[Greenbuilding] (no subject)

[Lawrence Lile]

Yes, XPS stands for Extruded Polystyrene.  It is a closed cell
insulation that doesn't mind moisture. Usually I've seen it in a blue
board, with a smooth surface, rather strong for a foam. 

There is also an Expanded Polystyrene, which has the disadvantage of not
being closed cell, so it can sop up moisture.  Usually it is a white
beadboard, and seems to be kind of fragile, with a mottled surface.  

XPS Extruded polystyrene is commonly used below grade.  It hates sun,
and termites can chomp through it, other than that it is pretty good
stuff, for plastic. 

Lawrence Lile, PE, LEED AP
Project Solutions Engineering
-----Original Message-----
From: Gary Viljoen [mailto:gary at humanworks.co.za] 
Sent: Friday, October 26, 2007 12:52 PM
To: Lawrence Lile
Subject: RE: [Greenbuilding] (no subject)

Thanks Lawrence,

Is XPS a polystyrene-based material?  Don't know how to source it here
in
South Africa.

Gary

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Lawrence
Lile
Sent: 26 October 2007 05:10 PM
To: greenbuilding at listserv.repp.org
Subject: Re: [Greenbuilding] (no subject)




 

>The straw will likely get damp, rot and provide no insulation, and
promote mold growth. Perhaps a foam, like polyisocynurate, or pumice or
perlite will be more effective.

-Rob Vadurro AIA, LEED AP


I'd agree, a non-rottable, less moisture sensitive insulation would be
best between masonry layers.  XPS (the blue stuff) would be my pick, but
polyisocyanurate (the foil stuff) would work fine, too.  XPS would allow
a little moisture transmission, which might be an asset, whereas
foil-faced is a moisture barrier, and might not allow things to dry out.


Top build with straw, you need to design the building from the ground up
to be a straw building - deep overhangs, straw up away from grade,
structure planned for a material that can shrink vertically.  Straw
isn't really very good insulation, but it is cheap so it is easy to buy
a two foot thick section of it.  A few inches of straw, IMHO, would not
be worth much.  

--Lawrence Lile


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