[Cob] more cob floor debates

[Tys Sniffen]

Barbara,

Well, I think we have a really good site drainage situation, but I don't
know the 'sucking' properties of the untouched subsoil.  On our western
facing slight slope at 2000 ft above sea level in northern California very
near the top of the hill, our anti-water set up includes:
- urbanite mortared retaining wall with 4-6 inches of gravel behind it, weep
holes, 4in perforated pipe going to daylight on both ends underneath that
- about a 3 foot gap between the retaining wall and the wall of the house
which is under the eaves of the roof
- perforated pipe under the bond beam/stem wall that also goes to daylight
- more pipe along the north, bermed in side 
- about 3 feet of overhanging eaves around the entire house
- there's a bump of soil above the house that pushes away surface water also
- it's a 3 level house (one or two steps between levels) and there's close
to 20 inches of drain rock (3/4") inside the stem wall, -BUT, at the top,
uphill side, there's maybe some spots where the drain rock only goes down 3
inches.  Mostly at that shallow end it's 4 or more, but that's my worry
spot. 

So, that's why we're debating the vapor barrier. Those damn 3" spots. 

Tys


Message: 1
Date: Thu, 16 Apr 2009 22:34:22 -0700
From: Barbara Roemer <roemiller4 at gmail.com>
Subject: [Cob] more cob floor debates
To: coblist at deatech.com
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	<6e41aaf40904162234j744a7b47he8a4e934ba7a2ef6 at mail.gmail.com>
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Hi Tys,

I think the question to start with is what is your site drainage like?  We
have an earthen floor over a lot of scoria - like 14", with no vapor
barrier.  BUT the site drainage is terrible - we have to correct it with a
curtain drain (we just moved into a renovated garage and then added the
bathroom with an earthen floor).  Even with all that lava rock, we still
have some expansion and contraction, seasonally, because of the amount of
water that runs through the rock.

If I had it to do again, I would definitely isolate the earthen floor from
what lies beneath it.  I wanted an earth-coupled floor for ill-articulated,
sort of amorphous reasons - silly, given the length (or depth) we went to to
assure there was NO earth coupling, and given the absorptive properties of
earth.

Barbara

Tys wrote:

>
>
> Questions: Anyone out there with cob floors ever have any trouble with
> moisture coming up?  If so, how much gravel is underneath? Anyone put a
> vapor barrier under their floor? If so, have you had any trouble with it?
>