[Patty Foster]

I am going to be building a 10' x 12' shed with a 2/12 pitch of the 10' side. I am getting conflicting answers as to spacing and material of the rafters, stud walls and floor joists. The flooring I plan on using is 23/32" T&G OSB, a riding lawn mower will be stored in it, roofing I have had both 3/8" and 23/32" recommended. Roofing will be asphalt comp. shingles. Wall sheathing as been recommended both 3/8" and 7/16" OSB. I will siding with 7 1/4" cement composite lap siding. I live in Idaho where we do not have extreme winds and snow load doesn't exceed 4 inches and that is rare. Building permits are not required for any structure less than 200 sq. ft.

 

[joed]

2/12 is too low of a pitch for shingles. You will need roll roofing.

 

[craig11152]

As to spacing go 16" rather than 24". The cost difference for a small shed is negligible. I would use 2x6 rafters and 2x8 floor joists. Your shed is small enough that over building won't cost more than an extra 30-40 bucks.

 

[joecaption]

Big mistake to not have a steeper pitched roof.The steeper the pitch the longer the roofing will last and far less likely to leak.
Most shingle manufactures would not warranty shingle installed on that low a pitch.
Make all your studs and joist 16" on center.
Used 3/4" T X G Advantech for the subfloor, 1/2 OSB or plywood on the walls and roof.
Never once have I seen or used 3/8 for any of it.
Make sure the roof has an over hang on all sides for far less siding and door rot issues.
For the trim I'd be using PVC lumber, never going to rot or need painting.
Do not use the Hardee trim, it's a royal pain to work with and nail.

 

[craig11152]

2/12 is too low of a pitch for shingles. You will need roll roofing.

while 2/12 is a bit low its within guidelines and since this is an (presumably) unheated shed I don't see a huge issue.

edit: GAF, Owens Corning, Certainteed, Atlas and Tamko all allow shingles on a 2/12 with various precautions. Most of those extra precautions can pretty much be ignored for an unheated shed to store a lawn mower.

 

[MushCreek]

Be careful when laying out the T&G OSB for the floor. It's not a full 48", like regular plywood, but has a net of only 47-1/2". If you make your floor exactly 10 X 12, it will come up just a little short.

Around here, walls and roofs are generally sheathed with 7/16" OSB, and it is much cheaper than other thicknesses because of this.

 

[craig11152]

an alternative floor might be a pressure treated deck material. It won't much care about moisture or temperature extremes.

 

[carpdad]

I think you need to know the weight of the mower. As well as how high your roof and the door should be to ride it into the shed. That should determine the floor construction. The floor joists, if not sitting on solid base, will be on the perimeter beams, and neither the joists nor the beams should bend under the weight-over long term. I am imagining pacted gravel base, extending 1-2 feet enclosed by pt rail fence, 4x4 pt floor frame (maybe 12" apart), and 2 layers 3/4" pt ply. I don't know what your mower needs for a floor. Its wheels will be on the floor, most likely over 4 points on the floor plywood, so the weight will be concentrated over small areas, not evenly over the entire floor. You also may want concrete slab. Plywood could become quickly damaged if the mower drips fluids or water.
You may want to post this question in lawn section for real life experiences.
For such a shed, wall spacing of 24" and 3/8" ply is fine. But closer spacing and 1/2" ply min is better because whatever cladding you use, there will be less waste as well as more nail holding capacity. If you can plan to nail into the studs, you may skip the underlayment.
If you want 2:12 roof, it's better to use the roll roofing. For small shed, you can nail the perimeter instead of gluing the whole roofing. All nails will go through the roof deck. You may hit your head on the nails if the roof is too low. The rolls also come in self stick.

 

[craig11152]

good points on the weight of the lawn mower.
Most riding mowers weight between 500 and 800 pounds. Of course the wheel weight is not evenly distributed but even if 600 pounds of an 800 pound mower is on the front tires that's 300 pounds per tire on the front and 100 per on the back.

But if the OP has a monster mower ignore my guesstimates. :wink2: