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RE: GSBN: Lime plaster problems

I liked the Japanese approach which made fairly sharp pock marks to key
the plaster. The failed skin is all to easy with a smooth wall.

You might also find a useful article or two in the Getty biblio

David A. Bainbridge
Associate Professor, Sustainable Management
Marshall Goldsmith School of Management
Business & Management Division
Alliant International University
10455 Pomerado Road
San Diego, CA 92131
(858) 635-4616     (858) 635 4528 fax
 WEB: marshallgoldsmith.alliant.edu
-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of John
Sent: Wednesday, September 26, 2007 11:58 AM
Subject: Re: GSBN: Lime plaster problems


It seems to me that major problems were weather related, the drying wind
freezing. You don't say just how smooth the earth plaster was before
was applied. If it's a porous material the lime would be able to adhere
without scarfing.

The lime plaster needs to be removed in any case, and you could no doubt
some teenagers to deface the surface of the earth plaster for a small
Then try again in warm weather, or move the building south to a warmer


On 9/26/07, Andy Horn andy@... wrote:
> Dear all
> Dear all
> I know this is not strictly a SB question, but rather one of lime
> ...but really could do with some experienced input.
> I recently was involved in the building of a large 2 storey mud brick
> school
> classroom...in a rural part of the country. To help protect the walls
> applied an earth plaster followed by a coat of lime plaster on the
> side. We used a hydrated lime and added plaster sand together with a
> amount of the adobe soil to the mix. We applied the plaster and as
soon as
> it had set applied a colour "fresco" wash for a gorgeous looking
> We
> also rewet the wall continuously for good curing, but were not
> with
> proper scaffolds and drop sheets to cover the walls from the sun and
> ...and made do with a large sail that was precariously positioned
> our
> 2 scaffold towers.
> While applying the plaster, we ran into a number of difficulties. The
> suddenly picked up and was drying the plaster out excessively quickly,
> leading to much cracking. So we had to rework the cracked surfaces to
> the cracks out. On the first morning after applying the plaster the
> weather
> turned at night and brought frost...2 months ahead of when it is
> expected! There were sheets of ice in the water buckets that morning!
> A few weeks later, it turned out there were major problems with the
> plaster
> delaminating from the walls, (see below).
> The supervising architect wants to know what to do....and is being
> to strip off the existing plaster and attach a chicken mesh around the
> structure and reapply the lime plaster. I am not keen using the
> mesh....don't think it is needed if there is no cement in the plaster.
> Also
> it can rust and will be expensive. The whole idea with the project was
> train the locals in simple inexpensive methods they can employ on
> own
> structures.
> If anyone has some insights to share or advice as to how we can do it
> better, I would most appreciate your inputs. Maybe we should have done
> coats....The base earth plaster coat was due to a miscommunication on
> was not provided with a proper key....and we were not sure how to
> one with the earth plaster already hardened, without damaging /
> its strength. Any ideas for how best to do this....drill holes, angle
> grind,
> soften with water and saw cuts...???
> I also have pictures I can email to you directly if you want to get a
> better
> idea of the problem we are facing
> Your inputs would be much appreciated
> Kind regards
> Andy Horn
> --------
> Hi Andy
> Here are some photos taken earlier today of Block B.
> Owen, Dave Osborn &amp; I all agree that there doesn't appear to have been
> proper bond between the lime plaster and the earth plaster. The
> treatment of the substrate appears to be too smooth for bonding to
> place. The bad news is that there are large 'hollow' areas - at least
> of
> the plastered surface. We all agreed that a good solution would be to
> strip
> the plaster off and nail/staple a layer chicken wire onto the
> before replastering. I guess that we should have scratched the surface
> deeper before we applied the plaster. Weather conditions could also
> played a role. The lime plaster layer is approximately 10mm thick and
> appears to be strong.
> Please give me your thoughts on this.
> Regards
> Steve
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John Swearingen
Skillful Means, Inc.
Design and Construction

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