Straw Bale Plaster Techniques: An Invitation to Discuss a New Idea

Written by Andrew Morrison

Andrew Morrison head shotI just got an email from a man named Greg who has a very interesting idea about plastering a bale house. His concept is a mix between plaster and concrete form work. I think there is merit in the idea and yet at the same time, wonder if the time savings would pan out. I do think that the straight finish of the wall would be impressive. I would like to hear from you all about this idea and what advantages or disadvantages you think it might have. Also, if any of you have a small project that could work as a test building, it would be cool to see how it fares in the “real world.” Here is the email he sent with the idea he proposes:

Hi Andrew,

Congratulations on your new web site! A while back I left a comment on the blog board and I guess it didn’t get through. I’ll try this email address. I posed a question for you about the feasibility of “pouring” the lime plaster skin on a bale wall using a vibrator to settle the plaster/straw fiber mix into the bale wall. I’m wondering if you make a form about 2ft. high and say 6 to 8 ft. long out of 1/4″ waterproofed Masonite and space it 1.5″ from the bales and use a 1″ vibrator to settle the mix as well as expel the air pockets whether it can cure and have a finished surface ready for a stain-coat? Imagine the labor and time this could save as well as the fine line of the wall which would appeal to the greater public? I’m wondering if you have considered this as a worthwhile technique? I’ll thank you in advance for your reply.

Best regards,


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9 Responses

  1. Hi everyone. Without having the experience of using lime plaster or strawbale construction I can only speculate about what kinds of challenges must be bridged to get a reliable “poured” lime plaster skin for a strawbale wall. My questions would be:
    1-How soon could the forms be removed?
    2-What would be the probable curing time for a 1.5″ thick skin?
    3-Would the skin be prone to cracking and if so, how could that be prevented?
    4-Could the forms be removed without pulling the plaster off the walls; wet or dry?
    5-Can a finish coat of lime be applied to the smooth surface of the skin after it’s dry?
    6-This method may or may not save time, but would it save labor? What do you think? Thanks!

  2. That’s patience! Holy Cow! I had completely forgotten about this question. Sorry.
    Having now reconnected with the concept, especially with the knowledge I’ve gained in the last year or so, I would not recommend this set up. I think the plaster would have a tendency to crack clear down to the straw, would be difficult to remove from the forms and would have a hard time holding the finish plaster due to the lack of “key” for the plaster to hold onto. In addition, the pressing back would be missed as well which really strengthens the plaster.

    Hopefully I’ll answer any future questions a LOT faster than this one. Once again, sorry for letting you slip through the cracks.

  3. Thanks Jan,

    I found this thread again (thought it had died!) I went to their site. It looks like they nail a temporary form on the frame uprights (2x4s?) pour in the plaster and add a new layer above that one and continue up. I don’t read French, so I couldn’t understand their explanation. If anyone else knows anymore please contact me at [email protected] Thanks!

  4. From their website they use a combination of 1 part Lime, 1 part cement, 3 parts sand and 4 parts sawdust. People commented on their use of cement so they had it laboratory tested. The vapour permeability came in between clay render and lime plaster. Very interesting indeed.

  5. I truly appreciate all your research Greg. Especially in view of the lack of responsiveness of Andrew and other readers. I am,very interested in this method. Can you provide sources aside from the Quebec group? Who tested the sawdust cement?

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