CLAVERACK-Thirty-five individuals from around the U.S. and from Slovenia, Ireland and Russia attended a recent straw bale building workshop on Snydertown Road. Ranging in age from 15 to over 60, they paid $800 to camp on the property from October 9 to 15 to learn the building process from straw bale guru Andrew Morrison, an expert in the field who teaches 10 similar workshops each year to student builders at locations as diverse as North Dakota and Perth, Australia.
Mr. Morrison who started his straw bale building career in Oregon, is a Hampshire College graduate and a former geo-technical engineer who headed a drill team that sampled soils for siting new construction. His experience with conventional, large scale development and the waste it entails led him to look for alternative techniques, a search that drew him to straw bale construction. After producing a host of videos on the subject, he will release his first book this fall.
Full and speedy enrollment in Mr. Morrison’s workshops may indicate that interest in the technique is on the rise. The fact that a straw bale home won the 2012 Houses Award from Fine Homebuilding magazine for Best New Home of the year indicates rising acceptance among conventional housing groups.
Straw bale buildings benefit from the thick straw walls that provide structural building blocks and impressive insulation with an R-value of 30 to 45, while a conventional wood frame house has an R-value of 15 to 20. A straw bale house uses around 75% less energy than a conventional house. The bales are not flammable, nor do they offer food value to pests like mice or termites.
Straw bale building has come a long way in just a few years, and Mr. Morrison has devised a system that eliminates the use of metal rebar, which he says attracts moisture, in favor of nails in wood placed on top of a cement foundation that snags the bottom row of the bales. Since moisture can lead to rot, his system is designed to let bales breathe. The bales are tested for moisture content before they are used.
The system relies on compression of the bales inside an open plywood box attached to the wood structure. Steel mesh sheets attached over the bales and are stapled into the wood structure inside and out. The mesh sheets are later connected, sewn with twine run through the straw walls with a bailing needle that provides strength and extra structure to support the plaster that will form the surface of the walls.
Mr. Morrison favors a homemade limestone plaster over cement for its ability to allow moisture to escape from the bales.
Before we started, the building had a polygonal, post and beam frame, and a cement foundation poured over a radiant heat system. Our first tasks involved adding wood to the structure to create bale stops and to allow for the attachment of plaster lathe.
The bales used in this project came from nearby Holmquest Farms and were rye grass cut in July. We learned how to shape bales by notching and retying them with a special slip knot and how to shape them so that they bond well with neighboring bales by trimming their ends with a chain saw. We learned that walls become smoother and straighter after you pound on them with a tamp, and we used Weedeaters to smooth the finished walls.
We nailed flashing around the foundation, reinforced door jams, installed windows, ran wiring inside the straw walls, and wrestled the straw into place using levels.
The hardest part of the process turned out to be wrestling the final top bale into position.
“Hire someone young and strong to do it,” advised Mr. Morrison.
A smooth masonite sheet inserted below the top bales to reduce friction and a car jack helped some.
On the afternoon of the last day of the workshop, it was time to plaster the exterior with the homemade limestone plaster. The base coat we applied is the first of three layers. In a few hours our crew of 35 covered 80% of the exterior walls. They troweled in each new batch of plaster as quickly as it could be mixed. With some 30 people working on one 600-square-foot building, it was hard to find a place to work.
Many participants returned home with elaborate video and photographic records of the process, that should prove helpful when they get around to constructing their own homes. Some who had arrived with plans already drawn out looked at their designs with fresh eyes.
Jim and Sarah, Transcendental Meditation instructors from New York City, remained firm in their resolve to use locally sourced materials for the house they plan to build in Fairfield, IA. Instead of a cement foundation, they plan to conserve resources and save money by creating an earthen floor on top of a gravel foundation.
Paula, an engineer who owns land in Greene County, has decided to use custom prefabricated straw bale walls. Another participant plans to use dry stacked cement blocks for the half of his house that will sit against an excavated hillside and straw bales for the rest.
Mike, a retiree from Galway Ireland who had hoped to learn techniques for building that were inexpensive enough to employ in building homes for the poor in South America went away disappointed. The house, designed to look and feel like a yurt that will be used as a kindergarten for 14 toddlers turned out to be extremely labor intensive and may finally cost between $60,000 and $100,000.
Most workshop participants returned home with their straw bale dreams intact in spite of their encounters with the daunting reality of a demanding process. Even those who may have changed their minds about whether this building technique was right for them spent an invigorating week working outdoors with like minded cohorts.
By four o’clock on Monday many tents had come down and people started to head home. Mr. Morrison headed for New York City to catch a plane home to Colorado and his first design workshop for straw bale homes that would be held in Denver the following weekend.
For more information go to: StrawBale.com.