Early 1800's Ohio Timber Species/Timber Cracks 1

[brewdizz]

I am analyzing timber roof trusses, investigating the potential of turning current attic space into office space. The building was built in the early 1800's in Urbana, Ohio. Where might I be able to find information about the species of the wood?

Also, some of the larger members have shrinkage checks along their centerlines. NDS does not have any factor to adjust for this, it is typically accounted for in the grading rules for new construction. Since I do not know the grade or species of the wood, how can I incorporate these defects into my allowable stress values? Could they lower any stress values besides Fv, shear stress?

 

[dik]

Checking of large timbers used for trusses is not uncommon and because the elements are generally loaded in tension or compression, checking generally has little effect. Failure of trusses is generally initiated at the joint and joints should be carefully reviewed. Species can be determined by someone specializing in wood... you might check with a local university. Grade is likely comparible to select... early timber was usually cut from mature trees with closer spaced annual rings and fewer defects... again a local timber specialist can be invaluable.

Dik

 

[SlideRuleEra]

The USDA Forest Products Lab offers a wood identification program. Here is a link to get started

http://www2.fpl.fs.fed.us/WoodID/woodid.html

As for evaluation of the existing members, the Forest Products Lab has done a fair amount of research on recycled lumber. Their general guidance is to downgrade the "used" lumber one grade from what it would have been consider when "new". I understand that you are not really recycling the lumber, just using it "as-is" for a new application. Still, the one-grade reduction sounds like reasonable advice. Here are a few FPL documents (free .pdf downloads)so you can decide for yourself:

"Effect of Damage on the Grade Yield of Recycled Lumber"

http://www.fpl.fs.fed.us/documnts/pdf1999/falk99c.pdf

"Stress Grading of Recycled Lumber and Timber"

http://www.fpl.fs.fed.us/documnts/pdf1999/falk99d.pdf

"Evaluation of Lumber Recycled From an Industrial Military Building"

http://www.fpl.fs.fed.us/documnts/pdf1999/falk99a.pdf

"Evaluation of Recycled Timber Members"

http://www.fpl.fs.fed.us/documnts/pdf1999/ramme99c.pdf

This Naval Facilities Engineering Command document may also be helpful:

"Inspection of Wood Beams & Trusses"

http://www.wbdg.org/ccb/NAVFAC/OPER/mo111_1.pdf

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