[GSBN] School built in Nepal - Seek for advise

[Matts Myhrman]

Wondering if a lime wash would delete the spots permanently.  Easy to test
in a small area.  Would also lighten up the space.

Matts (If all else fails, whitewash it) Myhrman at (Still) Out On Bale.


On Thu, Jun 19, 2014 at 4:57 PM, Graeme North <graeme at ecodesign.co.nz>
wrote:

> Hi James
>
> The spots look like a very typical interaction that sometimes happens
> between wet clay and organic matter - and is most likely the result of a
> fermentation process in action.
> It can take months for the stains that can result to develop as moisture
> migrates through the material, as you have found out. The end result from
> fermentation usually toughens up the wall material, but if uneven
> fermentation takes place within the wall, will typically cause staining. It
> appears that it may be related to the position of the bamboo that is
> nearest the surface of the wall, i.e. where the daub is thinnest, for some
> reason that eludes me.
> It is not harmful but can be persistent, and can look disfiguring.
> Not a very nice idea, but bleach can sometimes remove these marks.
>
> I think that the very worst thing would be to put a cement based anything
> on the interior of these walls - that will stop it breathing, trap moisture
> within the wall, and could lead to all sorts of problems, esp if the spots
> are related to ongoing moisture migration of any kind within the wall.  I
> am not sure of the traditional houses are now typically rendered on the
> outside with cement paint, but if they are not, and do not get spots on
> them, then this may point to the cause and a solution too, as cement based
> paint will act as a moisture barrier and hold moisture within the walls.
>
> The traditional render sounds good to me. If it cracks the addition of
> more aggregates should help, i.e.  adding in more rice husks and fibre, or
> sand if any is available.
> After 6 weeks the plaster should have fermented nicely and give a nice
> even colour!
>
> Maybe this may help
>
>
> Graeme
> Graeme North Architects
> 49 Matthew Road
> RD1
> Warkworth 0981
> tel/fax +64 (0)9 4259305
>
> www.ecodesign.co.nz
>
>
>
>
> On 18/06/2014, at 8:43 AM, James's <james.henderson8 at bigpond.com> wrote:
>
> Does anyone have any ideas for Sona?
> Thanks James
>
> Sent from my iPad
>
> Begin forwarded message:
>
> *From:* Sona Huberova <sonahuberova at yahoo.com>
> *Date:* 16 June 2014 9:47:39 AM AEST
> *To:* James Henderson <james.henderson8 at bigpond.com>
> *Subject:* *School built in Nepal - Seek for advise*
> *Reply-To:* Sona Huberova <sonahuberova at yahoo.com>
>
> Dear James,
>
> my names is Sonia and we met at the EBAA conference last year, we are the
> couple with the school in Nepal. I have to organize fixing some defects on
> this first building now and would like to ask for your opinion in one
> particular matter. I just started to read your book so I thought that you
> may be able to help us.
>
> As you may remember, the school is built with bamboo frame and wattle and
> daub walls, weaved and plastered from two sides. After a couple months,
> spots appeared on the inside of the walls, you can see in the attachment.
> The spots are not seen on the outside, but we think that it is because the
> facades were painted with cement-based paints at the end of construction,
> which did not happen in the interiors.
>
> We are planning to fix the spots by painting the interiors with similar
> paint, although I am not sure it will solve it for good. But we are puzzled
> why did the spots appear in the same place. We let the villagers to mix and
> render the walls in their traditional way, so the mixture is as follows:
>
> 3 parts of soil (half in half mixed from two soils, one more clayey, one
> less)
> 1 part of rice husks
> 1 part forest grass finelly chopped
> 1 part cow/buffalo dung
>
> The mixture has been left to rest for six weeks or more. We were told that
> this is the traditional way to render, and the mixture indeed was very
> strong after drying, alhough cracked a lot and two more coats were needed
> to finish it. I am not sure what sort of mixture they used for the final
> layers, but it would againg be just a combination ot the above mentioned.
>
> Some of the walls were then filled with loose soil, but we abandonned this
> so not all of them are. the spots appear on the filled one as well as on
> the empty ones.
>
> We are surprised at finding the spots as none of the local houses,
> rendered in this traditinal way have this problem.
>
> Would you have an idea what may have caused it? Have you ever encountered
> or heard of this sort of spotting?
>
> Bamboo elements were pressure-treated with solution of Acid Boric and
> Borax, do you think that may be the problem?
>
> We are planning to build more of those school buildings in Nepal based on
> a standardized project, so we will need to avoid the defects and their
> causes in future.
>
> Sorry for bothering you with it and I would understand if you did not have
> time to answer to me.
>
> Kind regards
>
> Sona Huberova
> +61 466 482 682
> meemARCHITECTURE
> www.meemarchitecture.org
>
>
>
> <Classroom walls_1.jpg>
>
> <Classroom walls_2.jpg>
>
> <Classroom walls_3.jpg>
>
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