When we begin building our straw bale walls next week, they will go on a strong and beautiful foundation – the second round of slip-form stone wall in Underhill House. This wall has something that the first one didn’t.
As Doug and I have worked on the slip-form stone walls for our house, we have fallen in love with this way of making walls. See my posts on slip-form stone walls (Part 1 and Part 2 We’re using local stone and a minimum of concrete to hold them in place, all formed within the framework of a temporary wooden form. It is hard work, and takes a lot of thought and attention but can turn anyone into a stone mason and creates a sturdy, solid wall reminiscent of the stone foundations of the old dairy barns in this part of the world.
The process of selecting the right stone to fit into each spot was challenging and satisfying, and the physical work of mixing and shoveling the concrete into the spaces between rocks was a good work out.
Then there is the dramatic moment of removing the wooden frame and seeing the finished wall. Lastly, knocking out concrete that has oozed into the front and filling all the gaps with mortar is another chance to be expressive and physical at the same time.
The stone wall is 10 inches wide, and the bales are 18 inches wide, so the extra 8 inches of bale support has been made with a wooden frame that will be filled with insulation, along with a 2 inch thick Styrofoam panel between the slip form wall and the wooden frame. In this upper wall we decided to set the wooden support for the straw bales back a full inch in order to add some metal flashing over the interface, and the process left a two-inch gap that still needed filling between the Styrofoam panel and the slip form wall.
In general, we have been using just about every scrap of material generated on the job site as we go along, and that means there is something major missing from our building site that is almost always present at any building or remodeling project – no dumpster.
You know the beast. It is the first thing to show up, the better to haul away unwanted material to a landfill.
According to the National Association of Home Builders (NAHB) study, an estimated 8,000 lbs of waste is created from the construction of a 2,000 square foot home. Almost all of that waste ends up in landfills.
Our construction manager, Bryan Dalstrom is working to use and reuse everything possible on the site. He is very careful with his dimensional lumber, using it for bracing and later for framing. With the slip form walls, we mixed up our concrete in small amounts to make sure we would not have a huge glop hardening into something that looks like fossilized dinosaur poop dumped in some remote corner of the building site.
Mike Flynn, who poured our foundation and below-ground walls, calculated very carefully and produced minimum waste from his work too. (Very small dinosaur poops from that project, and quite a bit of it was broken up and used as filler in our slip-form rock walls.) In fact, Tom Spicer, our slip form guru, has asked if he could take the remnant concrete nuggets that did get generated for use as filler in his future slip form projects.
Another waste stream we’ve avoided on site is the port-a-potty, with it’s noxious chemically sanitized soup. We’ve gotten by with a simple luggable loo that is surprising not odorous when dumped off in the woods. In fact I’d say the crew seems proud of the fact that there’s no chemical toilet on site.
The sawdust from the milling process has been collected and stored for later use as a soil supplement.
Rather than generating waste products in this building process, we are trying to use some up. The soffits of our roof are made of discarded wall-to-wall carpet. The underside has a pleasing, neutral look, and it is virtually indestructible. (Those carpet fibers will outlast us all!) The entire sod roof will have a layer of recycled carpeting as a base to provide friction before the soil is added.
Back to the slip-form stone walls — I’m going to love this upper section even more than the first because I know it is filled with scraps that are keeping us warm or cool, as the season dictates, and also keeping the landfill a little less bulging.