The Straw Bale Roundhouse – Photo Blog

One of the most exciting projects we took on this year, in 2013, was the Straw Bale Roundhouse at Woodland West, just outside Millarville, in Southern Alberta. Our workshop hosts, Margit & Drew McNaughton, share in our vision of creating spaces that are inviting, a sensual experience to build, and bring community together. They were really excited to host our first week-long residential workshop, and they were certainly instrumental in making it a successful week. We spent a lot of time getting the site in order, making sure the rubble trench foundation was working, testing clay & earthen plaster recipes, and last minute (of course) design changes that were required to accommodate rectangle bales into such an organic structure.

What a week! We had an amazing group of 15 students. During workshop we accomplished the following:

  • Covered the fundamentals of building with straw bales, using an alternative, low embodied energy foundation
  • Mixed, filled, and packed two courses of stabilized earth bags that serve as the stem wall
  • Put up five courses of straw bales, including trimming, stuffing, and shaping to get them ready for plastering
  • Installed four windows and a little round ‘hobbit’ door
  • Mostly finished the base coat plaster on the outside, and got a good start on the interior. 

To get the little building ready for winter, we spent a few follow up days to complete the base coat plasters inside & out. And to wrap up, we gathered a core of the straw bale workshop participants to apply mid-coat plasters to the interior & exterior. We thought we’d share a few photos from the whole process.

General Specifications

Roundwood Frame & Reciprocal Roof:

  • Wood was harvested from the host’s property, Woodland West
  • There are 13 sections (in order to have balance & fulfill the Golden Mean), though none of the posts are at the same height, nor were the sections equal, which made for a slower process when it came time to stack the bales, but resulted in a most beautiful and unique structure
  • Roof is a self-supporting (no central post) reciprocating roundwood roof, which is in the process of being finished with cedar shakes

Earthbags:

  • About 20 inches wide one tamped out, poly bags filled with local subsoil, to accommodate 18” of straw bale with enough width leftover to act as a plaster stop
  • Stabilized with 6% cement to ensure enough stability & longevity
  • The exterior of the earthbags were insulated with several inches of EPS, covered with chicken wire and waiting to be finished

Straw Bales:

  • Stacked on flat
  • Running bond in each section; notched top bale to fit securely around top post
  • 1X2 vertical tie strips were used to provide lateral support to the walls. These are run from the top of the wall to the bottom, one on the inside and one on the outside parallel to one another and sewn together through the wall with bale twine. They are fastened at the bottom of the wall to the earthbag stem wall AND the top of the wall to the to the roof decking

Plasters:

  • All earthen plasters were made with clay from a nearby construction site (diverting a product that would otherwise go to the landfill!)
  • Dirt Craft’s base coat: fibre rich recipe good for filling out the wall and getting a good supportive layer to add on to. Approx. recipe is something like 1 sand : 3 clay : 5 chopped straw
  • Mid-coat: more of a ‘standard’ earthen plaster mix, something like 2 sand : 1 clay
  • Outside has been painted with water glass to provide exceptional water and erosion proofing, all without impacting the vapour permeability necessary (read more about that here) to ensure a healthy straw bale wall

Finishing Details (look forward to seeing some of the list below happen in 2014!)

 

 

  

                          

 

                              

 

  

japanese plaster technique base coat earthen plaster straw bale

  

 

 

 

 

 

 

 

    

   

 

 

 

applying earthen plaster mid coat to interior straw bale

  

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