A friend's dad stopped out and helped me today, feel like I'm ready to rock n roll now. What do you guys think? See any issues?

Lookin great.....want to see the finished pictures soon.

Looks good but your roof will leak.

Thumbs up! Just don’t use the osb to sheath the roof.

Going to do a tin roof. If I do Tin when I have rain days off I can hide out in the shed and listen to the rain on the roof.

That brings up another question, I do plan on insulating this shed, should I do plywood on the roof? Or could I just get away with out it? I had originally planned on putting OSB on the roof then a buddy said just put purlins on and put the tin straight on that.

With no sheathing or underlayment it will drip condensation on you in the mornings , lol . I know from experience.

I would use purlins with a vapor barrier. My plywood roof rotted under the tin from the condensation trapped from the tin sweating.

Do yourself a favor and wrap the WHOLE thing in reflective bubble wrap!

if you sheath it then do tin , you need to put down tar paper between , if you do purlins you need to do insulation they make a roll insulation with a thin poly layer on both sides this gets rolled over the purlins and then the steel goes down over it.

this keeps the condensation issues , and will help greatly with heat and noise

tin heats up even white tin will be 140* in the sun and 80s temps , it transfers that heat right through but a little insulation is all it takes to make the unde roof temp got from 140s to just a few degrees more than ambient air temp

No not really its a 2x14 now with the extra stud and you have just additional support with having 2 support studs on each side. Just make sure the door fits because you have an altered non-standard door size now though, that would be the only issue if there was one.

I would never use OSB for anything, I would only use real plywood especially since it can get wet, dry, get wet, dry with no issues at all. I would 100% do real 5/8 plywood on the roof(calculate snowload) and do tar paper and the tin roof over that. I had a tree come through my house, if there was no plywood it would have been far far worse and likely would have messed up way way more than it did. Your life is worth the cost of the plywood(not OSB garbage). If you use screws make sure your rubber gasket is not broken or you will get leaks.

For the insulation, you need to do some calculation on airflow through your walls, because that will determine a nice dry inside vs a stuffy, never right, damp inside. I would never use a vapor barrier anywhere in the USA, you don't need them and don't let somebody trick you. I recommend sheeps wool for the insulation, its the hands down best functional, rating, everything.

I'm going to build the doors, they will be barn style doors that open together with over 6' of total opening. That will be useful for bringing in equipment to work on or lumber to dry etc.

I'm not going to live in this and if a tree comes through it I have much bigger problems, the closest tree of any size is about 100' away. The roof is 10/12 so I'm not anticipating any problems with snow, especially with a tin roof.

I thought I had this all figured out but you guys have me rethinking this roof as far as plywood etc. I have no idea what the right thing is.

5/16" plywood? Must be a typo. You must mean 5/8".

Good catch, yes I changed it, thank you.

I'd just put up the plywood, you can use osb if your heart desires but still put tar paper and then your tin roof. It will help stiffen up your entire shed, and you'll have an additional layer of protection from the elements. Think of it like this, you already put OSB on the walls, if you weren't going to do the roof the same way, why did you do the walls that way?

as long as you cover OSB with tar paper before you put anything else over it lasts a long time , maybe not as longs as plywood but your shed is sitting on a wood foundation , it isn't going to last a century pluss but maybe 40-50 years if you keep that wood foundation dry.

the other thing is vent that at the ridge or the gables to get the heat and humidity out in the summer will make OSB last longer

lol have seen plywood blow up over night, that osb will do just fine

Osb is the debbil! Lol

Which will make the sheeting rot! It's either or!

what greencountypete said do it that way and you will be fine