Shed building questions

[siliconbauhaus]

Maybe too late but here's my 2 cents, this all depends on what your deck is made of and that it will take the load. You can do the framing one of two ways. You can frame it so you build up to the underside of the rafters or you can do it in two pieces and set your walls out the be all the same height and then add the framing for the roof part.

As you have a deck that's reasonably level use it to do your framing on. Set out your PT 2x6's for you floor and makes sure its square by checking the diagonals. Everything will be set out from this so it needs to be right to start with. You can now shim it with some PT scraps if necessary.

Once you have your outer rim joist together and square, cut your 2x6's for your inner joists and set them out at 16" centres. You can either attach with hangers or fire 3" deck screws into the ends. When this is all done you can set down your floor sheets. They can be osb or ply but I'd use 3/4 ply personally. Attach your sheets so that they are perpendicular to the joists and screw them down. When all screwed down you can then snap chalk lines to follow with a saw to cut the flooring overhang.

Use the new floor deck to do your wall framing on. Set a 2x4 for the base plate and mark out your 2x4 stud positions @ 16" centres (or make a spacer). Assuming you want a top plate height of 8' your studs should be 7'7 1/2" long ( 8' - bottom plate and top plate x2) As you are framing something small you can actually screw up through the bottom plate into the studs rather than toe nailing them and do the same for the first top plate.

Where you have a window you need to work out the rough opening size for it so take the frame dimension and add 1/2" to all side. This is the dimension you frame to. You normally double the studs where the rough opening is so that your sill plate is sitting on a cripple stud either side (cripple stud is a partial height stud). I would agree that twin 2x4's with a ply infil is sufficient for your header but I'd do it as a 2x6 as it's the norm. The same concept applies to your door head although you would definitely want 2x6's for a 5' span.

Once you have your framing done, set one side up and brace it for plumb. Bring the next side up and do the same.When the 2 pieces are all kosher plumb wise you can then add the second top plate so that it overlap one frame from the other. Repeat again for the other two sides.

A mono pitch roof is certainly faster and easier to do but it's up to you. If you chose the frame it all at one level option now is the time to frame up the infil for the roof part. You want to use ply or osb for the sheathing and leave a 1/8 gap between the abutting sheet to allow for movement. Lay down from the bottom to the top strips of 30lb roofing felt and staple it. Next comes your shingles and you'll need 2 packs of them and preferably with the white finish along with some strips of drip edge. Your drip edge goes under your felt at the bottom edge but over the felt on the sloping sides. Take your shingles and cut off the tabs of a few to lay down as your first row from the bottom. Then place a row of full shingles over these and then carrry on up the roof.

For the siding you can use anything you like. Cement board is a good low maintenance option.

If you have any other questions and I haven't sent you to sleep feel free to ask.

[Tom Miller]

7. Lastly, on the floor: The deck is not as flat as I thought it would be, although it's pretty level. Should I build a floor frame out of 2x4 that the treated plywood can sit on, or should I use 2x6? The shed will cantilever by about a foot over the deck on one side. Also, what shims do I use for the floor? Will the regular cedar shims be okay? Are there special stuff I should know about?

Or do I rent a drum sander and sand the thing flat?

Is it just the decking material that's making it not flat? If the joists underneath are not the problem, how about just removing the decking in the area that the shed will sit?

Otherwise, if it's just that the decking is a little warped, it might not look flat when you lay a joist across it, but when the floor is fully loaded, it might flatten out. Then, any shimming you've done is now a problem.

Regards,
Tom

[Anna]

Hi, everyone. Thanks for all the great advice. Trying to digest them now.

The floor:

The decking is 2x6 Douglas Fir. It's 10 feet wide on the far end near the fence and about 24" off the ground at most (the ground slopes in two directions). I thought about not putting down the decking where the shed is going to sit, but my husband suggested to just do it anyway (and yes, he does get the blame for everything).

The joists are 2x6 spaced 16" O.C. Where the shed will sit, the beams are 3 feet apart — because at that point the shed was supposed to be 10' by 4'. Currently, there's a 2x6 ledger attached to 4x4 fence posts, then a 4x6 beam about a foot out, then another beam 3 feet out.

I'm not sure why the floor is not flat. I think it's the way I installed some of the joist hangers. I didn't think about using a scrap 2x6 until too late, so a couple of the joists were "bulging" over the beam. I guess I can take some of the boards out again and re-do it, although I'm pretty reluctant to do that right now because I just finished the stupid thing yesterday.

The cantilever is necessary if I want the shed to be 8' wide. This will give me about 2.5' of space between the shed and the fence that is wide enough to store the lawn mower in. But I guess I can do with 7.5' width instead. Doesn't solve the floor not being flat, though.

Do I pull up the decking and fix the bulging joist problem, or do I go through with new joists on top of the decking plus shims?

I'll worry about the roof (which I'm starting to have a pretty good grasp by now) after I figure out the floor.

P.S. A lot of the trouble stems from the constantly changing shed dimensions. I started out with a 4' by 2', went all the way up to 10' by 8', all iterations in between, and finally 8' by 8'. The changes are partly due to the city restrictions on size and the largest I can get away with. I'm also constrained by the layout of the side yard, with the gate to the left of the deck, a spigot across from it, and a small tree somewhere in there. Otherwise, I would have just decked the whole thing.

[jonmulzer]

For shims when building sheds sitting on concrete blocks we always used single tabs of shingles. We would get everything level enough in the blocks that we would only have to adjust maybe a 1/4"-1/2" at most. They let you adjust things in very fine increments and should last forever.