Gearing up for construction season this coming Spring, I've been focusing my attention on acquiring the straw bales that will form the walls of our house and workshop. After poring over our green building books and various online sources, I compiled a checklist of guidelines for finding good material, and started scouring Craigslist for the perfect bale. Here are some of the criteria I'm working with:
There should be no weeds or seed heads in the bale.
The moisture content should be lower than 15% (when checked with a moisture meter).
The straw should smell sweet and fresh (any hint of mustiness is an immediate no).
The bale should be bound very tightly. You shouldn't be able to stick your whole hand in a bale—just your fingers.
Lift and then drop a bale—it should rebound slightly.
Kick a bale. Your foot should rebound slightly, not sink in.
Set the bale upright and press on the top, trying to bend it. It should be difficult to loosen strings this way.
What material is the straw baled with? Wire? Sisal? Twine? Baling twine is best. Sisal shouldn't be used.
Most of the farmers I spoke with had at least a passing knowledge of straw bale building, but a few had no idea what I was talking about. The biggest show-stopper among all of our potential sources was a simple lack of quantity. We need about 400 bales to complete the walls for the workshop and house, and we'd like to get them from a single farm.
Our first viable option was located in western Massachusetts. Armed with a moisture meter borrowed from our friend Rob, we set off on a grey, foggy day and drove two hours to see the bales. After meeting Henry the farmer and visiting his hay loft, we went through our entire checklist.
In the end, we decided to pass. The bales were bound with sisal (which we've read decomposes quickly), and they weren't very tight. In actual fact, they may have been fine, but never having done this, we've decided to follow the recommendations in our books pretty closely. All in all, the visit was a good learning experience—it was really satisfying to take the first steps towards acquiring the material for the walls of our house!