[Cob] bamboo ceiling in cob house

[Amanda Peck]

I used Cocoon (recycled cotton fiber treated for fireproofness) for the 
ceiling in the barn--pouring and raking, not blowing in this case, then 
putting a layer of sheathing over that so we could get up there, and stack 
boxes--not to mention paint the rafters with asphalt paint.  There's paint 
on the sheathing, but some breathability in the ceiling--unfinished pine 
boards nailed up, lots and lots of venting in the attic area.

http://www.greenstone.com/Links.asp

One of the places that really needs ventilation is your attic--both for 
temperature and humidity.  You also don't need for bits of insulation to 
come drifting down from your attic through the ceiling.

Or, could you use a nice thick layer of rice hulls?  More "all natural" 
pretty fireproof as is, still need a way to go from your bamboo ceiling to 
the insulation layer without having rice hulls falling into your morning 
cereal.  These guys seem to sell managable quantities of rice hulls--I 
haven't dealt with them.

http://www.ricehull.com/default.asp

And there's wool--makes a nice breathable insulation, especially if you have 
a sheep farmer nearby who will sell you low-grade fleeces.

If the "natural corn-based" insulation is Icynene--uh....

a) It MUST be professionally applied.  (not necessarily a bad idea--be very 
nice to get something done quickly and easily, but MUST is the operative 
word here)

b) End product is (probably) pretty benign, but at last report manufacturing 
wasn't.

c) If they're still using isocyanates as a blowing agent, they can be pretty 
nasty.  IF you are sensitive to the ones they used to use in automotive 
paint, ANY exposure could (not WILL, but COULD) cause a severe asthmatic 
attack.

It may even be that for most people Icynene is a good choice.  A friend of 
mine thinks it's the greatest stuff since Butternut Squash.  Not for me.  I 
spent a couple of years having to wear a respirator at work.  We were never 
sure that isocyanates were the problem, but....

.............
If infiltration is a problem, use a layer of light
clay , straw mixed with clay.  This should be fire
resistant as opposed to dry paper pulp. This has been
done for hundreds of years.  Normally over this
clay/straw layer
the thatch is applied.

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