15 Nov 05 23:38
I was out of town and just read this post - I'd have to second what UcfSE says - there is a lot more to this than using some applicable equations and assuming some wood properties of old lumber.
In fact, Bob, I would suggest that you are putting yourself in serious difficulty should the floor get loaded beyond its capacity and fail. Here's some thoughts:
1. Your purchase of the existing building and the use of it is most likely putting you under the local building codes and your use of the floor for storage, etc. would be dependent upon a proper evaluation of the floor loading capacity.
2. If you aren't licensed in structural engineering in your locale, then you are adding to your liability by performing engineering calculations to determine if the floor is safe for a particular load. This could be construed as practicing engineering without a license (assuming you don't have a license - forgive me if you do).
3. Even if you have a license, it sounds like you aren't well versed in the structural field, so this again may be violating the engineering laws in your area. (your handle says "mechanical").
4. Should something fall down and injure someone, you would be held liable for the damages.
5. Many insurance carriers require mezzanine and other floors to be load rated to qualify for insurance. I've checked a number of mezzanines just for this purpose.
So all of my wordiness above - to simply suggest that you go out and hire a structural engineeer to evaluate the whole structural system, not just the floor.