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Every step of building a house has taken longer than expected. I thought my partner and I would build our cordwood walls in three to six months.
If you're new here, and haven’t read my previous columns about my house; cordwood is a way to build walls by stacking logs as you would a cord of wood, adding mortar between the logs on the outer few inches, and insulation around the mortar.
We are mixing hydrated lime and sand to make the mortar - simple but requiring a precise preparation with precise weights.
It isn't a huge home, just about 1600 square feet, and only one story.
My estimate for how long the walls would take was based on naiveté and reading a blog by a couple who built a cordwood home. In addition to the blog, I read a few forum posts by cheerful contributors who had built cordwood projects and reported relative ease and speed.
Now, almost 11 months of cordwood later (two summer seasons) I realized that those forums posters may have disseminated unreliable advice.
Unfortunately, it's not the only time internet homebuilding advice has misled me. Just a few days ago, my partner and I realized we made a mistake when installing the subfloor, under where our rocket mass heater will be.
We are preparing to start building our stove, which will heat the entire house. Several years ago I read a lot about this style of stove, air flow, heating principles, construction methods and related topics.
Not wanting to pour a big concrete pad, I turned to the forums for advice about placing a mass heater on top of a wood subfloor. These types of stoves are relatively rare in this country, and forums often offered more information than other resources, as those who build and use these stoves share knowledge.
Most posters recommended installing a rocket mass heater on concrete, or even on a dirt floor. However, I found several people asking if it was possible to put one on a wood floor. The answers were - yes! It would need reinforcing, but with enough support, a wood floor could structurally support a mass heater.
Great, we thought. We will add a bunch of extra support. We did some math, and then overbuilt the subfloor.
I knew we'd have to fireproof the subfloor, and didn't see any recommendations for that process or materials. But I thought about creating some air channels and insulation between the firebox and combustibles. The details were a problem for later.
Well, now it is later, and the details are indeed a problem. I thought we'd cover the wood floor with cement board, tile it, add some bricks, and then start our build.
To be certain though, we took a quick look at the International Building Code regarding mass heaters. Lo and behold, my plan was not admissible. Brick conducts heat too well, and cement board and tile can as well.
Since heat travels up, and there would be several layers of brick on top of the floor, I suspect that our plan would present an incredibly low risk of setting the subfloor on fire.
However, since the IBC said at least 12 inches of concrete are required as a footing/foundation, we've had to rip some of our subfloor out, in order to pour additional concrete under the heater’s core.
Although this has served as a great reminder to not rely on internet forums for reliable and sufficient information for important details, I'm not totally confident that I won't repeat this mistake in future. I'll keep you posted.