Natural building communities have striven for decades to establish straw as a viable building material, but have until recently focused primarily on fostering labor intensive hand-stacked straw bale construction methods. Progressive architects, engineers, and builders have incrementally refined the method of straw bale construction such that the best built straw bale homes rival the performance, durability, and comfort of high-end, high-tech construction—all while dramatically undercutting their embodied carbon. But this method is optimized for the communities from which it arose: scrappy owner/builders, rural homesteaders, off-grid aspirants, communities isolated from speculative development and state funds, DIY enthusiasts, and radical idealists.
If straw building advocates hope to significantly influence carbon-drawdown or the accessibility of climate-resilient shelter, they will have to transition to methods that are more compatible with industry standards.
For decades, prefabricated straw building systems have quietly persisted as a promising curio, but a contemporary surge of producers has engendered hope of a breakthrough. Savvy upstarts are synthesizing high-performance design with carbon sequestering materials through the development of straw filled, wood-framed Structural Insulated Panels (SIPs) that are quickly installed and compatible with conventional workflows. Straw-SIPs attempt to take the challenges of bale building and invert them: if stacking straw bales seems slow and unruly to the uninitiated, what could appear more efficient and accessible to the U.S. construction industry than a wood framed box? Amidst a climate emergency and a rapidly transforming landscape of design and construction, the moment may finally be ripe to establish straw within a new “carbon architecture” via prefabricated panels, bringing the performance benefits and climate solutions offered by straw building—and perhaps some of the essential ethos of the natural building movement—up to the scale of the crises at hand.
You can read the full article at www.thelaststraw.org
Especially for building multiple dwellings in a new subdivision, straw based structural-insulated panels could standardize straw bale construction. The system is uniform enough for efficient construction (especially important for housing developments), yet customizable enough to not be too “cookie cutter”. I’ve seen a straw bale SIP house plan on the DreamGreenHomes site that calls for three floors (well, technically two with a walkout basement), thus supposedly this system is suitable for multistorey construction.
Just about the only concern I have with straw based building systems is that straw is notoriously quick and easy to burn, thus whatever plaster gets used on the straw panels has to be fireproof, otherwise, the whole building becomes a Burning Man effigy!!
Actually, straw bale buildings are surprisingly resistant to fire, as shown at https://www.youtube.com/watch?v=PjM0yXF7sy8&t=10s
A 12 ft x 14 ft non-loadbearing wall constructed with 7.5 pcf rectangular wheat straw bales stacked in a running bond pattern, clad on each surface with 1″ of earthen-plaster successfully met the conditions of acceptance as outlined in ASTM Method E119-05a Fire Tests of Building Construction and Materials for a fire-resistance rating of 1-hour. A 10 ft x 10 ft non-loadbearing wall constructed with 7.5 pcf rectangular wheat straw bales stacked in a running bond pattern, clad on each surface with 17 GA stucco netting and 1″ of cement/stucco successfully met the conditions for a fire-resistance rating of 2-hours.
For the metric folks, measurements are as follows
A 3.7 m x 4 m non load-bearing wall constructed with 2124 cc clad on each surface with 25 mm of earthen plaster
A 3 m x 3 m non load-bearing wall constructed with 2124 cc clad in 25 mm