Questionable floor joists

[M3TG]

I'm finishing off the third floor of an 1890's victorian home, and was wondering about the load capaities of the floor joists. I have done alot of research already, and according to current building codes, the current floor is not suitable for a living space. The only factor I can't account for is the wood type used for the joists. Does anyone know where to find the load ratings for lumber other than pine?
The current floor's specs are: 2X6 (true dimensions) WALNUT joists that are spaced 16" O.C. across a span of 14'.
The 3rd floor was used as servants quaters back when the house was built, and it seems structurally sound, but I want to build a master bedroom suite with a full bathroom and wanted to know if the floor would support a standard whirlpool tub without sistering all the joists.
Thanks for any info!
Todd

[Snoonyb]

I would think that a historical restoration society be your first choice of inquiry.

[fredmorrison]

I am converting and attic to living space and it has 2x6 floor joists and 12 foot span. This is not adequate for stress or deflection. A structural engineering solution is to make a T-section using another 2x6 8 feet long centered and laid flat on top of the existing joists. This way I dont have to be concerned with existing wiring through the joists as I would with sistering along side the existing joists. The nailing specification requires nails on 2" centers for 2 feet each end and 6" centers for the center portion.

14 foot span would require some calculations to see if such a solution would work for you.

[grover]

Here's a idea: sell the walnut to a local woodworker, and fund the whole project! Maybe even make you some nice furniture out of your house :D Man, I can't believe it used to be so cheap they'd stick houses with it...

Here is a table with the mechanical properties of various woods:
http://woodworkweb.com/woodwork/contentid-17.html

This site lists E for Walnut is 1.68x10^6, compared to 1.98x10^6 for most of the southern pines; (I assume this is all for top-grade "woodworker" wood on that site?). Typical knotty #2 has an E of about 1.60x10^6. The standard span tables are probably not too far from the truth for your joists. I certainly wouldn't put a whirlpool on it, that's for sure!