A Trial in Load Bearing Design, Dealing with Hard-Pan Clay and Lessons in Being Adaptable
For five days in August we were hired to lead a work party to erect the walls for a straw bale Temple, just outside of Sherwood Park, Alberta. It all came together on a rather short timeline, with many efforts converging to make it happen.
The Temple itself is to be dedicated to the preservation and conservation of the lands in Alberta and the people who strive to protect them. The intent is to have a sacred space that will always have ‘the home fires burning’. There will be someone tending the fires every day, with open Temple hours, for people to come and retreat, spend some quiet time in nature, reconnect, and send their own desires and intentions for healing out to the world. This space is to be available for people of all faiths, spiritual beliefs and religions, as a global healing temple for all.
With a vision and intention for the space, the owners of the land where the Temple is being built set out to build the foundation, necessary framing, roof, door and window bucks, and ready the site to receive the straw bales and plasters that we would be working on during the work party. These are creative, hard working folk, but as they worked, they veered away from this plan that we had worked out. A few short days before we were to arrive onsite, we discovered that contrary to the original plan, there was actually going to be very limited framing within the structure, that there would be no roof in place, and that the straw bale walls and plaster system would actually be bearing most of the weight of the roof when it was built (as well as deal with additional loads from snow, or wind).
The work that we were to be doing went from being an infill wall system to load bearing design!
In load bearing design, the bales combined with the plaster create a stress skin panel that takes both the live and dead load that a building may experience through different seasons, or storm, earthquake or other stresses that a building may face, including the weight of the roof. The forces that are put on the plasters are high, and therefore the plasters require a high degree of compressive strength. This is why you will mostly see clay plasters paired with load bearing designs in places where additional loading from, say, snow (places like Arizona, Mexico, etc.) is low or unlikely. Even then, and certainly in places where additional loading strength is needed, whether from snow, high winds, earthquakes, etc), it is common to see reinforced cement-lime stucco used with load bearing designs.
In this case, there were some elements of framing, but there was still a lot bearing down on the bales and plasters themselves. After much discussion, the owners were still interested in pursing a clay base plaster system, and were well aware of the potential challenges the structure could face. It should be noted that the owners of the Temple are engineers, and understand the risks involved, and we’ve made a contingency plan in the event that any problems come to light. This is also an out building, and will not be housing people on a regular basis. It is not recommended to experiment in this way on one’s house!
The Work Party
For the five days in August that we were on site we lead a work party to erect the walls for the straw bale Temple and get the initial plaster on. It all came together on a very short timeline, with many efforts converging to make it happen. We asked a lot from our participants, and everyone contributed everything they could offer. As each person left, they commented on how they had learned more than they’d expected, that their eyes have been opened to the possibilities of natural building, and that though this building had presented some challenges, they were thrilled to be able to be part of the problem solving and solution making efforts. We were thrilled to work with you all.
We arrived at the building site just before the sun went down and took a quick look around. Of course, our minds were occupied with what the next day was going to look like, and how the build was going to come together in the morning, but we couldn’t help but notice the absolute sticky clay that was already gumming up our boots.We saw a pile of incredibly chunky, heavy clay that had been used to help level the screw pile foundation, and was not exactly representative of the sample that we’d received.
When we did get a chance to asses the material in daylight, it was revealed that the site had about 6 inches of topsoil, and then solid, solid clay clay. Near impossible to even dig by hand, it was looking like it would be an ugly mess to try to extract into a workable material to make plaster.
Luckily, not only was there a skid steer on site, but an old rototiller as well. The first thing we did was to dig up a fresh pile of clay, and avoid the stuff that had been sitting in the sun and rain. Often, unless you’re digging after a big rainstorm, clay is at a very good moisture consistency to process right when it comes out of the ground. Using the skid steer, we piled the clay and then ran the bucket back and forth to break up the biggest chunks. Then we followed up with the rototiller. The pile had become loose and pliable, and fell easily through the 1/2” screen. Because of the even consistency of the clay, we were able to discard any of the un-screenable lumps without compromising clay quality.
The Wrap Up for Winter
For this season, the Temple has the base coat of plaster on, as well as the roof, which will get it through the winter. The plan is to apply the second coat of plaster to the walls, as well as a final coat of water glass paint to the exterior, and install and earthen floor in the spring, to bring this beautiful building closer to completion.