[GSBN] Wall Heights - Larger & Multi-storey Straw Bale buildings

[Derek Stearns Roff]

I'm not sure where the 6:1 height to width ratio came from, and I protest it whenever I see it.  While some experienced SB leaders and advocates believe in this figure, others do not.  We have laboratory testing, historical examples, and post-1990 loadbearing buildings which exceed this ratio, often by a significant margin.  All of these give me confidence that we can safely build strawbale walls with higher ratios.  Of course, buildings in seismic areas require greater safety margins.  On the other hand, infill designs should be less critical than loadbearing.

Derek

On Apr 5, 2013, at 2:24 PM, John Glassford wrote:

G ' day Andy

We have built a few large straw bale buildings and here are the links:

Lethbridge Winery<http://glassford.com.au/main/projects-menu/lethbridge-winery/>  6.0 metres high load bearing using 2.4m x 900mm x 860mm wheat straw bales.  Tie downs high tensile fencing wire and cement render.

Nulawala Community Hall<http://glassford.com.au/main/projects-menu/nulawala-community-hall-fairfield-sydney/>  4.2 m high Load bearing jumbo bales 2.4m x 900mm x 600 mm jumbo bales.  Tie downs all thread rod at 1.8 metre centres.  Lime render.

Valhalla Winery<http://glassford.com.au/main/projects-menu/valhalla-winery/>  4.2 m hign Load bearing jumbo bales 2.4 m x 900mm x 600 mm all thread tie downs lime render

Steiner School Community Hall<http://glassford.com.au/main/?s=steiner+school&x=8&y=6> 5.8 m high Small bales steel frame in-fill, 16 mm tie downs all thread lime render.

I hope that the links work for you if not let me know and I will send you some photos to your email address.

I see no problems with in-fill to just about any height all depends on the frame.  I see no point in following the 6:1 ratio for in-fill.

Load bearing jumbo bales we have been as high as 6.0 metres and if you include the gable ends up to 9.0 metres high with no problems.  As for standard bales I also see no real problems with going to 2 story high load bearing as long as there is a middle plate involved for pre-compression and stability.

As for renders we prefer lime and sand.  Our earthen renders are also working very very well and we do not use cement renders at all.  We spray our renders on and they penetrate the bales and create a very good key.  We also mesh the second coat with render mesh:

Mesh into render<http://glassford.com.au/main/wp-content/uploads/2009/02/14-valhalla-mesh-on.jpg>

We have not done any studies on the height to width ratio just used common sense and a good structural engineer and we base our arguments on the school of hard knocks.

Just about to leave for Gosford to complete the Steiner School final coat of lime render aprox 1,000 square metres will post photos to our web site.

Feel free to use any of the photos in your presentation.  Susan and I will be back in Cape Town in May 2015 hope to catch up with you then.

Kind regards

Susan and John Glassford
Huff 'n' Puff Constructions
http://www.glassford.com.au<http://www.glassford.com.au/>
61 2 6927 6027
In Australia (02) 6927 6027

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____________________________

Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


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