Hello all, this is my first post here on the forums. I have a timber frame (TF) workshop designed (for working timbers in inclement weather). I have a question on loading for floor systems. And possibly suggestions on sizing/spacing on floor joists.

First, my TF is 16'8" x 24'8" (including size of the 8x8 sill plates). Made of Eastern Hemlock. I am considering 4x6 floor joists.

My question is: what should be considered for dead and live loads on a flooring system? I am a civil engineering grad student, and know about the loading values stated in code books. But for a small workshop TF, I cannot find much reliable info. And I have no experience in analyzing timber structures.

I have seen as high as 12 psf for dead loads and 40 psf for live loads for a flooring system. I highly doubt that my structure will see values as high as those. The live load will consist of:
1.) Maximum of three people (600 lbs)
2.) Maximum of two timbers at a time, with sawhorses (600-700 lbs)
3.) Two or three workbenches - unsure of weight
4.) Wood stove
5.) Tools (mostly hand, very limited power tools - and none larger than circular saws or chain mortiser)
6.) Tool storage

With a very conservative estimate of 2500 lbs total live load, across a 16x24 (384 sq. ft.), I am looking at 6.5 psf live load. With a deflection limit L/360, that would be about .39".

And for the dead load, I assume that only the floor joists and floor boards would actually contribute, since the sill plates are resting on concrete piers. Would the sill plates come into the value of dead load? And would 1" flooring be adequate, or should a sub-floor also be used?

So I have seen in one of Sobon's books, 5x7 joists with max spacing of 2' 6". Assuming he is using the code standards of Dead=12 psf and Live = 40 psf.

Can 4x6 joists be spaced maximum of 2' 9" O.C. while spanning nearly 12', in my case described above? Or does this sound bad? Spacing varies in my design (non-uniform), with min=2' 8" and max=2' 9". I would need dead load to get load combos in LRFD, to get my actual deflection.

The joists are tapered to 4" to avoid shear failure. And the center joist in each bay is dovetailed.

Any suggestion for alternate joist sizing/spacing/span would be appreciated.

Thanks a bunch if you followed me all the way through this post. I, along with my brother (who is also an engineer and worked as a timber framer for a year), are hoping to get more involved with TF and help bring this great style of building back into the mainstream. I appreciate your help and look forward to getting to know people on here.