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Re: Historic Wood Structures, DECAY

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I scanned most of the replies regarding the 85-year-old oak framing that was
left exposed to the elements for three or four years, but found little
specific reference to what would be my biggest concern:   Decay.

A recent (last 24 months?) article in the ICBO "Building Standards" magazine
outlined the "pick test" for wood.  It used Douglas Fir as an example, may
not completely apply to oak.  To perform this simple test, you will need an
awl or other pointy object.  Poke the awl into the area of wood you want to
test, about 1/8 inch deep, and then pry up some of the wood fibers.  If you
hear a pronounced splintering sound and pry up some long strands (one or two
inches long) of wood fibers there is probably not enough decay to worry
about.   If your awl just pops out some short chunks of wood less than 1/2
inch long, and/or if the pried-up wood breaks right over the awl, you have
decay.

THE  SCARY  PART  is how much strength the wood has lost if your test
indicates decay.   Something like 70 percent of the wood's "resilience" (I'm
pretty sure that that was the term they used--would have been much more
helpful to say "bending strength",  "stiffness", etc.) can be lost by the
time you can detect decay with this test!   The article recommended
replacing certain members (such as balcony supports) if the pick test
indicated any decay at all. Another article I read long ago stated that up
to half of the wood's strength can be lost at the point when a trained
specialist can just begin to detect decay under a microscope....



Good luck!

Thor

www.shearwalls.com





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