Editor’s note: Kent Earle and his wife, Darcie, write a blog called Blue Heron EcoHaus, documenting their journey “from urbanites to ruralites” and the construction of a superinsulated house on the Canadian prairies. Their previous blog on GBA was called Placing the Concrete Floors. The blog below was originally published in August 2015. (A complete list of Kent Earle’s GBA blogs is provided in the “Related articles” sidebar below.)
We knew we wanted a black house. In fact, when designing the house, it was one of the only things that really remained consistent and we didn’t change our minds about. (OK, truthfully, we strayed a little bit — testing the waters. But as they say, once you go black, you probably won’t go back… or something like that.)
Our previous house had been painted black by the previous owners (we are soul mates) and we loved it dearly. But really, we did not want to simply paint our new house black. Paint is great for covering up years of other layers of toxic paint, as at our old house, but not as an initial coat. So, what to do?
In the process of researching, planning, and designing the house, we collected hundreds of inspiration pictures. The majority of my “architecture” folder on Pinterest is of black houses. I’d look at each one and try to figure out what they used: paint, stain, or something else?
One of the first “something else” options we were initially really drawn to was the traditional Japanese siding treatment called shou sugi ban. An article posted at Treehugger said: “This is a traditional Japanese method of preserving cedar, where it is burned enough to create a layer of char on the outside. The char serves a number of functions: it seals and preserves the wood, it makes it significantly more fire-resistant, and termites and bugs hate it.”
It is said that this type of treatment can allow the wood to survive for 80 to 100 years without maintenance and much longer if treated with oil every 15 years.
A video of the traditional process in Japan.
OK, so just imagine doing that 200 times over to clad your moderately sized house. Now that is labor intensive! Most people nowadays, from what I’ve read, use a blowtorch to char each board, then dunk it in water, scrub the charred bits off, and then oil it. Even with a blowtorch, this a crazy amount of work, but in the end you get something really impressive and unique.
Let’s find a more reasonable alternative
I really thought we were going to do this for our place. However, there were a few reasons we abandoned this idea. Firstly was the obvious: OMG, that would be so much work! Second, cedar is crazy expensive right now, running in the range of $7 to $9 per square foot. But the final reason was that we had heard that someone had decided to do a house in shou sugi ban in the City.
Curious to see it in real life, we drove over to take a look. And well, to be honest, we really hated it. Perhaps it was just that the people who did it did a bad job, but it looked really… gross. It basically looked like a house that had had a fire recently go through it (which I suppose is true). I think I would like to test it out on a shed or coffee table or something before I invest thousands of dollars in the siding of my house and ended up hating myself over it.
So, we turned to the natural (and perhaps most obvious) option: stain. Stain is all well and good, but you really need to stain your wood every five years (or less) to preserve the wood and keep it looking good. And really, you still should use cedar to have optimal rot protection with plain old stain. That’s what we thought, at least, until my wife came across a little black Swedish house called House Morran.
Granted, this house is actually sided in plywood, which I would never do, but what intrigued me was the rich black color, and the fact that the grain of the wood still came through (unlike with painted siding), and that they had used a siding that was not cedar.
As I read more about this house, I discovered that they used “black tar” for the siding. Through some detective work, we eventually found this same house linked to a Swedish product called Auson black pine tar.
I had never heard of or seen this product before, but I was very intrigued. Also, it was Swedish, and seeing as our house had a lot of Scandinavian inspiration, this only seemed fitting.
We found that the product was available in Canada through a website called Solvent-Free Paint. Score. We emailed the company to learn a bit more about it:
An all-natural product
We corresponded with John Sinclair at Solvent-Free Paint, the Canadian distributor, who wrote, “Genuine Pine Tar is one of the more effective wood preservers we’ve seen, and it is all-natural, which is amazing. In Scandinavia, they have been using pine tar for around 1,500 years as a preservative on everything from stave wood churches to wooden splint roofs to Viking ships, and it is still the predominant choice for continuing to preserve these old wooden structures to this day. Amazing. In fact, the heritage arm of the government of Québec has been making studies on this with respect to preserving wooden roofs, and its current recommendation is to use pine tar.
“Pine tar is made from burning the pine resin out of the stumps of pine trees. The sticky resin is then collected and cleaned to various degrees, and pigment is added for color. In this state, pine tar has the consistency of molasses and can be used for preserving wood, even below grade. Above grade, we recommend mixing pine tar 50/50 with Allback Purified Raw Linseed Oil and applying it warm so that the pine tar and oil mixture really penetrates the wood. This mixture offers the best of both preservation and nourishment for the wood; it also takes down the stickiness of the surface so that it is more pleasant to touch or walk on.”
Even better, this product is ideal for use in Scandinavia, where pine and spruce are much more readily available and cedar is not. It preserves the wood and needs to be recoated only once every 15 years.
Bingo, we’d found our product. We ordered a few liters of this stuff. We had debated about using cedar for our soffits as well, but once we saw this, we realized we could use pine lumber treated with a natural clear pine tar for much less than half the cost of cedar.
Soffits come first
We started with the soffits, which would be easiest to install first. Yes, it is true that most people use aluminum or vinyl vented soffits, which are foolproof but also so incredibly boring. Instead, we purchased 1×6 tongue-and-groove white pine.
Now, one thing you need to know about staining (or painting) wood for siding or soffits, is that you mustn’t let any part of the wood be left untreated (otherwise the lifespan of the wood will drop by 50% to 75%, so preparation is key)! That is, you must stain all six sides of the wood. For the tongue-and-groove pine, this meant that, yes, we had to stain the tongue and the groove, which is a crazy, tedious, and annoying task.
We had about 800 square feet of soffit to stain on all sides — twice. It took us about 14 hours, but it looked pretty nice by the time we were done. The pine tar was actually easier to use than we expected. Once mixed 50/50 with the linseed oil, it was really just like a slightly thickened stain. It brushed on easy and evenly.
However, we had to keep it warm. On the hot 30°C (86°F) days, it was easy, but on the cooler days we had to heat it up on the stove in the shop. Also, each coat took between four and seven days to dry, and even then it still had a bit of residue on it that, hopefully, will dry someday. Surprisingly, it was not at all sticky. (I had fears of moths and dust sticking to the house.)
As for venting the soffits, there is a calculation of square footage of ventilation versus square footage of attic space which is approximately 1 square foot of venting to every 100 square feet of attic. We figured a gap of about 3/4 inches by 30 inches lengthwise along every fourth board would be about right. We used a router to cut the gaps and covered it with a bug screen.
I was so impressed with how well these boards turned out. Much better than I’d expected, to be honest.
Next up was the siding, which I was most excited about. We ordered the tight-knot white pine siding as a “shiplap reveal” in 1×8. That pile took a ridiculous amount of time for us to work through. I had expected it to go relatively quickly, seeing as we did not have to stain a stupid groove, but 30 hours later we were finally done.
We were exhausted, but man, did it look badass. (See the photo below.)