When people find out we’re building a house of straw, their first reactions include incredulity and a few jokes about the big bad wolf. Once they realize we are serious, that disbelief turns to interest, and soon they’re asking questions. "What do you cover the straw with?" "How do you keep the straw dry?" If they know a little about construction and then a just bit about straw, they say, "That's going to be a huge foundation!" Yes, indeed, it will be, and we tackled that foundation this summer.
Since the bales we plan to use will be eighteen inches wide, that means we’ll need a foundation that is also eighteen inches wide. The frost line in Torrey is 30 inches below the earth’s surface. That means we need a foundation measuring 18” wide and 36” - 40” high all around the approximately 150-foot perimeter of the house that will be constructed with bales of straw. That’s A LOT of concrete. To reduce that amount, we opted to build a rubble trench foundation.
To begin preparing the house site, Scott mowed the meadow grass. (We aren’t big fans of mowing or lawn. This might be one of the only times I’ll ever see Scott use a lawn mower.) Then Tyler Torgersen brought in his crew to remove the top soil. Next the crew dug a narrow trench at the house’s perimeter. They positioned perforated pipe throughout the trench. The pipe’s purpose is to drain any moisture away from the foundation. Typically the pipe runs to daylight. Our property doesn’t have much slope, so, rather than going to daylight, our perforated pipe goes to a dry well that is eight feet by eight feet down to about five feet below the surface where the ground water runs. They filled the trench and dry well with gravel. Finally the crew poured about two feet of foundation concrete.