advice on selecting a grade for old lumber 1

[MikeE55]

Does anyone have advice on selecting a grade for old lumber that was sawmilled before the current grading system? I am looking at engineering a renovation of a 100 year old building, constructed with lumber which is obviously a better grade than #2 SYP. Are there experts who can evaluate the lumber? Or is it up to the structural engineer to assign a lumber grade by making an educated guess?

 

[RWW0002]

There are some field grading guidelines that can be used for field grading lumber (See attached from the US Parks Dept.), but I doubt you are going to be able to grade field grade in place lumber and arrive at better than #2 for a whole floor system. You are very likely to reach No.1 for specific members, but it would be a very time consuming process to grade a whole floor system (and a good chance that there would be random pieces with knots too close to the tension face or a grain slope issue).

Historic structures are sometimes assigned higher design values than current codes based on in place grade and the historic strength of old-growth forests versus the relatively young trees harvested today. If you are trying to justify a strength close to today's #1 So. Pine you may have a good chance of reaching it, but you may have to grab some historic codes (think historic codes or engineering handbooks from around the time of construction - Carnegie Pocket Companion or similar), along with your field grading data to reach it.

 

[RWW0002]

Another useful resource is the US Dept. of Agriculture Wood Identification services.

https://www.fpl.fs.fed.us/research/centers/woodanatomy/wood_idfactsheet.php

It looks like they no longer id samples from businesses, but I have used them in the past to confirm a species for an owner. There are similar services that will do this for a small fee.[ignore][/ignore]

 

[RWW0002]

One more link, I forgot about this one. Great resource for species ID and geared specifically towards design value determination.

https://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr228.pdf

 

[MikeE55]

Thank you RWW0002! The links were useful.