I have a metal roof. I only use heat about about 4 or 5 days a year (when it gets below 60). I only use the central air about 30 days a year. The rest of the time my windows are open because I get a nice breeze. I am planning to install drywall on the walls and ceiling. It is quite a bit hotter near the ceiling, because I can tell this when I am on a ladder changing a light bulb. I would like to put insulation in the ceiling, but it would be very difficult to vent it. Since I do not have warm moist air hitting a cool surface will I have a moisture problem if it is not vented? Or will the change in temperature at night be a problem as sometimes there is condensation on the surface of the metal roof in the morning. I know spray foam would work, but the cost is too high. Since I do not use heat or air much, will it be a problem with fiberglass insulation and no venting?

It is totally normal for the air to be much warmer near the ceiling in a cathedral ceiling due to warm air raising. Insulation basically keeps the cold out or keeps the hoy out. It sounds like you are close to a great balance but might save a few days of AC if you vent. Venting a cathedral ceiling is frequently difficult because many have windows that reach up to the peak. How is you place constructed near the peak, can you install a window or louvered vent?

It would be very difficult to install a window or vent. I wanted to know if I will have a moisture problem (then rotten wood) if I do not vent, since I do not use heat or AC very much?

Sorry but I'm no expert in your climate, you get more heat and humidity than Chicago. I'd install ceiling fans or keep my furnace blower motor running to keep air moving. Circulation helps more than any other thing.

How tall is the ceiling? Good ceiling fans mounted on a cathedral ceiling will help greatly with HVAC.

Thank you for yout reply. We already have ceiling fans (even 3 of them in the larger rooms. You are right they help, but since we are planning to drywall we wanted to know about the venting before we did it.

Depending on the height of the ceiling I may recommend specific fans that will do more.

This is just had a thought but I think they make a vent cap for the ridge of a roof

Could you make a vent cap that would be weather resistant -- draw heat out top

Or put louvered fans in ends of house near peak -- draw heat off ceiling

Thank you for your reply, but because it is a cathedral ceiling and the new drywall will be right against the rafters the roof vent would have to be the entire length of the roof. There would have to vents at the top of each rafter and at each end. That is why I wanted to know if I needed venting due to the very limited time I use AC or heat.