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Re: GSBN:Stone Veneer over Bales



Hello All,

It is intriguing how questions emerge in such a symbiotic way... This
one relating to the stone/brick veneer scenario.
A cement (concrete) board rain screen is being considered as an
option on a project in the works for central Halifax, this summer. It
seems this approach might present some of the same cavity/moisture
issues that you mention Rene.

The builder is  in the preliminary stages of designing  a three story
(residential/commercial) structure. He does not want to take any
chances with plaster failure on this first urban structure in this
area (hence the cement board option). Space is tight on the lot. The
project is confined to a rather limited footprint (30'x40').  Roof
overhangs present encroachment on adjacent properties, so they are
currently almost non existent. A basically flat, living roof is
proposed; shallow insulated slab on grade, with Geo-thermal.

It is a three story structure so  there would be a little more wind
flex than with a lower structure. He would like to stick with the
typical method of applying the plaster (clay slip+1.5" straw
reinforced earth plaster with 5% lime+lime plaster) directly to the
bales (no mesh  except where material transitions would recommend
it). Do you see any immediately obvious reasons not to do that i.e.
related in particular to the flex at three stories. . It is
surrounded by other city buildings, so unlikely to be constantly
hammered with driving rains. Rene, I believe you said there were
several 3-5 (??) storey buildings in your part of the world.

I can post sketches somewhere, if that would be helpful.

Thanks for your thoughts on this one!

kim



On 19-Mar-07, at 5:46 AM, Rene Dalmeijer wrote:

Bill,

I am reacting specifically to your last remark. Brick building is the
normal practice here including cavity walls for bigger more expensive
buildings stone is often used varying from the first few courses right
up to the first story. Even though the cavity is well ventilated it
tends to be very moist for a long time after rain. Ie meaning it is
not
home free as you suggest. In circumstances where this moisture is a
problem for instances where the inner wall is wood frame.

The practice for these cases, where the inner surface is not brick or
concrete, is now to make it very open, all butts are left open to
vastly improve ventilation in the cavity. This practice works best
with
slim (in height) bricks or stone and relatively narrow butt joints.
The
butts are not more then 1/8-3/16" and the course height is roughly
2-3"
This could work with a straw bale inners but I have no experience
besides this you will have to work out a way of anchoring the stone
veneer to the SB wall without creating problems in the SB plaster
surface.

I seriously prefer the fake stone scribing as suggested by others.
Which means you can see what is going on and is much closer to proven
practice.

Rene
On Mar 19, 2007, at 07:11, billc wrote:

At 6:32 PM -0700 3/18/07, Bob Bolles wrote:
The clients, architect and contractor have agreed on a Tuscany style
which will include a (concrete-based) "stone" veneer on the tower. I
have already vetoed the stone over the Bales, but I felt that it
would be best to run it past all of you just in the unlikely event
that someone had figured out a way to make stone cladding vapor
permeable (Yes, I know that's an oxymoron).


Perhaps you could treat the stone veneer as a sort of rain screen...
If the bales were plastered first to remove problems with fire and
vermin and such, then the stone could be laid up in front of it -
there's typically some gap between the stone and whatever's behind it
anyway.  At least, that's how they do it around here.  Add in
ventilation top and bottom, and you're home free.

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Kim Thompson
Straw Bale Projects
2699 Northwood Terrace
Halifax, Nova Scotia B3K 3S9
tel. 902-453-2429
e mail: shipharbour@...
www.naturalbuilding.ca

"Tradition and modernity are merely two sides of the same coin - and
must be dealt with simultaneously. Building cannot be a rigid dogma,
but a living, organic, ecological project. It is about continuity,
based on memory, common sense and experience and is the foundation of
invention."   Hasan Uddin Khan






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