I'm building a 16 ft x 16 ft shed and I'm not exactly sure how to frame the roof for it. I'd like to have only half of the shed to have ceiling joists to act as a loft to store lumber and other things. The other half will be open without ceiling joists or collar ties to give me maximum ceiling height and easy access to pulling down long lumber from the loft. I'm looking at a 6:12 slope with a one foot overhang. If I'm calculating correctly, the rafters should be just about 10 ft long, and I will be doing 16" oc. What I'm trying to figure out is how to size the rafters and ridge beam since it will provide some structural support. We do get some snow here, so that needs to be figured in as well. Any help would be great!
You have nothing but options and you should Google-Image "Shed Roof Framing" or watch some YouTube videos. You can quite literally do absolutely everything out of just 2x4's.
But, for a simple old timey setup. 2x8's (the 8 times 1.5) for the rafters and a matching 2x8 ridge beam setup...beam means more than 1. Given the building length, I'd go with a Double 2x8 ridge beam instead of a ridge plate (plate means 1).
For the storage loft, 2x4's are probably just fine and even overkill. The loft's end beam (2 or 3 2x4's, for the sake of headroom and uniformity) would either go on top of the walls' Double Top Plate over Doubled wall studs or go under the Double Top Plate on shortened Doubled wall studs.
For supporting the ridge beam, a Doubled 2x4 post down to the walls' Double Top Plate is solid. This, of course, should be in perfect alignment with (or sit on top of) the loft's beam and its Doubled wall studs.
For overall longevity, I now prefer the old timey wind-bracing stud chunks in every corner and liberal rafter blocking to accommodate non-structural forever sheathing of the walls and roof, known by me as Cement-Board. Of course, great as a roof deck, but no more replacing the bottom 2-feet of exterior walls. I even put it under my floor framing to keep out pests.