[Strawbale] Welded wire mesh in Lime plaster

[John Swearingen]

If I understand you properly, Doug, you're putting little band-aids around,
extending eight inches into the plaster from wood (posts and plates). This
would serve to nominally tie the wooden structure to the plaster, and reduce
cracking at wood/plaster joints but does nothing to increase the strength of
the walls themselves.  A much better tie would be achieved using expanded
metal lath, since 8" of WWM doesn't have much for plaster to adhere/grab. To
achieve the strengths of the California test, one would need to have mesh
very securely attached (minimum each wire joint, 2" oc) on all four sides of
the wall.

You can see the tests at http://www.ecobuildnetwork.org/

Also as I recall, more fly ash may not always be better, and there may be a
point where the strength starts to go down.  I don't have the reference on
this, though.

John "Band Aid" Swearingen


John Swearingen
 SKILLFUL MEANS
design and construction
 www.skillful-means.com


-----Original Message-----
From: strawbale-bounces at listserv.repp.org
[mailto:strawbale-bounces at listserv.repp.org] On Behalf Of Leanne Rellstab
Sent: Tuesday, July 11, 2006 6:10 AM
To: SB List
Subject: [Strawbale] Welded wire mesh in Lime plaster


Doug wrote> I will put 2" square welded wire mesh 8" out from all wood
framing before plastering.

Howard wrote back: Sorry, why would you do that?  Of course, I have not seen
the plans so haven't a clue from what you've written what you intend.

Howard, 

I saw a post here on the forum that led me to a study done in California
that tested plasters with welded wire mesh and without. Since they live in
an earthquake area in California it was a very important study. The results
showed that properly stapling welded wire mesh to wood framing increased the
shear strength of the walls by about 400%. The study also showed that welded
wire mesh extending out further than 8" into the plaster did not increase
the strength by any significance. So I decided to put 14 gauge galvanized
welded wire mesh into my structure.  We do have a few 4.0-4.5 Richter scale
quakes around here about every 10-20 years.

Lime plaster definitely has some great properties and I can't wait to work
with it. We will use either some Fly Ash or Volcanic Ash as the pusalon
(sp?). I heard second hand from a renound lime plasterer that some tests
were done with fly ash and lime to a ratio of 80% fly ash and 20% lime with
some amazing strength results. Of course it was experimental so I wouldn't
try it on our house. We will probably use what is normally accepted for
pusalon.

Thanks for the reply
Doug

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