[Strawbale] OSB or Not? (rendering versus sheeting) (dirk witvrouwen)
Max Vittrup Jensen
max at permalot...
Sun Dec 5 21:09:05 CET 2010
If you'll join the ESBG 2011, you'll see my approach, which I believe is
Earth plaster straight on vertical bales, sloped ceiling made from beams
with rough wooden boards with about 10 cm spacing to hold the bales
above; the boards covered with reeds below and plastered. (The bales are
also plastered on top, and ventilated below a vapor barrier, which again
is covered with roof tiles, after another ventilation space.
I don't usually consider myself 'conservative', but in this respect I
suppose I am; it's a fairly old proven approach. I'm still waiting to
hear from people who'd gone in and inspected OSB boards after 5-10 years
use above a kitchen (used by a family with children in a country with
plenty of wet and cold days outside). I'd like to see what's hidden
behind the nice plaster below and covered with straw etc. above.
Perhaps it's my simple pragmatic mind, however I can't grasp why the OSB
don't turn black with fungi...
I'm aware of a CZ-Austrian funded project which made such insulations
about 5 years ago, but apart from the architects showing they could do
it (and profiling themselves at conferences and media), then there's
never been a follow up research about the long term effect...
As we also reside in a forested part of Eastern Europe, where rough cut
wooden boards from local forests/mills are still significantly cheaper
(despite the export to Austria!!!), then it makes a lot more economical
sense than OSB.
There's been enough well articulated points about several other
downfalls to OSB, especially from Derryl and Rob Tom, so I'll simply
summarize it with Rob's statement: "OSB Stinks!"
[Which might be why, at the ESBG, you're only likely to find OSB used
for the composting toilets ;o) (We were given some which had been water
damaged in a flood)]
I read people objecting agains using sheet material instead of rendering the bales directly. The reasoning seems to be mainly relating fire protection and sealing air leaks. Yet, lot's of people use bales in their roofs. I'm assuming none of them would render the underside of these bales. So why do it for wall's if it's not done for the roof? Any thoughts?
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