Forgot to mention that I'm concerned that if I just insulate the roof with foam board or a product like Prodex Total Insulation (http://www.insulation4less.com/prodex_Ffmf.asp) that the ridge vent and gable vents will allow so much air to escape that it won't be effective.
I'm considering finishing the ceiling by attaching horizontal 2x4's (maybe 2x6s) to the rafters at 24" on center to create a frame for hanging drywalll to the ceiling. I could then use R-19 fiberglass batts or Prodex in the ceiling and then there would be a continous air space above the insulation so the ridge and gable vents could work as intended. There are no soffit vents in the eaves. The ceiling would form a seal between the shed workspace and the shed attic. Does that make sense?
The outside walls are 8' but if I drop the ceiling where the framing meets the rafters that's only about a 7' 8" headspace. I was thinking of hanging the ceiling a little higher on the rafters to form at least an 8' ceiling. I don't plan on using the attic for storage so I don't think that would cause any structural concerns.
I'm considering finishing the ceiling by attaching horizontal 2x4's (maybe 2x6s) to the rafters at 24" on center to create a frame for hanging drywalll to the ceiling. I could then use R-19 fiberglass batts or Prodex in the ceiling and then there would be a continous air space above the insulation so the ridge and gable vents could work as intended. There are no soffit vents in the eaves. The ceiling would form a seal between the shed workspace and the shed attic. Does that make sense?
The outside walls are 8' but if I drop the ceiling where the framing meets the rafters that's only about a 7' 8" headspace. I was thinking of hanging the ceiling a little higher on the rafters to form at least an 8' ceiling. I don't plan on using the attic for storage so I don't think that would cause any structural concerns.