SB: Re: lateral bracing

["John Salmen" <terrain3@home.com>]

The question is whether the eng. designed the frame and bracing to be
self-supporting or whether the design includes the walls. If the design is
for the frame only ask the eng. to certify just the frame itself (that
should satisfy the building dept. - are you Islands trust?). It does not
sound that that is the case so if the frame design includes the exterior
wall stucco to provide lateral stability then you don't have much choice but
to follow the recommendations. The fact that the eng. is willing to accept
the cement skins tied together to provide that is pretty generous on their
part as it is difficult to model.

If you don't want to include the bale walls as part of the structural system
for code purposes - then you need to show that the bracing is sufficient and
would need to go back to the eng. to do that and it might require more
bracing - easier for them to do that in many ways and perhaps easier for
you.

As for earthquake stuff it is really hard to say what you want the building
to do -. In many ways I would prefer the structure to be independent of the
walls as I would not ideally like the p&b to put too much stress on the
walls (cracks) but in real life it is hard to create that kind of
independence. If you just have some crossbracing inside the walls under the
stucco in an earthquake this will flex like crazy and break the stucco skins
as well. The other alternative is to really make them work together in which
case you need to make those walls stiff - so you need to wire and stitch the
two skins together and do it well. You need to make the stucco crack in
predictable ways (control joints). Think of it like a piece of glass on the
hood of your car held down with glue in a few places. If it is one large
piece the vibrations will make it crack and lots of the pieces will fall
off. If it is lots of smaller pieces each glued down there won't be any
cracks and the pieces won't fall off. The glue is the wire so to speak
holding everything together

You could argue that the stucco bond to the straw is sufficient to hold
everything together and you would probably be right but it is not something
the eng. can rely on predictably over the entire surface of the building -
if there are pockets that did not bond they can cause a whole wall to fail -
the stucco mesh provides a little more certainty even if it may be
redundant.

John Salmen

----- Original Message -----
From: "ruth harding" <rharding@sfu.ca>
To: <strawbale@crest.org>
Sent: Monday, April 09, 2001 9:58 PM
Subject: SB: lateral bracing


> Hi everyone, me again.
> Had a few busy days, just finished installing the french doors in the
> bedroom, which had until now been closed off with plastic and bales
stacked
> to keep out as much draft as possible.  needless to say I have been
> cold.  I still don't have water, hydro or sewer but seem to be managing.
I
> am bring water up from a hose pipe to my cabin, have an extension cord
> plugged into the cabin which provides enough for worklights,
computer...and
> even the TV.
>
> Thanks everybody for all your input last month into the composting
> toilet.  The bucket is going very well!!  I didn't take to it, as you
know,
> and after a couple of weeks I found a portapotty for a good price.  After
> one day's use I went back to the bucket.  Those portapotties are a royal
> pain to empty!!
>
> So, here I am again asking for your indulgence and help.  During
> discussions I had with some of you a couple of months ago, we talked about
> sewing/not sewing, pinning/not pinning, wire/ no wire.  I have also read
> 'Serious'.
>
> I live in earthquake country, the west coast of BC.  I have a post and
beam
> with bale wraparound.  I chose not to sew, pin, or wire as my building
> isn't load bearing.  My designer has just emailed me today informing me
> again that she and the engineer are concerned I am doing none of the above
> as a post and beam house must have lateral bracing.  The only interior
> walls I have are the three bathroom walls, one of which is
> sheer.  Perimeter walls have cross bracing as well as anchoring into the
> perimeter wall.
>
> It seems my engineer wont sign off unless I sew and wire.
>
> Any input would be welcome.
>
> thanks,
>
> r
>
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