RE: [GBlist] OSB

["Ralph Bicknese" <ralph.bicknese@christnerinc.com>]

OSB is about as water tolerant as CDX plywood.  Both will swell a little if
wet for a while and will swell more the more often they are wet and the
longer they are kept wet.  I am not sure which performs better in wet
weather.  Both CDX and OSB use glues that do not contain added formaldehyde
and therefore any surfaces exposed inside do not create a voc problem.

For even wetter applications there is marine grade plywood.  Another option
for other outdoor uses is called MDO (Medium Density Overlay) plywood.  It
has a paper based face to create a smooth surface for painting.  It must be
painted to preserve the face in wet weather but once painted lasts a long
time.  It is frequently used for painted signs.

Cheers,
Ralph Bicknese

-----Original Message-----
From: Alan Courtright [mailto:acourtri@krl.org]
Sent: Tuesday, October 29, 2002 2:16 PM
To: greenbuilding@crest.org
Subject: [GBlist] OSB


Lately there's been an opinion expressed that if OSB gets wet, it'll turn
to mush.

But here on the we(s)t side of Washington (which actually gets less rain
than New York City) people build all the time using OSB, including for
roof underlayment, and seem to feel no need to cover the stuff up if it's
raining during the construction process.

Is there no equivalent to CDX in OSB?  I'd think mfrs would make some of
the stuff with exterior glues?  And is there an equivalent to the smoother
grades of plywood also, for other uses?

                         -|//*Alan Courtright*\\|=
                                Poulsbo, WA
                             acourtri@krl.org




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______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
Solstice http://www.crest.org, and BuildingGreen, Inc., publisher of
Environmental Building News and GreenSpec http://www.BuildingGreen.com
______________________________________________________________________