re: strawbales (was re: natural building colloquium east (update))
13 may 2000
anthony matonak wrote:
>...i believe strawbale walls go up quick, but there's a lot of
>finish work with the plaster and such.
seems to me both sides could use more stiffness, and the outside needs
to be more weatherproof in places with wind-driven rain and snow and
freezing, and the inside could use some thermal mass for solar heating
and more smoothness for cleaning. and a pure bale wall needs to be
tensioned downwards to compact it vertically after it's built. which
leads me to wonder if bales inside concrete might work better, using
some sort of forms a la nearing to save labor and make the work easier.
>i've been quite intrigued by papercrete (newspaper pulp mixed with
>portland cement) as it doesn't seem to require so much finish work.
it would be nice to find a way to use paper without grinding it up.
paper mache' with a cement slurry for the inside and outside layers?
lay down sheets of newspaper over some form, then brush a flour paste
over them? sounds like it would take forever to build up a 4" wall
that way. with some sort of mastic/polyurethane coating? perhaps the
outside layer needs to be more permeable to water vapor than the
inside one, rob tom notwithstanding.
>> >...remove the bales from the inside through the doorway (which you
>> >should not have covered in concrete)...
>admittedly, this is most likely not the best way to go about doing
>this kind of thing. i've heard of a lot of other ways of going about
>putting up domes, even concrete ones, that don't rely on a stack of
maybe a bunch of weather balloons or epdm rubber bags (like bladder
tanks) all inflated under a large hair net? cover with paper mache
to protect the balloons, then ferrocement, with a flat hexagonal net
of tires and ropes over that, place bags of leaves for insulation,
and more ferrocement over that? then deflate the balloons.
>...has anyone made their own 'inflatable' dome forms similar to what
>those monolithic constructors folks do? i've been thinking that
>tyvek is pretty cheap and easy to work with.
typar (www.remay.com, 800-321-6271) is cheaper and tougher and darker,
charcoal on the unprinted side, and silvery on the other. it has a
lifetime guarantee... ("if typar housewrap is ever damaged by weather
or under any construction conditions, we'll replace it at no charge.
labor is not included.")
>for those who find cutting and sewing curves a challenge you could
>stitch (glue? melt?) together triangles in a geodesic pattern.
make up a bunch of 10'x10' pillowcases with hot melt glue? :-)
>> ...so, what do you think of the idea of burying bales of
>>mushroom hay (50 cents each?) inside the wall?
>i'm not really familiar with mushroom hay...
a farmer cuts hay and leaves it out to dry, but it rains before
he can bale it, so he bales it up damp and moldy and sells it
to mushroom producers.
>as i recall, most folks using hay or straw as insulation in their walls
>take care to seal it over with a fairly breathable surface of plaster
>or the like and they try to keep them dry. as long as this is done i
>don't see why it can't work just as well inside the wall as anywhere
these walls would be pretty dank inside initially. full of mold.
but the mold would be sealed inside by the concrete, and i guess
the walls would dry out eventually, so who cares? the hay would
just serve as a temporary internal concrete form, kinda like making
a hollow basement floor by covering soil with a thick layer of leaves
then plunging some holes in the leaves on a grid to make concrete
posts when a layer of concrete is added, as ken kern described.
the leaves eventually rot and settle to leave a hollow space and
some insulation under the floor. hmmm. the bales might shrink or
settle too, reducing their insulation value. maybe they should be
air-dried for a few months before using them...