shed load bearing wall and floor joist layout question

[kansascats]

Posted over in rec.woodworking, just pasting URL here. Could use your help please.

[kansascats]

Posted over in rec.woodworking, just pasting URL here. Could use your help please.

[rlz]

I didn't read the entire thread, but from what I read, I would put the load bearing walls so they sit completely on a floor joist, not perpendicular. That way you have the weight evenly distribute across your skids. If you do it the other way, most of your wall\roff weight is only on two skids.

Rob

[John]

I read a good bit of what you wrote and disagree with the 2x4 joists, too flimsy to walk on. If you insist on joists use 2x6's on 16" centers and at *least* 3/4" thick flooring material, a doubled layer of 1/2" treated ply would be even better. Anything near or touching the ground should be treated anyway.

The more common way is to don't use joists at all and screw the treated flooring directly to the treated 4x4 skids sitting on a well tamped gravel base.

But if you insist on joists I would double up the joists on the sides (what you are calling load bearing) and place them across the 4x4 skids. That way if a 4x4 rots out (likely) then the side won't collapse, the floor will just get mushy and warn you that you should have ...

Poured a concrete pad and anchored all four wall sole plates to it. No worries about rotted wood or insufficient structure underneath. Use the

4x4's that you apparently already have on hand as corner posts in standard 2"x4", 16" o.c. wall construction. Use doubled treated sole plates for the walls, stronger and bugs aren't too fond of the taste.

Considering that the latter construction will probably last longer than you or me the extra money really is worth the investment. To tell the truth I built one on a 4" reinforced concrete pad at a previously owned house (also 8 x 12, but regular 1/3 roof) in the early 80's and the people living there now are still using it. 30 years and it still looks as good and sturdy as when it was built.

John

[kansascats]

John,

Interesting post. I've been going with the ideas I've seen around here. Basically portable sheds, albeit at 8x12 or 10x16, "portable" becomes an interesting feat.

This "shed" however is likely to need to be moved in the future. I will lift the skids off the ground by 3" to 9" on concrete blocks, etc to get even the PT 4x4s a bit more "room". My joists are PT as well. Planning to use 4 skids along the 12' (long) side. So 1' in, skid,

3', skid, 3', skid, 3' skid, remaining 1'. Atop those, and perpendicular, 7 12' joists capped on the ends with an 8' 2x4. 3/4" t/ g osb-ish flooring (primed and painted on the top side (maybe bottom and edges as well), then the load bearing wall --- the 12' long one -- will sit atop the 12' outside joists. I'll frame up about a 6' high wall and then a gambrel roof atop those -- again with the load bearing side being the 12' long wall.

[aemeijers]

So you have an industrial forklift or crane to move it with, when the time comes? :^) That sucker sounds heavy. Traditionally, the skids go the long dimension, and the joists (if any)the other way. Unless shed will be moved sideways, it makes the skids resist rolling better, and provides a full-length tie to the structure so you don't tear the end off if you are dragging it or something. As to wanting the long wall atop a joist, if your wall has a bottom plate, that really isn't needed. The box section of the joists and rim joists and floor decking above, is plenty strong enough to support it. I would up the joists to 2x6 16"OC, in case you want to put anything heavy in there. I'd also use the appropriate iron-mongery (probably available in the deck aisle) to tie the joists to the skids. Most of your cost is the labor, which in your case is just your time. The additional material cost to overbuild the floor system is minor.

Not a fan of any OSB product for flooring, especially in damp environments, and where there is not a wear layer over the top. Seen too many get funky-smelling or splintery in short order. Marine plywood, if such a material is still available, is what we used back in stone age for cabin floors. It was even available with a factory finish one side, ready to walk on. If OSB is what is available, I'd definitely seal all six sides (pre-installation) with something weather-rated, and look for some kind of non-moisture-retaining traffic mat material, at least for near the door.