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RE: mold growth on joists

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I encountered conditions similar to yours a some years ago when inspecting
an abandoned restaurant which had been partially open to the weather for a
few years.  I recommended removing all of the affected trusses during
renovation.

The "Wood Handbook" indicates that decay (as the result of molds and fungus)
first affects toughness, or the wood's ability to withstand impacts,
followed by reductions in properties related to static bending and then
ultimately all strength properties.  From laboratory tests, it was shown
that by the time a 1% weight loss of wood due to decay occurred, toughness
losses from 6% to >50% occurred (this depends on both the fungus and the
type of wood).  When the weight loss approaches 10%, most strength losses
may be expected to exceed 50%. At these weight losses decay is only
detectable microscopically.  It can generally be assumed that wood with
visually discernable decay has greatly reduced strength properties.

For these reasons and those mentioned by Lawrence Boyles, I would remove and
replace the affected joists.

Albert J. Meyer, Jr., P.E.
Martin Engineering
238 North 22nd Street
Philadelphia PA 19103-1004
(215) 665-8570
(215) 561-5064 Fax


-----Original Message-----
From: Peieng5590(--nospam--at)aol.com [mailto:Peieng5590(--nospam--at)aol.com]
Sent: Friday, March 15, 2002 7:40 AM
To: seaint(--nospam--at)seaint.org
Subject: mold growth on joists


Any words of wisdom as to the damaged caused by the growth of mold on wood
joists, and by mold I mean mushrooms and hairy looking stuff and filmy
looking stuff.  Some joists have obvious degradation noted by shoving a awl
in and through the joists, the problem is: after the moisture  and
ventilation is fixed, what do we do with the joists that are still hard,
seemily undamaged, can we leave the stuff adhered to the side of the joists?

Jeff Fertich, P.E.
Gettysburg PA

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