Small house solar: full details of the Matchbox system

Solar technology is awesome, but it’s also awesomely confusing. Between batteries and panels and chargers and inverters and controllers and more, figuring out a working solar system is a daunting task, especially when space is at a premium. A few weeks back, the Matchbox got solar, and so—in the hopes it’ll help someone looking to unplug a small house of their own—here’s the full scoop on my working solar set-up.

To begin, this system was not cheap. Affordability was always a secondary concern for the Matchbox (trumped by reliability and livability), so at $8,400, these components may be out of the price range of some. It can be had for cheaper—indeed, I spent a little extra to order all the parts together, and a lot extra on a pre-wired FlexPower unit (which contains the charger, inverter, controller, and more), rather than risk death by electric trying to get those individual components wired together.

It also wasn’t easy. Even with a pre-wired unit, the installation was way complicated. I was fortunate to get a ton of help from a great and electrically-inclined friend, but getting everything hooked up took the two of us about four full days. For a novice, a professional installer may be necessary—and come at a higher price. (Despite the struggle, learning the ins and outs of the system was a ton of fun, so perhaps this would be a good week-long project for a persistent DIYer.)

Not cheap, not easy, but it does work. Well. Or at least, sort of. I’ve been running the system for a few weeks now and it does just great—even with my AC refrigerator and non-LED lighting, it drains less than 15% of the battery bank during an average day of use, and that’s without recharging. The thing is, the Matchbox currently rests under a pretty thick tree canopy, blocking all but the most indirect sun from touching the four panels on the roof. As such, it’s not really recharging—and won’t be able to until it moves to sunnier pastures—but once it can charge up, it should top the battery bank off fairly quickly.

So, those are the caveats. These are the details.

  1. The panels: 4 SolarWorld SunModule 315W/24V monocrystalline panelsYour basic 315W panels. The Matchbox roof (and most other roughly 8′ x 20′ flat or slightly pitched roofs) can fit four, for a total 1.3kW array.
  2. The batteries: 4 Trojan Reliant L16-AGM 6V 370AH sealed batteries ($499 each, $1,996 total). Safe for small interiors, compact, and capable of storing 1,480 amp-hours (roughly 9kWh). Note that these particular batteries are pending recall for a non-urgent sealing issue, so perhaps the Trojan Reliant’s aren’t, well, all that reliant.
  3. The unit: FlexPower ONE VFX3524 pre-wired system, including AC/DC boxes, inverter/charger, FLEXmax charge controller, and MATE3 hub ($4,035 total). Perhaps overkill for such a small home, but magic nonetheless. Capable of charging batteries from the sun, inverting DC to AC and AC to DC, charging batteries from a hook-up or generator, and keeping everything running and monitored and safe.
  4. The odds and ends: connector cables (2), connector key (1), combiner box (1), locknuts (2), breakers (2), rails (4), end-clamps (2) and mid-clamps (1), l-foots (2), battery connectors (3), and battery cables (1), all totaling $507. Another $520 for Massachusetts-to-DC shipping, and about $100 in tools (crimpers, wire strippers) and parts (wire, ring connectors) from the hardware store.

I got all this from the folks up at altE in Boxborough, MA, who were great in helping me figure out what I needed. They weren’t the cheapest, and this is in no way a paid referral, but feel free to use my sales order (SO-127929) as a starting point if it helps—or, y’know, comparing prices of the above links across the internet for the best deal.

So, those are the parts, but in such a small house, where do they go? Well the panels, obviously, go on the roof, and take up most of the seating space up there (though this amazingly entertaining strength-testing video suggests they’re more than sturdy enough to sit on). The FlexPower unit goes where the electric fireplace used to go, taking up about 33″ x 20″ of wall space and jutting out about 13″ from its mounting plate. The batteries sit on the floor underneath, occupying about four square feet in the corner. And the circuit breakers go in a back bumpout, though these could easily be installed right next to the FlexPower unit. Altogether, the interior solar bits and pieces take up about as much space as a small corner desk might (a really small corner desk).

It’s worth noting that the batteries and inverter/charger will give off heat, so best to keep them away from combustibles and be mindful of that heat during the warmer months. They’re also heavy. The main unit weighs 110 pounds, and each battery about 115, so assuming those are all tucked away in one corner of the house, that’s about 600 pounds shoved in one corner of a small, trailer-supported house. Considering another 200 pounds for the four panels (50 pounds each), a solar system of this size will add nearly 800 pounds to a tiny house—not an issue for those built on 14,000 GVWR trailers, but definitely a concern for a single-axle model.

And, finally, your mileage wattage may vary. The Matchbox system is a good system for the Matchbox—or at least, it’s been doing okay so far—but solar is a big investment. Let me know if you have questions in the comments below, and I’ll let you know how the system does as we move into the hotter (and then colder) months, but whatever you do, get a second opinion before dropping thousands of dollars on a tiny house solar system.

More pictures to come, but for now here's another look at the unit and batteries.

More pictures to come, but for now here’s another look at the unit and batteries.

A beginner’s guide to downsizing, part 4: Books and the rest

We keep most junk around for economic reasons: because we think we’ll use itbecause we think we’ll need itbecause we can’t accept a sunk cost or because we can afford to buy knick-knacks of no value. The last breed of junk, however, isn’t economic; it’s emotional.

#5: Books (stuff that you’ve [maybe] read once and will [probably] never read again)

I should begin by noting that I am nothing if not a bibliophile, a lover of literature and the limitless knowledge and entertainment books contain. But loving literature is not the same as loving books.

I have great friends with lovely libraries, cabinets and cases of texts and tomes, paperbacks and publications, hundreds and hundreds of bindings containing thousands and thousands of pages. It’s beautiful wall art.

But is it functional? Hardly. Think of all the books you’ve ever read. If you have a library, think of how many books you own. Now think of how many of those books you’ve read a second time. Some? A third time. A few? A fourth time. Maybe two, one, zero? Practically, personal libraries are overwhelmingly underused: a book purchased, read, and then shelved, never to be opened again. With over 130 million different titles in existence, the reader rarely returns to her collection. Rather, she adds to it—buy, read, shelf, repeat—and the library grows.

Many books, lots of space.


So what’s the harm? Space, for one—libraries take up a lot of room and are a pain to move. Finances—buying books costs money. And then there’s the environmental cost: books are, well, made from trees, and every new copy of a book requires new pages, new trees. My simple back-of-the-napkin estimate of Dickens’s A Tale of Two Cities, for instance (200 million copies at an average of 500 pages each, with a single sixty-foot pine tree yielding about 80,000 pages), has required nearly 1.3 million trees to produce over its long print-cycle—about 3% of the Amazon’s (the forest, not the retailer) present inventory. And remember, that’s just the impact of one (very high-selling) book.

But space and money and planet aside, perhaps the best argument for ditching the library is sharing. As with just-in-case junk (for what is a library but just-in-case-I-want-to-read-this-later junk?), everything we have is something someone else can’t have. When we hoard five hundred books just in case we want to reread five, we’re keeping 495 books from our community, 495 books that can be read not later, but now—right now. And let’s face it: if we care about a book enough to keep it, isn’t it inherently something we think others deserve to experience as well?

But how do we go about reading without amassing a library? Simple. We begin by donating our books—all those but the few we really, really, really believe we’ll read again—to real libraries, public libraries, libraries with free and open access to all. Or we build a little free library in our neighborhood and stock it with our best. Or we pass on our collection to a used books store, perhaps even sell them on Amazon (the retailer, not the forest) for a fair price. We keep the revolving door revolving.

Then, we get a library card. We check books out and check them back in, or we buy new books and sell them back when we’re done. Maybe we get an e-reader. Me, I’m partial to the Kindle Paperwhite (though I trust they’re all very good), finding it to offer quite a few benefits over the paper book:

  • It’s light. At under 8 ounces, an e-reader weighs half of an average paperback, and that weight doesn’t change for the epic novels. Infinite Jest and Cannery Row not only weigh the same, they weigh the same together—8 ounces on a Kindle, 2 pounds in hand. For travelers, e-readers are phenomenal; one can easily pack 100 books for a multi-month excursion, and stuff the whole collection right into their back pocket.
  • It’s … light. Speaking just for the Paperwhite here, it’s an absolute pleasure to read in the dark. With a soft, adjustable backlight that’s easy on the eyes, reading lamps, flashlights, and strained lenses are a thing of the past.
  • Books are affordable and available for all. With thousands of titles in the public domain—and many more free to download if you know where to look—e-readers have the potential to truly close the literary gap between the advantaged and the disadvantaged. Growing up with neither the money for books nor someone to take me to the library regularly, it’s heartening to see such open access to literature growing and evolving, but it depends on the support of all of us to continue doing so.


Of course, I’ve heard the arguments against them—but I love the feel of a book!, they smell so good!, or the entitled and illogical ramblings of Jonathan Franzen—and for a while, I believed them too (maybe not the Franzen bit). But the truth is, first you try an e-reader, then you get used to an e-reader, and then you prefer an e-reader, and the bookworm inside of you thanks you for it. The minimalist in you does too.

Many books, little space.

#6: Sentimental junk (stuff that we may or may not hold dear)

I won’t ridicule sentimental junk as I have junk’s other five forms, for our sentimental items are often those we’re most sensitive about. We give them value that transcends currency; often, we consider them irreplaceable. These treasured bits of ​our very selves adorn our home and warm our hearts—the very type of thing I’ve advocated for keeping around in the past—so I want to be clear that what I’m talking about here is not the urn or the photo album, nor the old rocking chair passed down through the generations. Sure, these are sentimental, but they are not sentimental junk.

Sentimental junk are those items we keep because we feel they should have value. Old holiday cards with more matter than message, ticket stubs we plan to scrapbook one day but never do, letters from lovers long gone, a final draft of a senior thesis or a diploma itself. In my own downsizing journey, these were the most difficult items to part with. But after the hesitance, recycling my diplomas and burning old correspondence felt cathartic, freeing, leaving my past alive in the only place it really exists and the only place it can be truly treasured: my memories.

And then, of course, there’s digitization. Yes, we can burn our letters and toss our photo albums and discard our physical encumbrances, but that needn’t be our only option. For we live in the digital age, an age of uploading and archiving, an age when the contents of a shoebox or a trunk can be preserved on a chip smaller than a fingernail. Perhaps flipping through digital albums isn’t quite the same as passing an afternoon in the attic perusing old photobooks, but hey: at least you don’t need an attic.

This post is the fourth of a series on living simply. More to come soon.
Cross-posted at Adventures in Simplicity.

Life with a loft

The Matchbox, like nearly all tiny homes, saves on space with a sleeping loft: forty square feet elevated roughly seventy-eight inches off the ground, just enough room for a mattress and its occupant(s). Having spent my fair share of nights in the Matchbox’s queen-size loft, let’s take a look at the the good, the bad, and the ugly of loft living, from safety to sustainability to sex—and everything in between.

The Matchbox and its spacious loft, with the skylight adding a feeling of great openness.

To begin, lofts are cozy—like, really cozy. When designed right, with ample headroom and a generous skylight and soft linens, the loft is a lovely place to read, rest, or watch the clouds drift by. A hideaway flatscreen (like the one featured in the Matchbox) can transform the space into a tiny cinema, and the removable skylight provides quick egress to the roof—important for safety, but also a lovely place to sit and contemplate on those warmer summer nights.

The loft does great in the cold as well. Because hot air rises, a loft will always be the warmest place in a tiny house, so running the fireplace a short time before bed is typically enough to keep one comfortable for hours: no need to use electricity the whole night through. And when things get a tad too toasty, easy access to the skylight allows for heat to be vented up and away at will.

Then, of course, there’s the space savings: forty square feet elevated means forty square feet of surplus down below, or forty square feet less altogether, allowing for a tinier, simpler, cheaper, greener home—though one not without a few admittable tradeoffs.

Brian designed Minim House without a loft, as he found the elevated bed useful only “if you’re young, don’t drink much, can handle rain noise, and don’t get too creative during sexytime.” Some fair and very valid points: loft ladders are more physically taxing then simply rolling into bed, for starters. When I had surgery last year, I had to spend a week away from the Matchbox because I couldn’t make it up the loft, and after a long run or a full day of rock climbing, lifting myself into bed is something of a chore.

They also, indeed, require more sobriety to climb. I’m a responsible drinker, so I’ve yet to find myself in a serious liquor-versus-ladder showdown, but loft safety more broadly is a serious concern. In testing a (failed) method of securing my ladder to the loft this winter, I fell off it twice while climbing, fortunately making it back to my feet with only a few bruises. And while my memory foam mattress and calm sleep demeanor protect me from rolling right off the bed while asleep, most tiny house lofts do lack railings, and thus are a terribly dangerous idea for he-who-tosses-and-turns or she-who-sleepwalks.

To Brian’s third concern—rain noise—I can’t say I ever recall being bothered by the crash of rainfall, but perhaps my fondness for nature’s dearer sounds leaves me biased. I won’t, however, rebut Brian’s final claim: a loft does, indisputably, limit your intimacy options.

I’ll admit that in designing my loft and choosing its height, “maneuverability” played a key role. I’m quite satisfied with the way the loft turned out; I find that between the queen-size mattress, the flat ceiling, and the raised skylight, there’s more than enough space for a roomy romp. But there are limits, of course: prohibited positions and the occasional bumping of the head and a mild awkwardness that demands that one, well, have a little familiarity and shared sense of humor with one’s loft guest(s). It’s a tradeoff, sure, but one with a simple solution, if need be: just take it downstairs.

Getting downstairs is, in itself, something worth noting. Life with a loft means no more rolling out of bed. Waking up and descending into productivity becomes a careful, deliberate action, and when really tired, it truly is the last thing you want to do—when the loft is nice and warm and the space below cold and unforgiving, even more so.

***

So there’s the good: lofts are simple and cozy, they take advantage of thermodynamics to save energy, they provide easy access for escape (essential or otherwise), they save considerable space, and though the athleticism required to climb in and out of one daily is sometimes a pain, there’s something to be said for a loft doing its small part in keeping you young, both at heart and in body (the edge of the loft also serves as a perfect pull-up bar, I should add).

And then the bad: they’re not the safest sleeping solution (a fall or two is to be expected), and they are a bit of work to climb down from after a long night of slumber. They limit sex—not prohibitively so, not at all with a little creativity, a well-placed skylight, or a descent downstairs—but they do, incontrovertibly, make some of its manifestations a touch inconvenient (I won’t argue that Bob Dylan’s “Lay, Lady, Lay” wouldn’t have quite the same ring to it were that big brass bed switched out for a tiny house loft). And they do bite a chunk out of ceiling height in the bathroom (atop which they’re usually placed), perhaps making it difficult for the taller among us to shampoo and lather without bumping a hand or elbow against the bottom of the loft.

Finally, I haven’t forgotten the ugly. Up to this point, I’ve been discussing a well-designed loft, a loft like the one with in the Matchbox (exact size 66″ x 88″ x 39″), with a flat ceiling and a wide skylight and a queen-size mattress and three-and-a-half feet of space to sit up in. Or like the one in the Pera House, with shallow dormers and loft windows and lengthy dimensions. Most tiny house lofts, however, are designed with little thought toward livability, a casualty of a gabled roof design that looks cute on the outside but feels like a coffin on the inside.

A typical tiny house with a gabled loft—cute, but not necessarily comfortable.

I spent a few nights in the loft of a Tumbleweed tiny house—thankfully, before I began constructing the Matchbox—and reacted so strongly to the claustrophobia of a gabled loft (that is, a pointed roof with a thirteen-degree pitch on either side) that I changed the Matchbox’s roof design to a flat one the very next day. Yes, they look mighty spacious when photographed at the right angle with a wide-angle lens, but sleeping in a steeply gabled loft is a bit like camping in a tent: fun for a few nights, but clearly not built for long-term comfort, and certainly not built for two.

Richie Tenenbaum’s yellow tent, which affords more space than the typical loft (though, presumably, the same level of discomfort).

***

Of course, there’s no right answer here: for some, a gabled loft will do just fine; for others, any loft whatsoever would be absurd. For me, I’m more than happy with the Matchbox’s loft—despite its drawbacks, it’s the best thing for the space and for my needs. And as always, for a chance to check out a variety of tiny house sleeping solutions in person, where you can get the truest sense of scale and suitable sizes, feel free to come by any of the upcoming tiny house tours at Boneyard Studios.

Cross-posted at Adventures in Simplicity.

A workshop designed like a tiny house

We believe tiny house workshops should be like tiny houses: small, intimate, and designed to your individual needs.  That’s why a couple of the professionals involved in building houses at Boneyard Studios put together a tiny house design workshop for the DIYer who wants more technical information and planning materials for their tiny house build. Our first workshop this past fall was a success and a lot of fun to put on, so we are redoing it again this Spring at Howard University.  Find out more details about the workshop and watch a video from our past workshop.  Check out our photos and materials from the past workshop below and see why I, Lee, was motivated to help design a workshop with these professionals after my experience building a tiny house.

Throughout my tiny house project, I have realized how much building requires project planning, understanding major decision points in the process, and a knowledge of building code and materials.  I didn’t fully understand how one decision impacted another or what building decisions and techniques were unique to tiny houses.  I had naively bought into some of the promotional materials in the tiny house world that claim you can build a tiny house with just 14 tools or that make it seem like building a tiny house is simpler and easier just because it’s smaller than a regular house.  Our experience has been the opposite: a tiny house actually requires more planning, and a pretty thorough knowledge of building science, health and safety, and codes (International Building Code, RV code (ANSI/RVIA), and city code and zoning) in order to build a structure that is safe, durable, and is an efficient use of space.  Come learn with us again this spring!

 

Boneyard Studios featured in Dwell magazine

Boneyard Studios was fortunate to be featured in the November issue of Dwell magazine. The current issue highlights small space design and we were photographed and interviewed for an article on microhousing communities.  You can check out the article online or in the print magazine. If you don’t already “like” our Boneyard Studios’ Facebook page, go there to see some photos from the photo shoot (thanks to Eli Meir Kaplan Photography for sharing the photos) .  Also, I don’t blog as regularly as I post new photos and announcements to the Facebook page, so follow us there for regular updates or if you’re an Instagram user, link here.

Screenshot of Online Article in Dwell

Screenshot of Online Article in Dwell

Screenshot of Dwell print magazine cover: Small Spaces, Big Ideas.

Screenshot of Dwell November 2013 Issue: Small Spaces, Big Ideas.

A few clarifications to the Dwell piece/photos:

1) We are a friendly bunch who has fun! (Dwell must have a rule on no smiling as the guys look very serious in all of the photos!)

2) Boneyard Studios is not just dudes (Lee Pera, the female founder of Boneyard Studios, and Elaine Walker, the owner of the little white house, were not on the lot the day of the photo shoot).

3) In addition, many other members of the community were also absent from the photo shoot, including our architects and and another builder.  So many thanks to Foundry Architects, David Bamford of Element Design&Build for the beautiful execution of our projects at Boneyard Studios!

Tiny House Design Workshop – Special discount for 2!

We had a great raffle for the tiny house design workshop being organized by Open Source Tiny House Sept. 14 and 15 in Washington DC.  Given the level of interest we have received from couples or friends who want to take this workshop together, we are offering a special discount for 2 people who register together.  More details are on the workshop website.  We look forward to sharing our knowledge and experience with you over the weekend helping you design and plan your own tiny house project.  See more details here.  And please contact us here with any workshop questions you may have.

Tony

Tiny House Design

Tiny House Design

Learn how to design & build a tiny house with Boneyard Studios!

We are excited to offer a tiny house design and build workshop in Washington DC this September.  We have designed a workshop that includes everything I wish I would have known before starting my project.  I took a tiny house workshop before starting my project, but I still left wanting more technical and design information.  We want you to leave this workshop with all the technical knowledge and the planning tools to start your project!

We will be giving you the tools to effectively and efficiently get started on your own tiny/small house project, including an online project plan with major key decisions and technical resources and a base set of plans from which to design your own house. In addition, the workshop will allow you to tour and learn about different design and construction options from the builders and architects of four tiny houses on the Boneyard Studios lot, the nation’s first tiny house community.

Big Ideas, Small Spaces: A Tiny House Design Workshop

Sept 14-15
Washington, DC

Workshop location is just two blocks from the convention center metro stop and at Boneyard Studios.  We will help workshop participants to get to Boneyard Studios via public transportation or car share.

*Limited to just 30 participants to allow ample time with architect and builder on your technical and design questions

Detailed Workshop Schedule Here

Register Here

We are emphasizing quality over quantity and limiting participation for that reason. You will not be in a workshop with 80 participants but rather 30 participants maximum. This is to allow ample time for each participant to get their technical and design questions answered by the architect and builder.

Questions?  Please enter them below.

insulation options for tiny houses

Let me start by saying I like comfort despite a relatively high tolerance for misery.
In my teens I spent more weekends in a tent, or a hand built “survival shelter” than at home, I have slept wet and cold more nights than I can count, but the coldest, most miserable I have ever been was living in a poorly insulated house in Northern Mississippi.  The warmest I have ever been was in a small stone cabin in the Adirondacks heated with a wood stove (the downside was the trips to the outhouse in -20 degrees)

I also hate high utility bills, for a lot of reasons, but mostly because they are unpredictable both month to month but also over the life of a house.  Investing in a well- insulated, tight house can fix this, but it also raises some challenges.  I want to touch on some of these in this post, as well as some of the myths.

MYTH #1You need expensive windows to have an energy efficient house.  I will probably talk about this more at some point, but I want to put this out there right now, it doesn’t matter how great your windows are, they still suck.  They are holes in your wall that heating exits in the winter, and enters in the summer.  Your money is better spent on insulation.  Don’t think that’s true?  Ask a building weatherization expert, and they will tell you the same thing  – If your windows don’t leak air they are good enough.  Did you buy really expensive windows already?  Great, you still need insulation.

MYTH #2Small houses need less insulation.  Sure, if you are going for a really inefficient house, great, do it, and you might see savings in your electric bill, vs. a typical apartment or house, but I don’t want a tiny house with the efficiency of a 1940’s Dodge power wagon (although if you have a Dodge Power Wagon sitting around that you want to give me, I would gladly take it off your hands).

MYTH #3 – Old builders know best.  Building technology is a moving target, and the last 30 years have seen some of the largest leaps in building technology since the Romans figured out running water and concrete (and that took them hundreds of years). There are a lot of changes that building science has taught us.  Science is the key here: people building things, testing them, and taking them apart years later.

MYTH #4 – “I can’t screw this up that bad, right?”  Wrong.  Some of the risks from a house that is not insulated following building codes and modern construction standards can range from sickness to death…yup, death. (Yup, you will have to read down to catch the details*).

My take on insulation: Put your money where it counts.  I like stuff done right, but let’s face it, sometimes we have a budget that limits what we can do.  We need to understand where and when to cut corners.  This can be really challenging because sometimes even design professionals have disagreed over what is best, acceptable, or just a really bad idea.  But at this point, within the architectural and building fields, this uncertainty has pretty much gone away do to the research that exists.  So, rather than address all housing construction, I am going to limit my comments on insulation to the tiny house world.

Your Roof assembly is not the place to cut costs.  Your insulation is more critical than you think – put your money here! (and not because heat rises).  I am going to assume that all houses will have low slope roofs(that’s what some people call flat roofs) or cathedral ceilings, where ceiling height is at a premium, and building height is constrained.  This means that tiny house roof assemblies will be very difficult (I would argue almost impossible) to ventilate.  We call a roof vented with exterior air a cool roof, and this is how most houses are built to prevent ice dams at eaves.  This can be done for cathedral ceilings, but is difficult, and requires vented soffits and ridge, and insulation must be held a minimum of an inch from the roof sheathing.  – This means less R-value in your roof.  This leaves three viable options for your roof.

ROOF INSULATION OPTIONS

1. Structural Insulated Panels (SIP)  I think for those who have considered this option, they usually think it’s an all or nothing proposition.  This doesn’t have to be the case, and there are some real benefits to going with a SIP roof.

First, inch for inch SIPs will give you as much R-Value as any other roof assembly but with a tighter envelope.  Second, SIPs go up quick, so, in many cases, can allow for a roof to go on in less than a day.  The last advantage I would like to point out is that SIPs offer unique structural potentials that in many cases lend themselves to a tiny house.  SIPs are a type of stress-skin diaphragm that can provide additional structural integrity.  It is important to point out that this additional structural advantage must be detailed properly; however, the inherent nature of the SIPs is a much stronger assembly than a stick built roof, particularly regarding dynamic loads that a tiny house experiences while trailering.  So, SIPs for the roof provide more insulation, a tighter envelope, and faster assembly on site.
2. Rigid Foam Sheathing with spray foam to fill gaps.  This option is a similar  R-value to closed cell spray foam, more likely lower in material cost, but requires more labor.  Translation: if you are not paying for labor, it will cost less, but it’s a lot of work, and you will need to use a combination of spray foam and foam cement to get a tight fit.  While this will not be as airtight as spray foam, it is a good option for the roof assembly.
3. Spray Foam Insulation.  There are two options that might seem confusing, but really are not that complex.

  • Open cell spray foam has a much lower R-value per inch (R3.5 per inch) than Closed-Cell Spray foam and rigid foam.  While it does have some real advantages over batt insulation, particularly with its ability to seal air infiltration and prevent cold spots, for a roof cavity, this will mean a much lower R-value than  Options 1 and 2.
  • Closed cell spray foam brings a higher R-value (as much as R6 per inch after it cures (higher at initial install) and it seals openings in the envelope making a tight skin.  The final deciding factor that I would say makes closed-cell foam the best choice over either open cell foam or rigid foam sheathing is the added rigidity the structure of the framed walls get.

WALL INSULATION OPTIONS

1. Structural Insulated Panels.  As with the roof, inch for inch SIPs will give you as much R-Value as any other assembly but with a tighter envelope.  Second, they go up quick, with less on-site labor and the use of wall SIPs also offer unique structural potentials that in many cases lend themselves to a tiny house.  SIPs are a type of stress-skin diaphragm that can provide additional structural integrity.  It is important to point out that this additional structural advantage must be detailed properly, but if you are at the point that you are building your walls and roof out of SIPs, the manufacturer will be providing those details.  The inherent nature of the SIPs is a much stronger assembly than a stick built wall, particularly regarding dynamic loads that a tiny house experiences while trailering.  So more insulation, a tighter envelope, faster assembly on site. The drawback is that panels are sheathed on both sides, so wiring and plumbing must be run through panel chases.

2. Rigid Insulation with spray foam gaps filled.  This is a good option for R-value, but working around studs, plumbing, wiring could be tough.  One option is to sheath the insulation on the exterior of the house (this would be best done in combination with another type of insulation such as open cell spray-foam or batt).  Rigid insulation on the exterior also provides a thermal break to prevent thermal coupling in the wall assembly, which is a significant benefit.

3. Spray Foam Insulation The real benefit of spray application in walls is its ability to seal at window and door openings as well as to seal around wires and pipes running through walls. My choice here would be closed cell spray foam – higher R-Value, added rigidity to the structure and the ability seal the wall assembly make it the prefered choice.

4. Batt Insulation.  There are 3 basic options for batt insluation.

  • Fiberglass. Fiberglass is the lowest R-Value per inch, but that aside it has some real drawbacks.  A small tight house means condensation entering the wall assembly is a huge issue that can propagate mold in the wall cavities as well as reduce the effectiveness of the insulation. In addition to these issues, I am going to throw in the fact that rodents love this stuff, and anyone who has taken apart a vintage travel trailer has seen the evidence.
  • Rock Wool.  Higher R-value, but still lower than foam options and doesn’t have the issues with moisture that fiberglass does.  However, condensation is still a potential issue that needs to be managed in the wall cavity with a vapor barrier.
  • Alternative (green) batt – these range from wool to blue jeans.  While I don’t have any experience working with these materials, R-Value moisture and pests should be considered.

FLOOR INSULATION OPTIONS

1. Structural Insulated Panels.  For most tiny house projects the built-up framing is a lot of additional structure that is serving very little structural purpose.  Detailed properly this could be a viable floor decking option.   While I have not used this in a tiny house floor, I have used it in other floor assemblies, and think it might work well in some house applications.

2. Rigid Insulation with spray foam gaps filled.  This seems to be the most reasonable option for tiny houses constructed without a vented floor cavity.  If you are sealing the floor, particularly with flashing sitting on the frame, closed cell foam is the best option.

3. Spray Foam Insulation.  The real issue I see with this option is access to the floor cavities, getting a sealed floor cavity makes this a great option though.

4. Radiant Barrier Insulation.  This is a product that is full of controversy, and I take a middle-of-the-road position on it.  Radiant Insulation (the foil bubble wrap looking stuff) claims really high R-value (as much as R-18) and seems too good to be true, except for the price, and then you really want to believe it works.   I spent a week camping in the desert with a radiant insulation material to shield my tent from the sun, and I noticed a huge difference, but that was with the foil exposed to reflect the direct sun, and was not in anyway scientific.  I have talked to several people in the vintage RV restoration world who swear by this type of product.  Keep in mind that my 1974 Airstream has only a 1.5 inch thick wall.

I dont think that you should depend on this for your R-value, but if you choose to use it, keep a few things in mind.  First you need to read how to install it, and if you don’t do exactly what they say, plan on getting a much lower R-Value.  Also, the stuff you get at Lowes and Home depot is glorified bubble wrap.  Those bubbles are where the insulation comes from, so you better believe bursting them will make it much less effective. This also means I would expect diminished effectiveness over time.

The product that I like best of the ones I have seen is called Prodex.  Rather than using bubble wrap, it is about ¼” of closed cell foam with a radiant barrier on top.  The upshot is that you can nail and staple through it. They also specify how to use the product on the outside of a building envelope which means, if you get nothing else from the product, it will do a great job as a thermal break, and can also act as house wrap.

*Finally, MYTH #4 explained.  Tight houses mean less air is leaking out of your house.  This “leaking” is bad for thermal efficiency, but living in a sealed jar isn’t all good either, and could be dangerous.  Many conventional building materials off-gas all sorts of chemicals.  This can cause a range of short-term and long-term health problems.  A recent example of this is with the post-Katrina FEMA trailers.  In addition to new materials chemical off gassing, your indoor air quality is impacted by things like mold, dirt, and even rodents (and their excrement).

We have seen a range of these issues in the press in the last few years.  I really don’t think we need to fear these, but we need to build smarter, especially with Tiny Houses.  We also need to consider those who might own our houses later in its life cycle.  Maybe you plan on using it occasionally, but then you sell it to someone who lives in it full time. The chemicals you put in your house might not be an impact to someone in the house for short term stays, but the daily impact could be much more significant.

The other issue you need to be careful of with tight envelopes is making sure you are properly venting your combustion appliances as well as your waste lines and tanks.  Putting a carbon monoxide detector in your house if you have combustion devices is a must.  See this article for more details.

Glossary:

R-value – http://en.wikipedia.org/wiki/R-value_(insulation)
Insulation – http://en.wikipedia.org/wiki/Building_insulation

Thermal Bridge – http://en.wikipedia.org/wiki/Thermal_bridge This is an important concept, and often an overlooked issue.

on choosing plans: designing by doing

Like most people building tiny houses, I had limited options when purchasing plans for a tiny house over a year ago (up until recently there were only a couple options), and none of them fully met all my needs.*  So, I did what I saw others doing and bought the Tumbleweed Fencl plans, knowing that I would significantly alter the interior.  But unlike most people building tiny houses, I was fortunate to be able to spend a lot of time in the Fencl this summer while it was sited on the Boneyard Studios lot.  While there are many things I like about Tumbleweed’s design of tiny houses and I have benefited from their expertise, I quickly realized there were also many aspects of the Fencl that didn’t work for me very well.

Fencl getting moved from the Boneyard Studios Lot

I think it’s necessary to follow plans for a project like a tiny house on wheels, but there is also a benefit to leaving some room to change pieces of the design as you go along.  The typical tiny house look – traditional wood siding, pine interior – just looks too cabin-like for our urban location. Nothing against the cabin-in-the-woods aesthetic, but in an urban environment I wanted to try something a bit different.

So, what a relief and joy that now – six months into this project – I finally have architectural plans being drawn up for my house.  It makes brainstorming about design issues and implementing those ideas much easier – very helpful since the design has changed considerably from when the little house first rolled up from South Carolina.  Here are just a few of the changes we’ve made:

Exterior look: A four-foot locust porch attaches to the trailer and can be removed and stored inside when ready to move.   The extra foot of porch space (a lot of tiny house designs just have 2-3 feet) makes a big difference…you can actually sit on the porch without your feet hanging off of it.  Two boxes at the front of the trailer (back of the house) will store my water tanks and serve as extra storage, but they will be wrapped with cedar siding in a way that doesn’t make them look like boxes hanging off of a house but rather integrated into the design of the house (pictures to come when completed).

Locust rain screen siding and deck

Locust rain screen siding and deck

Deck in construction

We are implementing a rain-screen approach on both the house and roof. To get an idea of what that looks like, here is a rain screen design on a much larger house.  We are using locust and cedar from a local lumber mill in Virginia that sells sustainable rough-sawn lumber (from already-downed local trees and construction sites). Stay tuned for a future post on the benefits of rain screen siding approach and more on working with rough-sawn lumber as siding.

Rain screen siding going up on tiny house

Protohaus Sink/Kitchen

Kitchen: As someone who enjoys cooking and conversing with others while cooking, I didn’t like the fact that the Fencl’s kitchen is so closed off – if you’re cooking you can’t see or interact with anyone who may be in the main room.  Pictures of Fencl kitchen here.  Jay even mentions in his Tumbleweed workshops that he doesn’t do much cooking, so it doesn’t surprise me that he would opt for a small kitchen space.  However, I wanted my kitchen to feel more open and be multi-functional – something similar to the Protohaus kitchen pictured here.  By having a stool or two that can saddle up to the countertop, a friend can sit and chat with me while I cook or with someone seated in the main room.

View of Protohaus open-style kitchen in back

Loft:  The loft in the Fencl felt too claustrophobic to me. I knew this just from seeing pictures, but being able to hang out in it confirmed it for me. So, Tony built dormers and a new roofline on my house. The difference is huge – it feels so much more spacious and the light coming in from the dormers creates a lot more natural light in the whole house. We also plan on creating a little platform off the loft and a ladder that will be counterweighted to raise up when not in use.

Hanging out in Fencl loft

Loft from inside with dormers and shallower pitched roof

New roof, EPDM rubber roofing on (preparing for rain screen siding over it), and new dormers

Size of features: The proportional aspect of features should be taken into account in tiny houses, but it doesn’t need to inform every decision.  I got a great deal on some large windows on Craigslist, but when I taped out the dimensions on the tiny house I realized they would look goofy on such a small structure, so I opted to spend more for smaller, custom windows that fit the dimensions of the tiny house better.

However, not every feature in a tiny house needs to be small.  While originally I thought I would opt for everything smaller inside the tiny house, I quickly realized a lot of the tiny features just annoyed me.  For instance, I couldn’t easily walk through the small door of the Fencl with a couple bags of groceries. The entrance between the kitchen and main area was also too narrow for my tastes.  I tested out washing a soup pan in the small sink and was frustrated by its size. Thus, I’m doing some things differently like putting on a regular-sized exterior door.  Furthermore, by creating a countertop/cutting board (made from paperstone) that can sit over my sink in the kitchen, I can use a larger sink without sacrificing valuable counter space.

Again, being able to try out the space in an already-built tiny house was very informative and made me rethink some of my initial ideas on how I would build my interior, opting now for creating features that are multi-functional, but not necessarily always tiny.

For those of you who have used Tumbleweed’s plans as a basis for your projects, what are some of the design modifications you have made?

*I really wanted to purchase plans for the The Protohaus, but after waiting many months hoping they would be done, they still were not available when I needed to purchase mine. Had I known about Dan Louche’s plans when I began, I would have purchased them since his are the only available plans I’ve found that include dormers and an open kitchen design spanning both sides of the trailer). Once completed, my tiny house plans will be available as well.  As someone who has shopped around for plans and drawn inspiration from many resources, I think having more options rather than fewer is a good thing.

lot design, take II

A revised site plan for the showcase, with 4 tiny studios on wheels, shipping container storage, south-facing garden area, limited parking, and fruit trees.