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Re: OSB roof and shearwalls wet from these rain

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Once the board has swollen there's not much to be done.  ALWAYS warn
Contractors of the danger of using OSB in, especially, exposed locations,
even with so-called exterior grade!!.  It pays to recommend plywood in
exposed areas with the proviso that if the contractor wishes to use OSB (is
it cheaper in the USA?) that he requests use of the same and then you can
provide written instruction that it be protected at all times and that its
maintenance is the responsibility of the contractor.

  My own slip-up, some years ago now, was avoided because there was little
rain during construction, however, it was 2 weeks before they covered the
board and the action of sun, wind etc was beginning to tell!!

You may end up having to strip and re-sheath if there is severe swelling.
If it has not yet reacted seriously to the moisture you MAY be able to apply
a "sealant/wood restorer" but I doubt any resurrection once the fibres have
de-laminated and broken from the resin matrix.

Get good materials/expert help because you may also have a fight with the
contractor who will no doubt blame you for the specification.

Thor Tandy  P.Eng
Victoria  BC

-----Original Message-----
From: EDLStruct(--nospam--at) <EDLStruct(--nospam--at)>
To: seaoc(--nospam--at) <seaoc(--nospam--at)>
Date: Monday, February 09, 1998 1:12 PM
Subject: OSB roof and shearwalls wet from these rain

>Dear fellow engineers,
>I designed this commercial building using OSB boards for both roof
>and shearwalls.  Now is being contructed.   They are not covered when these
>heavy rains hit.   I am afraid that they might swell and lose strength.  If
>anyone who have experience in using OSB which got heavy rained on and would
>like to share your experiance with us about this matter, I would appreciate
>Ed Latthitham S.E.
>Oxnard, CA