Replies

1. 
   MarkH | Aug 08, 2014 06:00pm | #1

   I would use 2 4x4 6' apart or even 7'+.  PT should last a long time if they are kept dry.  So, the pads must be well above grade and stable, not just placed on the ground.  Here in Ohio, about anything in my area will sink into clay, and move all over the place in winter if it is just setting on the earth.   A somewhat easy way to support the skids is to dig a trench to approximately frost line and fill it with gravel.  Easy in the south, not so much in the north.

   6x6 or 8x8 skids might be a better choice if you intend to drag the shed to another location.  Bevel them so they skid along the ground easier.

   Nails vs screws; really, nails can be harder to pull out because screws are brittle and are more likely to break instead of pulling out.  So, that's your choice, one is not necessarily better than the other.

1. 
   jt303 | Aug 09, 2014 10:15am | #2

   at least 6' apart.

   Thanks Mark, seems foolish in hindsight to have them closer, the floor with skids under at 4' apart is unstable.

   pads - gave me something to consider,  will have gravel under them, in temporary location thinking to put a couple of inches, not sure amount of gravel in final location. Plan to lay a stone patio next year so will have gravel delivered. Was under the impression that 4-6 inches was sufficient, although mostly clay soil here in the area (Ottawa, Ontario). Really not sure. Frost line is around 4'  in the Ottawa area.

   Thanks for insight on screws, was considering putting a couple of 7" lag screws from the inside of the shed, through the wall base plate down to the skids, so that they are out of the way and I could easily remove them, but just more brainstorming than a practical idea.

2. 
   renosteinke | Aug 10, 2014 09:40am | #3

   There's no substitute for having a properly designed floor & foundation. Here are some thoughts:

   1) I have a set of plans I bought for building an 8' x 12' hunting cabin. The designer has the building supported on a pair of skids. The skids are actually 'boxes' made from 2x6's (sides) and 2x12's (top & bottom). His idea was to allow the cabin to be towed, or re-positioned, about the site. Two wide skids, lengthwise, each set perhaps a foot back from the perimeter, and each extending at least two foot beyond the ends of the cabin. 

   2) My neighbor had some "constrction experienced" friends build his shed ... and his floor has collapsed at least three times. Guess their creative framing wasn't so smart after all!

   3) My shed has a rock-solid floor, after a decade of heavy use. It may be a 'small' shed, but it is severely loaded. How loaded? Well, for the past five years it has been packed with cases of bottled soda. Yup - when I moved, I moved the shed to a local mini-mart, where it's used to store excess inventory.

   So, how did I make my floor?

   Well, the first step was to get the floor, and framing, off the ground. I used concrete pier blocks; if your ground is level, you can easily use ordinary bricks or patio stones. This leaves plenty of space for drainage and ventilation - and the framing is never sitting in water. Given the right ground, you might also be able to accomplishe this with a bed of gravel.

   Next, I made a proper floor frame. I've lost count of the sheds I've seen with failing floors, where the 'floor' was simply a sheet of plywood laid on levelled ground! No- you need a frame! For my floor (which measured 4x8', I used 2x6's around the perimeter, with 2x4 joists every 16", assembled with steel joist hangers. Floor decking was 1-1/8 T&G subfloor, glued & screwed, with sheet vinyl glued atop it.

   Is 3/4 subflooring strong enough? Probably - it all depends on your use. 

   Your floor is more than twice as large. I'd frame such a floor with three lengthwise 2x6's, and extend the 2x4 joists to a 5' span, on 16" centers. Since my shed had three pier blocks along the 8' dimension, I'd repeat that .. for a total of nine blocks under the frame.

   What if ... I wanted a shed with a floor level with the ground - say, I had to roll carts and drive the lawn mower out the door? Well .... sure, you can build a ramp ... but part of me thinks that you could also put the blocks and floor frame into a hole in the ground, bringing the shed down to ground level. The key here is to have excellent drainage, and a steel grating to make a 'driveway' into the shed. Were I to do that .... hmm... I think I'd also face any wood that was in direct earth contact with something like vinyl flooring or shower pan liner, or even galvanized (not aluminum) roof flashing.

   If your area has termites, you want to raise the shed. Period.

   Finally ... 

   4) How would I make a shed 'portable?

   Well, my shed was sized to fit on a trailer. Of course, your shed is larger ... and you plan to move it only a few times, across your own property.

   Why not .... simply cover the undersides of the framing at the "rear" end with 1-1/2" steel bar stock? Run a loop of steel cable through the framing st the ends (and under the joists) with a generous extra length on the 'tow' end? You ought to be able to catch the cable with your hitch and ... pull! 

1. 
   jt303 | Aug 10, 2014 10:49am | #4

   Thanks for the info. That would make a strong 2x6 frame, expect will stick with 4x4 though. Luckily termites not so common here. Like the idea of being able to roll in ground level, but no tractor, just mower and tiller so ramp will probably have to do.  No vehicle acces to tow unfortunately, unless I rent a skid steer to help with the stone patio work.  Again new territory and more questions. But I'm drifting. :) Might add bar later. Cheers.