(06-12-2018, 08:49 PM)jteneyck Wrote: Well, yeah, not the most fun job but I wanted a stable base that won't shift over time.  I think my friend had the hardest job digging that trench.  He cut a lot of tree roots along the way.  We were smart enough to take a day off to recover before finishing the hole.  And the tractor was huge in getting the stone up to the hole.  

I forgot to mention it in my post, or take a picture of it, but there is what must be the world's best geotextile under the stone.  My neighbor gave me a piece of polyester paper machine drier felt that he got from a local corrugated manufacturer.  It was a perfect 17' wide and about 25' long.  We laid it in the hole after the drainage system was installed and then dumped the stone on top.  I cut off the excess before I took the "after" photos, so you would have to look very closely to see it.  He put over a thousand feet of it under the road he built at his gentleman's farm.  

Jim, thanks for the advise on the flooring.  I am definitely going to go with T&G material for the floor, and I will paint the bottom as you recommended.  The joists are 2 x 8's, 16" OC and the span is only 4.5' between the 4 x 4's.  The span rating at L/360 deflecton is around 7.5 ft at 120 psf total live and dead load, and 1 ft more at 12" OC.  I couldn't find span ratings for higher loadings, but clearly this is going to be very robust.   I was going to use 2 x 6's, but found out they can't get PT 18 feet long (for the rim joists), only 20 ft long 2 x 8's.  So I upsized all the joist stock to 2 x 8's, rather than ripping down the 2 x 8 rim joists to 6".  

John

(06-13-2018, 08:36 AM)jlanciani Wrote: My reasoning for the 12" centers for the floor joists isn't for the joist sag, but for the ply or Advantech. I have two sheds that I built on my property, one with 16" spacing and one with 12". The 16" spacing has very noticeable sag and bounce in the 3/4" PT ply. Both use 2x10 joists and have 12' span.

(06-13-2018, 12:14 PM)jteneyck Wrote: I found a source of 1" AD larch about 40 miles away and think I'm going to go with that.  Hard and rot resistant.  At $1/BF it will be no more expensive than PT plywood and I'll be able to stick with 16" joist spacing.  

John

(06-13-2018, 01:05 PM)CLETUS Wrote: What about treated T&G 2x skirt boards for the flooring?

(06-13-2018, 02:18 PM)jteneyck Wrote: Didn't know there was such a beast until you posted it but, yeah, that would work.  I'll bet it's a lot more than $1/BF though. I may do a tongue and groove, or more likely a shiplap or spline with the larch, if anything.  I'm not hung up on the floor being perfectly flat, smooth, or crack free; as long as the boards fit together reasonably tight I'll be happy.  

John

(06-13-2018, 02:26 PM)CLETUS Wrote: Not sure how the cost would work out, but it would give you a 1.5" thick treated floor. I'd prefer that over 3/4" ply for your application.... I think...

(06-14-2018, 09:02 AM)daddo Wrote: Any considerations for high winds/tornadoes that may want to lift the building?  I know direct hits are a loss, but close calls can be very destructive as well.
Maybe you don't have to worry about that where you're at.