Tuesday, March 20, 2012

Spring Broke

"Spring Break" has been spent busying ourselves in the back end of the house - the focus of our efforts over the next couple of months.

The CMU retaining wall is pushing in substantially. The cores of these blocks don't appear to be infilled or reinforced - one of several reasons for their failure. Even more problematic - the walls above them rest on a small concrete strip which is resting atop the dirt adjacent to the wall, far above the frost line. The movement of this footing has been substantial enough to crack it in half and release a sizable amount of soil and water pressure onto the wall - as well as the gravity loads coming down from the house.

The last of the dirt that has washed its way in and pieces of rotting wood that hang off the west wall are cleared from the space. Despite these being structural members soundly nailed at numerous points (at one point), they come down by hand without a fight. With a push of a finger, the saturated wall moves inches, as if made of fabric.

To keep the concrete footing and the soil beneath it from caving in as we remove the blocks - the weight of the wall has to be removed from it. We fashion together several large beams by lapping scrap 2x6's and other materials together and span above and beyond the extents of the wall to be removed. Oversized and turned studs are put in between a lower and upper beam and nailed wherever possible into the existing wall in hopes of relieving the foundation of its weight.

The reinforcement in place, a strategy for rebuilding the wall needs to be prepared and fine-tuned. We weigh our options: concrete blocks, a new site cast pour (expensive), and finally - an earth tire foundation. Tires have a daunting presence in these types of neighborhoods. That inability to decompose or deteriorate which makes them such a nuisance to get rid of makes them invaluable for our purposed. We've long considered a tire roof, but the tire foundation is a more pressing matter and involves much less processing of the tire (cutting them is very difficult). What's more - these already have a fairly well established building method only using dirt as a filler material. And their large footprint make a poured concrete footer unnecessary.

We grab 50 tires from the first place we find them, roughly 150 feet down the street, and leave about 30 there. A local auto shop farther down the street urges us to take as many as we'd like and many more. Material sourcing is not an issue.

The tires are sorted by (course) height and diameter in preparation for the build - hopefully to begin soon.

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