Thursday, December 10, 2009

Building a Straw Bale Greenhouse: Phase 2 by Gardener Cumax

The straw bales were laid on top of the foundation. Then the RBA (roof bearing assembly) was laid out on top of the bales. The RBAs consist of 2 sheets of 20" wide by 22/32" thick quality plywood. They were screwed together, and then a thin 1" x 4" screwed to that to act as a rail or guide so the RBA didn't slip and slide off. Each corner was pre-assembled so as to be perfectly square. The tall X at the far end is my doorframe. It's 4' wide and perfectly centered.

In this photo, I'm hammering in edge pins. Though the bales were uniform, custom bales sometimes lose enough straw to require adding extra straw. Though it doesn't appear so in this photo, the bales were tightly compacted. It was easy to grab a chunk and simply "nail" it to the bales.

The next photo gives me the heebee jeebies. That shiny diamond pattern metal is lath. It is razor sharp and as aggressive as a cholla. I have a 3+ inch gash on my left knee! The lath is what holds the stucco. I bought extra stucco to over-simulate the weight of the roof. It's going to be a light roof, sturdy to be sure, and it has to be due to the winds we get year round. The big pieces of lumber under the stucco bags are the concrete foundation forms. They serve to spread the weight around.

Below, you can see the exterior walls with a base coat of stucco. The front wall and the left took 2 hours (!). Stucco takes far more time than I thought it would. This part of the project has been extremely frustrating for me. Doing it alone is exhausting.

First you have to get those 80# or 96# bags on edge, cut them open and then dump into the cement mixer. Don’t breathe cement dust - it's toxic, even with precautions. Then grab exactly 1.6 gallons of water and add it to the mixer. Turn it on and wait 5 minutes. Dump half of the stucco out and haul it over to where it needed to be applied. Get it on the trowel, bend over and smash it into the lath from the ground up. Repeat with the other half of the stucco. Stucco will crack if it freezes while drying. I do have some cracks but they are easily repaired.

For now it is covered in black plastic, neatly, uniformly wrapped as if it were a Christmas gift to the winter solstice sun. I will leave it wrapped until there is a spell of warm weather.

While waiting for that, there's nothing to stop me from getting the walls and roof in place and to cap with polycarbonate. The cold I can deal with, but the snow presents extra logistical obstacles to work through. We'll see how this plays out. So close to being done!