An Old Coal Miner Looks at Affordable Housing:

Details

Last month I presented the outline of a design for a catenary strawbale house.  I felt that was enough information to spark any interest there might be.  All details should be worked out by competent and committed structural engineers.

I have decided that some details shouldn’t be left to the tender ministrations of an engineer.  Some ideas are too good to leave alone.

Roofing, wind, interior treatment, snowload, and compliance with the strawbale building code are  issues demanding more investigation.

Roofing:The bales must have a set of nailers wired to the inside frame for securing the metal.  These may be any sort of wood, including slabs.  By wiring them across the bales, the pinning of the bales (required by code) is accomplished.    The roofing and felt is then screwed down to the nailers in the normal fashion.

Wind:The nailers should also be secured to the concrete slab by cables and turnbuckles anchored in the concrete.  This will help to maintain the curve and insure the  stability of the structure.

Interior treatment: The simplest interior would be chicken wire and paper above the frame.  The paper could hold a layer of plaster (or, hopefully, not!).  Simply spraying with texture and paint would give a Bauhaus (or 80‘s New York) feel to the interior. The treatment must allow the interior to breathe.  Air and moisture should be able to pass out of the interior.  No house with soggy straw will be very pleasant.

Snowload: While most of the snow will end up on the sides of the structure,  Provision should be made for protecting the curve.  If the curve changes shape, side thrust can destroy the structure.  A steel sheet on the side wired to the sheet on the opposite side will stop side thrust by keeping the wire in tension.  Steel wire is very strong in tension (a fact most frequently trumpeted by Buckminister Fuller).  The roof can be attached to the sheet with self tapping screws, of course.

Compliance: The provisions of the strawbale building code are largely for houses with conventional roofs.   The pinning of the bales has been discussed.  The roof must be pinned tot he back wall by driving rebar into the bales.  Plastering is another issue which needs consideration.  The back wall must be done as with any conventional strawbale home, but the arch should be modifiable.  Ventilation of the straw could be done with screen ventilators as in conventional attics.

A small strawbale home, off- grid, with composting toilet, and rainwater plumbing poses many compliance “problems” for government.  Solving those “problems” will go a long way toward creating a saner world.