Determining the species of Wood Beam 3

[waytsh]

I am trying to determine the species of several timber beams reclaimed from an old barn. Of course I am trying to determine the structural properties, but beyond that I am just plain curious since some of the scrap may be used for furniture. Does anyone know where I can send samples to have them tested and also how much this sort of testing might run?

thanks,

~waytsh

 

[jimzpe]

Try a college or university close to you. I take my samples to a professor in the technology school at our local university and he identifies them for me (I can't pay him due to school rules but donate to the program as a substitute).

 

[jike]

The Forest Products Lab (Center for Wood Anatomy Research) in Madison, Wisconsin will identify up to five samples per year as a free service to US citizens.

See

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

for more info.

Good Luck!

 

[waytsh]

Thank you both very much! Good information.

 

[rholder98]

Short of having samples tested, is there a way to check (or assume) the capacity of existing wood members? I had a project once where we were converting a 40+ year old building from retail to restaurant use, and I had to check the existing joists, both first floor and roof. They were 2 1/2 inches wide x 11 inches deep (actual dimensions), so they weren't a standard size, or not one that I was familiar with. My supervisor told me to assume SPF #2 for the species. Anyone else have similar experiences? What's the best way to go?

 

[boo1]

For identification of wood species, an additional identification recommendation is Wood Advisory Services (see <

http://www.woodadvisory.com/>),

contact Al DeBonis. Although they are located in Millbrook, NY, the sample can be shipped.

For wood strength ASTM D143, D245, D1990, 2555, and D4761 are the appliable testing standards in the US.

ASTM D143 is one of two basic mechanical testing Standards for wood in North America when the goal is to develop estimates of properties for structural design. ASTM D143 tests small clear (knot- and defect-free) specimens then modifies the clearwood properties and their variability to estimate the 5th percentile of clearwood property then further account for the effects of knots, slope-of-grain, density, and grain orientation (flat-, quarter-, or bastard-sawn). With flat-sawn lumber the growth rings are parallel to widest face. With quarter-sawn lumber the growth rings are perpendicular to widest face. With bastard-sawn material there is NO control on growth ring orientation. Bastard sawn most accurately reflects actual production lumber. ASTM D245 instructs the user how to use D143 values to derive allowable design stress (ADS) values. ASTM D4761 is used when testing production-sized lumber and timber. ASTM D1990 instructs the user how to use D4761 values to derive ADS values. Both methods are used to derive allowable design stress values in North America. Most hardwoods use the D143/D245 methods, most softwoods use the D4761/D1990 method. The former was used from 1934-1990, while the latter is now the preferred way.

Consider a 3-point flexural test method.
see the proceedures listed at:

http://www.fpl.fs.fed.us/documnts/pdf1997/green97a.pdf

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm

see ch6
and additional info at

http://www.wwpa.org/_techguide/subscribe.asp

see TN4 and TN5

Cheers
Boo1

 

[samdamon]

Great post by boo1. Would add that the Forest Products lab can identify the species but not the grade of timber that you are dealing with. You will probably need to conservatively guesstimate the timber grade in order to pick out allowable stresses from published NDS tables or old design sources. If you want to learn and use modern grading rules believe they are published on the web for the different species. I personally have not tried to learn these rules, visual grading takes a little while to learn and also probably takes some practice to get good at. Depending on what you are designing or checking, it may be simpler to make an educated but conservative guess about the grade.

Note also that published allowable stresses for some species have changed over the years, because testing methods have evolved, and also (I've been told) because recently grown versions of some species simply don't have the strength their old-growth incarnations had. (Why that is might be another good topic for this forum.) When looking at a very old wood structure it may be advisable to at least start with a review of any design data that you can find for your wood species that is contemporary with the building. Hope this helps. Good luck.