greenspree.ca at The Sietch

Having gone through bale building and seeing the problem areas involved with straw (admittedly some being self imposed) I have been thinking about developing a new green building technique that embodies all the positives of straw bales and none or few of it’s weaknesses. At the same time I wanted it to be simple enough cost effective enough to be built by any moderately handy family. My criteria for this new technique are:

1. Seasonability. Strawbale is an extremely seasonal material and being able to store hundreds of bales in the fall and winter to be able to build in nicer weather is not feasable for many people, ourselves included. This means that if you are in a cold climate and want to build a bale home, you automatically are placed in a time crunch from when you revieve the bales (ususally mid september here) and when cold weather makes baling and stuccoing difficult (can be as early as mid to late October). Compounding the cold is the dwindling daylight hours of this time of year, making working after business hours extremely difficult. For a new building technique to be truly successful it has to have no seasonal limitations.

2. Availability. Strawbale is great in this regard as it is available in just about every climate and locality of the world save desert and mountainous areas. Our bales came from fields a few miles from our house site which is also important as local building materials carry so much less embodied energy. The floor beams from our house were harvested and cut in our province as well. My new building technique has to have it’s main components available locally and in abundance.

3. Sustainability. Strawbale is also great for this as it is a rapidly renewable resource that is also a byproduct of producing our grains. In a sense it is post industrial recycling of a rapidly renewable resource. If no one wanted to use straw it would have to be disposed of in some other manner because it will still be produced. Another important green material stream is post consumer recycled material, or material no longer wanted by the public that needs to be disposed of. I want my building materials to be a combination of rapidly renewable and recycled materials.

4. Constructability. Straw bale building can be tricky. It can be quite hard to reshape bales especially in small award areas like around columns or at the corners of windows. Also the process of strawbale building invariably requires the use of a chainsaw. And finally, when building with strawbales your life will revolve around the weather forecast, tarps and keeping the straw dry! Some of these concerns can be mitagated by the type of bale construction used but it’s a trade-off. In-fill usually has less concern for moisture since you have a roof before the bales go in but it requires more cutting and retying. Loadbearing bales go up fast with little modification but require a long stretch of good weather while the bales are stacked and the roof built. I want the next building I build to be easily constructed with flexible materials that are also weather resistant.

5. Livability. Strawbale building is extremely accessible and livable to almost anyone. Some techniques like earth ships require a bit of adjustment in lifestyle to get used to. For all intents and purposes, earth ships are live cave dwelling and some people are fine with that. Some people aren’t! Also I’d like to find a building method that lends itself to a multitude of architectural styles.

6. Efficiency. Yes, this criteria is a big one and has to do with how efficient the technique is in material usage and also how will it holds energy/heat. I put material usage and thermal resistance in the same category because any technique can be super thermal efficient with the addition of enough material. Conventional framing techniques with double offset exterior walls could probably outperform straw bale easily but would cost a fortune both monetarily and with embodied energy. Straw is a pretty good balance of the two and pretty hard to beat so any new technique would face quite a challenge in this category.

7. Elementality. This is a criteria that is very personal and hard to quantify. One of the reasons strawbale appealed to me was it’s elemental nature. It’s simply unprocessed cellulose insulation in bale form. It doesn’t require processing or added energy aside from the baling process and doesn’t contain any man made or toxic elements. Cob, stackwall or cordwood, stonework, rammed earth and log homes all have that same elementality that I am attracted to.

So after identifying my criteria I started looking at existing techniques and methods and weighing them against each other and the criteria. The result is a theoretical hybrid timber framed modified fidobe block structure with a papercrete foundation and earthen stucco. The use of localing harvested and milled timbers as the main structure is a comfortable building skeleton for most builders to work with and is inexpensive and fast. A modified form of fidobe using paper(or modified papercrete using clay as the binder) using local clay and paper is both cheap and available year round and should be made easily with a tow behind mixer. The use of papercrete in the floor provides a strong floor surface that eliminates the need for underslab insulation as the floor itself acts like a big block of insulation. Clay stucco is easily applied and adheres well to fidobe and can be protected with locally sourced silicate paints.

I hope to attempt a test structure of this sort next year after we have a chance to rest from building our house! I think it may be a good way to build a small workshop and storage building, perhaps with some solar space heaters and a small wood stove. The only area I am stuck on, and have been with every building style I examined was with the roof and how to achieve a strong, durable, locally sourced roofing material short of eastern cedar shakes or making my own clay roof tiles. I am not overly enthusiastic about wood shakes for a roofing material as they are fussy and require painstaking care when installed on a roof application. Clay tile does appeal to me in ways but suggests a LOT of work to produce! Steel is easy, durable and recycled/recyclable but hardly local. Asphalt is definitely out for obvious petro-chemically reasons, living roofs require membranes made from synthetic materials and/or imported rubber products.

So my research must continue, I am hopeful that some readers here will toss out some ideas that I haven’t thought of.