Hi Brent,
Well sounds exciting!!
First, before even writing one sentence, I have made it a habit when "assisting and suggesting" possible timber framing scenarios that involve clear needs of PE expertise...to suggest just that...GET A PE with timber framing background...
Sorry, that is just a disclaimer that I have be well advised to give, in as such that if one has to ask the questions..."is this big enough"...then they either need a PE and/or can't properly do the engineering, timber, and joinery assessment themselves.
Please know I am very excited for you and wish you all the best, yet our share "opinions" are just that..."opinions" and not the replacement of good knowledge and experience and/or the help of a PE...
Completely understood! To be fair, no aspects of the math intimidate me, I'm just partly being lazy and partly uncertain about the different loading scenarios because I haven't had time to read up on them yet and time is getting short! Good to see confirmation my understanding of the concepts and principles are sound though!
With that stated...here is my two cents:
As a facilitator of traditional historical and natural builds...concrete of any kind is the last thing I like seeing on a job (unless a natural concrete of some form is applicable for a historical restoration) so I am pleased you are going with a raised floor and a stem wall.
So a few more details. We are doing a rubble trench scenario with short stem wall, but also stem walls running across the building under the bents upon which another 8x8 "sill" will sit. Since the bents are 12' spacing and the building is 24' wide, the interior space that is to be filled with the raised wooden floor is 24x12'. So joists going across the gap the shortest way are 12' long and will join with 8x8s that sit on concrete. Maybe you figured that out, but I just wanted to make sure!
From what I have gleaned thus far, you need the floor of an old Mill or Barn...not a garage or house. Having restored, blueprinted and seen thousands of such structures over the decades, I think a 6x6 is barely the minimum...
I would also suggest that a "fully housed dovetail" is going to be the only form of this joint I would even possibly consider as any other "dovetail" shall be inadequate and present with possible shearing issues especially over time and in White Pine.
Absolutely. This is why I'd planned on a fully housed dovetail.
So with that said, your loads are going to be "transient point loads" of "high weight amounts"...very similar to a barn, mill, and/or industrial garage or other such structure.
Excellent to see the terminology, thank you.
The planking on top should be a minimum of 50mm to 80mm splined or T&G and/or toggled at 300mm intervals. Plywood can be part of this floor diaphragm matrix, but is neither necessary nor traditional.
If staying with 150mm x 150mm (~6"x6") then my rough math suggest a spacing of 400mm to 500mm minimum for the potential loads this floor could (and probably will be) subjected to.
Wondering about the legendary strength of my full 1" T&G white oak though and how much ply material would be required in concert with this? Would love to have plank underlay, but didn't have time to saw the material.
The Joist could also just rest on top of the sills with added height to the posts to compensate for elevation gain.
Spacing could go to 600mm and maybe a bit further if a thicker plank floor matrix is employed.
Many (most?) traditional structures of this nature (i.e. barns, and older mills) only used log bolt sections as joists, hewed on two side laid on the flat...no joint often...resting on sills...Their average spacing is 400mm to 600mm with most being 175mm to 250mm thick with a 50mm plank floor on top...This is just a mean average range I have observed...
Good Luck and post pictures as you progress...
Thanks for sharing the project,
j
Alternatively, what if I made a slightly wider stem wall such that wider and deeper joists could rest on the concrete itself with no housing in the sills. Could even consider 8x8 joists with dovetails cut in the ends to tie everything together but a housing would be exchanged for a good bearing surface on the wider concrete. I could cut some more joists, and save the 6x6 for other projects. I'm cutting it tight already for height on on the first floor, and already have the posts cut so I can't really put joists on top of the sills.
Thanks very much for your helpful post Jay, appreciate it!
B
p.s. This building is based heavily on the 24x24 high posted cape in Steve Chappell's book.
