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Re: GSBN:Fwd: CASBA_ Pea Gravel



I love it when we get all fired up on these detail questions.

What to do in the sills has always been a concern of mine. Somebody
mentioned Roxul drainboard, which is what I used to use until it was
pointed out to me that it only drains when placed vertically. In a
horizontal application, it holds water really really well.

This year, I used two different materials that I really liked. David
mentioned that foam, while not always the most desirable product, has
qualities that suit this application. I saved up foam meat and
vegetable trays from home last winter, and then had enough to crumble
up and fill the sills for half of a large building. Not always do-
able, I agree, but it was free, provided insulation, but not that
solid foam "barrier" for those who worry about having some drainage.

The more practical material I used this year was zebra mussel shells.
I was impressed with the use of big mussel shells in Denmark. We
don't have them here, but we do have big troubles with invasive zebra
mussels, and their shells made a very good fill in the sills. Enough
trapped air to be decent insulation (better than pea gravel or sand),
but enough space to drain a bit of moisture and they won't allow any
wicking.

Of course, no code would have crumbled meat trays or zebra mussel
shells written in. But when I explained to the building official what
the intent was, he was quite amenable to both materials.

In terms of using that space for "drainage" I do embed those little
brick drains about every 4-8 feet on the exterior sill. Basically I
put one in where I have a joint between pieces of wood for the sill.
I've never seen or heard of anything weeping out of these, and don't
know how effective they would actually be for various amounts of
water, but for a couple of bucks I've been doing it just to feel better.

As an "aside" to this sill plate discussion, I have been tending
toward using foundation systems that are not monolithic under the
bales, i.e., two rows of earthbags or two rows of narrow concrete
blocks on a rubble trench or on a poured concrete footing. This
leaves between 4-12 inches of space in the centre of the wall
(depending on the material I'm using and bale size/orientation). This
wider space makes for great insulation without having to resort to
foam on the exterior of the foundation, and plenty of drainage should
that ever be necessary. Less concrete, too.

Thanks all for pitching in to these great discussions.

Chris