Straw-bale Research Building at the University of Manitoba

Eco-building



Straw-bale Research Building at U of M



Straw-bale building at the U of M campus, exposed bale wall protected from rain during construction (Photo: Om Joshi) Two-string straw-bales (35"x18"x14") used in construction (Photo: Om Joshi)

A Researchable Building:

The straw-bale building under construction on the U of M campus is worth $280,000 and arguably the largest straw-bale building anywhere. 
Building style:             Post-frame structure with straw-bale as infill

Area:                           4,200 sq. ft. 

In this type of construction, the weight of the roof is carried by wood framework. It relies on already established structural concepts. However, this method requires a higher level of carpentry skills and more timber than a load-bearing design. Thus, a relatively higher cost and environmental implications are attached to this type of construction (Amazon Nails, 2001). 

This building uses approximately 1500 bales as an infill and insulating material. The straw bales in the walls are stacked in a manner similar to bricks or concrete blocks, in a running bond. These bales are made of wheat straw that is harvested in the fields near Beausejour, Manitoba (Dick, 2004). They measure approximately 35in. x18in. x14in. (l x w x h). It is necessary that the bales should be dry, well compacted with tight strings, be of a uniform size and contain virtually no seed heads. Moisture content in the bales should not exceed 15 percent. 

Foundation:
The foundation of this post-frame building consists of pressure-treated, nail-laminated posts buried in ground. It is an excellent example of low-impact pier foundation. Some of its advantages are (Amazon Nails, 2001), 

  • It is low cost. A series of posts is much less expensive than strip foundations, which require much more soil excavation.
  • It has a much lower impact on the environment.
  • It is relatively easy to construct.
  • Some of the parts could be recycled at the end of its life. 
For such a framed construction, frames are often built off-site and assembled after the foundation is finished. All framing is done before the straw-bale is placed. The roof is constructed with felt or tarpaulin and battens to function as a waterproof shelter. The walls will be finished with stucco. This is the most labour intensive process in the construction period.
Building plan showing doors, monitoring system.
Left: walls are up to 20 inches thick. Right: Wide eves to protect wall. Photos: T. Pearce 2006
Corner detail (Photo: Om Joshi)

Construction phase January 2004. (Source: Kris Dick 2004)

Wall and window frame (Photo: Om Joshi)
Typical wall section: Source: Information Guide to Straw Bale Building (www.strawbalesfuture.org)
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