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Re: GSBN:More TLS #38, Roofs & Foundations
Forwarded for Barbara Jones, who is having email problems.
"the reality is that most codes,
builders and owners are going to choose some "form" of concrete foundation,
especially where frost is an issue. "
Frost isn't an issue in many types of foundation, as long as you don't use
concrete! 20th century building practice (and by this I definitely mean last
century's thinking) is so concrete brainwashed that ordinary people often
don't know that there are other ways and other materials to build with. Many
of these other methods have been around for several hundreds of years, at
least! And anyway, we're building with a flexible material that can stand a
bit of movement. Some of our 400 year old houses in England look very
appealing with their crookedy walls and are certainly stable, having been
built with those lovely flexible mortars, lime or clay and withstood not
only natural movement, but two world wars as well. I mean, how much control
over nature do we want?
I did some quick calculations (so they may not be deadly accurate) and found
that straw walls weigh 65% less than brick and block walls. Also the bearing
surface of this reduced weight is 450mm not 225mm ( or 18" not 9"). This
means we can be truly radical in our design of foundation, particularly for
the smaller (sustainable) type of self/owner built house.
I live in a stone built house with lime mortar joints. The walls are 18-20
inches thick and 6 inches below the ground level is a solid clay subsoil.
That's it! No artificial foundation at all except that the bottom course of
stone is wider than the wall by about 2 inches either side. And if that's
not enough, some of our cathedrals are built on rafts of wood over a marsh!
And have been there for hundreds of years too. Our Building Regulations
allow us to use any type of foundation as long as it poses no threat to
health and safety, and we can show it's effective.
Unfortunately, though, I think you're right and most clients/builders are
still going to choose concrete. We've a way to go with our education
programme. So if anyone has got some ideas within the concrete mould of how
to reduce it's use, lets hear it.
As for living roofs, I've long been against the traditional turf roof with
massive timbers and 6 inches of soil on top cos it's just not sustainable.
But I've designed and fitted Living roofs using smaller timber, with
corrugated iron, dpc, old carpet, 25mm of gravelly soil, and shallow rooted
plants. If you're interested in the technical drawing of it I'll happily
But maybe that wasn't your disagreement with it?
Anyway, be interested to hear your comments. If they're quick I may reply
but I'm away for 2 weeks from tomorrow.
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