We are building inside Port Townsend city limits, in Jefferson County, Washington. The house has straw bale exterior walls, which will be coated with stucco. The weight of the roof is supported on these walls; making this a Nebraska style, or load bearing, straw bale structure.
The house was designed by a local architect, Chris Stafford, who is familiar with straw bale construction, and who endorses building with products which are environmentally less destructive (or even benign :-), and which are less toxic to live with. He has helped us choose materials with this in mind. His credentials as an architect and his experience with straw bale construction have made it easy for us to get building approval from the city; we received our permit within the normal time Port Townsend takes to process any application for new home construction.
The house is fairly large and ambitious for load bearing straw bale construction. We have a poured concrete basement over two thirds of our building footprint, with the rest being crawlspace. The floors are supported by engineered lumber (BCIs, Parrallams, and another style of beam), which are pricy, supposedly use scrap or tree farm wood vs. old growth, and vary and flex less than true lumber.
The house is L shaped house, and is essentially two connected structures, with an interior straw bale wall in order to avoid a span too wide for the load bearing straw. The second "half" story is only over the larger section of the house, and is independently supported on posts. The main section has eight bale high walls. The smaller kitchen section is one story, with six bales high walls. It has a stick frame cantilevered dining nook with windows all round. The straw bale walls of the kitchen section are strapped to one side of the main house rectangle, tying the two sections together.
The bale walls rest on a horizontal ladder-like structure built from 2"x4"s, and lined with black asphalt felt paper. The ladder "openings" are filled with gravel; this creates a space for any moisture entering the straw walls to sink to. There is actually some drainage built in, as the outer 2"x4" has tiny slots created by a saw blade for this purpose. The expectation is that there will never be any moisture in this ladder! The ladder also keeps the straw walls a inch above the interior floor level, and above bathtub overflows, etc.
A connected box beam style top plate sits on the straw walls. It is wired down through the floor, under the foundation mud sill and under floor joists. The roof trusses are nailed to the top plate conventionally and with hurricane ties. This house won't be going anywhere!
Our lot is sloped, which is not really ideal for a straw bale house. We take advantage of this with a daylight basement under about 2/3 of the house. The basement will not be insulated or heated.
The building footprint is approximately 1540 square feet. However the two foot thick walls mean that the interior space on the first floor (the only full size floor), is only about 1020 square feet, and the upstairs is 716 square feet. The upstairs walls are only 24" high pony walls. The roof pitch is 12:12, and formed by scissor trusses. Two shed dormers give us more full height space on the second floor. With these areas we have about 460 square feet on the second floor where the ceiling height will be over 7 feet. So the total finished living area is close to 1500 square feet, but we will have extra storage space upstairs, and the unheated basement as craft, shop, and storage space.
We did not hire a contractor. Instead, we are hiring subcontractors directly, and are participating in several phases of the construction. Chris Stafford has overseen the straw bale wall construction, which took place August 1st and 2nd, 1998. The bales were stacked to form the walls during this two day work party, and the top plates were raised and secured to the walls. Additional strapping, straightening, stuffing, and trimming continued for several weeks after.
We hired framers to build the interior walls, the second floor, the stairs, and the roof structure. We hired a stucco crew for the outside, and had lots of hired help with the shingles on dormers and gables. Professionals roofers completed the roof with composite shingles also; we don't really enjoy the view from our 12:12 pitch roof. Insulation of the floors and ceilings, and installation of drywall on ceilings and interior walls was also hired out. In spite of all this, we seem to have plenty of work to do, including plumbing and wiring.
Revised 5/1/99 (this page not Y2K compliant)