Monday, September 14, 2009

Building a Straw Bale Greenhouse: Phase 1 by Gardener Cumax

The foundation corners were laid out last Sunday. The stakes were set at 18' x 12' but they weren't square. I had a friend come over and help me square the foundation lines. This is the single most important step. Over a 18' x 12' area we were able to get the diagonal measureme
 nts within 1/4 inch. Pretty impressive adjustment because one could go all day in tweaking the stakes 1/8 of an inch and never quite get it right.
 My friend got it on the second  adjustment. It really takes two people to square the foundation corners be

 cause it involves constant measurement. We adjusted two stakes on the same line (The two red corners on the right were moved down). We moved the first stake, and then when we moved the second, I would measure it so we were moving its outer corners to exactly 12' and 18'. Then we measured the diagonals. We repeated this adjustment just one more time. The red line shows the slightly trapezoid shape from the initial stake layout. It was two minor adjustments of 6" that made it square. When you're looking at this from the ground and you have it perfectly measured out you can't see the slight non-square shape. It's impossible. And it would take too long to square it on your own. It can be done, but two people make it much more accur
 ate and faster. The green line shows a squared foundation line. A perfectly square foundation means one will have square walls and a square roof.

But wait, I'm using strawbales for the walls. Will they be squared too? No. That's where the RBA (roof bearing assembly) comes into play. Once the concrete is poured and cured, one builds the RBA to perfectly math the foundation. The RBA caps the strawbales and then the RBA is squared to the foundation by shoving and using a level and measuring the diagonals. Once we got the stakes as perfect as we could we drove them deep into the ground and started digging. My spading fork broke - finally - in the hard clay. I've been gentle when it comes to this part of digging but after maybe 10,000 digs and wiggling the clay the neck finally gave out. I have another friend who has a mini-excavator who might be able to haul it out of the mountains down to our place to dig out the rest. I don't want to break any more spading forks