Reclaimed Timbers

[Eldorado]

I have a client that wants to use reclaimed timbers as structural elements for a project (rustic exposed timber trusses). I told him that, in addition to visual classification of the components, I would need to have some testing done to verify the material. The project is relatively small and I stressed that it would be less costly to use new timber material that is already classified. He may want to go with the reclaimed timbers anyway. I am getting more and more requests for reclaimed timber use, so I would be interested in any experiences the community has had with them. Thanks in advance for any comments you can provide.

 

[MiketheEngineer]

See if you can identify the wood and then use the lower grade values.

I have done this a few times and when I don't/can't figure out what I have - I just usaully use an Fb in the 750 to 1000 psi range.

BTW - do the analysis - you might only need say 500 psi and just about any timber/lumber will give you that!!

 

[msquared48]

I agree with Mike here.

Some jurisdictions, though, may require two stress grades below what the material appears to be. Check with your local jurisdiction.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Eldorado]

Makes sense gentlemen. Since the timbers are reclaimed I won't really be sizing the members much, the size will already be established. I like using low design values and either it works or it doesn't. Yes Mike, I will do the analysis and see where the "chips fall".

Thanks to all for your input.

 

[a7x1984]

In a situation like this, I use the recommendations from here:

http://www.apti.org/clientuploads/pdf/Anthony-Dugan-40-2.pdf

They developed a database to correlate the grain angle and the knot sizes to the grade. And like our buddies mentioned above, you choose the lowest capacity species. Visually grading wood is easy to do, so there is no reason to be overly conservative with it (unless you suspect dry rot, termite damage, etc). The species, on the other hand...good luck.

If I got paid for every hour I worked, I'd be a wealthy man.

 

[Eldorado]

Thanks for the article a7x1984

 

[IsaacStructural]

This comes up often when looking at existing structures. Often you've got some joists in place and you can't really get any information on the existing material, and testing is cost prohibitive. Like MiketheEngineer, I've typically calculated the actual stress and seen just how low of a strength material would satisfy.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[abusementpark]

What do you guys use for a wet service factor (CM) for reclaimed lumber?

 

[abusementpark]

Also, any recommended general notes for preventing them from using reclaimed timbers that are in poor condition?

 

[a7x1984]

abusementpark: AWC has some links - AWC Link

Also:
1. Contact the US Green Building Council - that will definitely have a spec on that (it may cost you)
2. Have you tried the Masterspec, Division 6?

In Russia building design you!