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We’ve been busy spending time with our son, Dave, who’s off to college, so have collected a series of posts about the updates to our straw bale ag building.

We’re now concentrating seriously on the exterior surface of the building.  We need to get the thing weathertight before the rain!  The burn is on ... only really, the burn has been on all spring and summer.  It just takes a very long time to construct a straw bale building on a farm!

The series of pictures in this posting show the stage we were at two weeks ago, where we were very focused on the lathe and staples.  The basic concept is this:  now that you’ve framed your building and stacked bales of straw all around its perimeter to form walls, you need to provide lateral strength and cohesion.  You need something to tie all those bales to each other (aside from the friction imposed by each on its neighbors) and to the frame.  Even though we carefully tied the courses to the framing elements, the bales are held in place only by twine which honestly does not seem like a sufficient method of ensuring their permanent conscription in the place they were originally put.

Thus, the need for lathe, staples, and eventually stucco.  Lathe is a fancy term for chicken wire.  I’m told by Drew that the lathe actually is not chicken wire.  It must be specially coated, galvanized, something that makes it other than chicken wire in its non-visible characteristics.  To the naked eye, it is, for all the world, chicken wire.

The lathe must encase the straw bale structure, covering all the straw surfaces and continuing on to cover all the wooden surfaces above the bales.  Everything except the roof has got to be covered in lathe.

The function of the sheets of lathe is to (1) keep the bales in place along the vertical faces; (2) maybe provide some shear strength, although I’d guess that function is a minor one; and (3) act as a rough surface to which stucco can eventually adhere and bond.

After cutting sheets of lathe of workable lengths—usually about 12’ long, and the strips are 3 or 4 feet wide—we placed them onto the exterior wall and maneuvered them into place in a roughly horizontal configuration, and with some overlap with the prior (lower) strip of lathe, if there was one.  Then we scrutinized the bale surfaces to make sure there were no low points, divets, cracks, etc.  If any were found, we’d need to reach up or down under the lathe sheet to fill the area with loose straw.  Finally, it would be time to attach the lathe sheet for real.

Attaching lathe involves (1) stapling it like crazy to any wooden edge you are lucky enough to have (not always the case, but true of window edges, bases of walls, and tops of framing walls), and (2) “stapling” it directly to the bales themselves.

The first kind of stapling involves traditional staples from a staple gun.  The second kind of stapling involves homemade staples, about 7” deep, made out of high-tensile wire (about 3/16” bore, I’d estimate), that get pushed through the lathe, into the straw bales, and hammered home if necessary.

We invented a great staple shape that is shown in the pictures.

Next up:  testing the lathe work we’d done to make sure it would hold stucco.

Dan

[slideshow id=76] Yesterday Drew and I spent the day sheathing.  Good thing he is the guy with the plan.  I don’t need to know much about sheathing, but I’m very good at measuring a spot that needs a piece of wood, pondering about rotations, translations, and other geometric transformations, marking plywood, re-measuring, mentally cutting out the shape from plywood and matching it up to the hole, cutting the actual piece, and ending up with a really good hit rate for the thing actually… Read the rest of this article »