corners. So sort of like how stone is coined. We’re pointing our furring strips at the corner.
Cool. And yeah, you used a lot of other local materials, I think mainly wood for interior finishes? And I think there was a bench detail that looked pretty cool on the stairway, like you mentioned, was, was a very cool design element. How much of it came from you deliberately going out to find something to do what you wanted to do and how much of it was, Hey, I have a great source for black locust or Willow or Walnut, or how did, how did, how did those pieces come together?
So we’re trying to put together the ideal healthy building palette for the mid Atlantic and certain of these materials just perform better in certain applications than others. And that’s the case, whether it’s bamboo or Willow or wood and the different subspecies of each of those. So Willow is great for interior guardrails and screens. And so that’s why we wanted to use Willow for our three different interior guardrails. And we took different strategies as to how those were designed and built so that we could learn ourselves. And so that we could show clients what’s possible. We knew that on our exterior, we wanted to use black locus because it is a very local, very abundant wood that performs just as well, if not better than mahogany and epay and all these other tropical species. So if we’re going to be importing bamboo, we want to do it for the right reasons. If we don’t need to import wood, because we have this other tree that’s everywhere and just not use that much, we’re going to use that. So all of our exterior wood, all the big members in the roof and the bench and the sort of pergola over the front door, that’s all black locust. And we loved working with it. It’s kind of a fussy wood. It, it moves and it, it turns a little bit, but if you can sort of brace it with itself. So we’re kind of making little weaves out of it, then it locks into place. And it just it’s, it, it wears over time really well. It doesn’t, it’s not impacted by water. And, and we expect it to be just fine for 50 years or so. On the interior we’re finding uses for a few different trees that we knew we needed to take down in the neighborhoods. So seven blocks away from the grass house. There were a few trees hanging over a commercially rented parking lot where food trucks are parked. And those trees were only being held up by some grapevines that were like huge and, and holding them back. And so we felt those trees, one was a Mulberry and one was a Walnut, and we use the Mulberry for all of our handrails and on the stairs and a few other interior details. And we use the Walnut for our beautiful stair slabs. The Walnut was basically purple. So it was, it was great. And we used one of its big branches as our handrail up on the second floor. And we use some leftover wood for the bathroom countertop and the toilet seat, and we really, it, we used it like a Buffalo.
Cool. Yeah. So I’m just thinking about all, about the panelization for the walls, for the main, you know, the systems in the home. And I think, you know, in talking with you earlier, panelization is a a pretty strong interest. On the other end of the spectrum, though, it’s just kind of this custom details using local trees, which it’s kind of entirely different than standardization and panelization, but they seem pretty complimentary. Can you talk about your goals? How far you want to panelize versus customized?
Yes. And it’s a great question. And you can kind of think of it like the Tesla cyber truck, which is, you know, rolling off the factory assembly line with as few pieces as possible versus a really high end sports car that has hand detailed hand on details, handmade details. We don’t, and bamcore doesn’t want to take anyone out of business or, or take laborers off the site. I should say we don’t want to remove work and remove workers. We want to be able to build more affordable housing because there’s a shortage of affordable housing in a healthier way. And so if we can redirect the labors of the workers away from places like painting walls, and we know that painters have higher rates of cancer because they’re interacting with paint all day long. If we can take them away from painting because we’re charring and finding other ways to finish our interior wood panels instead of drywall then we can redirect them and have them working on some of these nice handcrafted details using wood. And we can have more of a carpenter like industry like we used to have a hundred years ago when chestnuts were popular and when houses were hand-built and when craftsmanship was appreciated by people. And you can see it in the food industry that craftsmanship and quality and materiality has become very important so much so that these companies like McDonald’s and, you know, the, the big, fast food chains are having to become their version of farm to table. So we’re hoping that construction can tend away from the materials that we are left with after world war two and tend towards the materials that make sense for the health of the inhabitants and the health of the planet.
So if we talk again in five or 10 years, what do you think we’ll be talking about? So what systems here do you think will become standardized? What new do you think we’ll start seeing more and more of down the pipe a few years?
Yeah. So I think that bamcore is ideally suited for producing housing in large quantity. So, you know, ideally it’s not subdivision tracks, ideally it’s denser housing than that, so that we’re not having to eat up the entire landscape, but if it is subdivision tracks, if a developer is going to do that, then I hope that they’re building with bamcore. Not because they want to be green, but because they know that they can market the energy savings to their customers. And that will allow that and an acceptance in cities of bamcore in the low rise residential sector, which I think will come more naturally, I hope will lead to bamcore having a real impact in bamboo having a real impact on the framing systems of of low rise residential all across the country. I think sheep’s wool is going to be sold on the shelves of one of these big hardware stores in the next five years, if not, probably much sooner than that. I think cork cladding has exceptional potential right now. There’s a need to put cork into use across the world because there’s all these cork plantations around the Mediterranean that are no longer supplying wine bottles with cork because they’ve turned to metal and cork is a fantastic exterior insulation material, which is now required by code and can double as a cladding system. So bark is a, is another great exterior cladding material. But bark has a little more boutique, a little a little less performative in that it’s not insulating, and cork is, is just exceptional at it. So I hope that the popularity of cork as an insulative material as a cladding material, as a flooring material will start to come back because it was very popular in the U S before world war II. And before the foam industries were required by the needs of a war. So yeah and if those, if those three major products, bamboo, wool and cork are finding their way into more intelligent uses of wood, then I think we have a really a really bright material palette for everyone to get their hands on.
Well, thank you. Thank you, this has been a great conversation.
Of course, thanks for having me,
You for listening and thanks to Andrew. Check out the show notes for links to some of the info we talked about buildings and beyond is produced by Steven winter associates. We’re focused on making buildings better, more sustainable, more healthy, also accessibility efficiency, resiliency, comfort. Check us out @ swinter.com. swinter.com/podcast is where the show notes live and check out our careers page. If you’re looking for opportunities, we have positions posted for all of our offices, Boston, Connecticut, Manhattan, and Washington, DC. Thanks again to Andrew and thanks to the podcast team here at SWA Jayd Alvarez, Dylan Martello, Heather Breslin, Alex Mirabile, Kelly Westby, and I’m Robb Aldrich. Thanks.