Several years ago I had a porch with a slanted ceiling changed into a 3 season sun room. There is a gas fireplace which is turned off. The ceiling and room are paneled. No windows or skylight in ceiling. The room can get quite warm on a sunny winter day. Now, when it warms up, water starts leaking from the ceiling and above the window (doubled paned). This has happened even when there wasn't snow on the roof. Insulation was put on the ceiling before the paneling was applied, but evidently not enough. Is there any kind of roof protection I can have installed to prevent such leaking? This winter I didn't heat the room at all. Any suggestions? Thank you.

If it happened when there was no snow on the roof, what would have been the water source? Maybe it isn't a leak at all, but condensation within insulated but unventilated spaces between rafters. When you installed the insulation and ceiling, did you also install soffit vents and a ridge vent? If not, then that might be the source of your water.

From your statement "when it warms up" leads me to believe Richard is right about condensation. Warm, moist air from indoors may be leaking through the ceiling and insulation, or even from inside the house/porch common wall. When it hits the cold roof sheathing above the insulation it condenses, freezes, and then thaws when it warms up.

My best GUESS is that whoever installed the insulation used fiberglass batts with foil or paper face and relied on that as the air barrier.

I suspect you will need to remove the ceiling (at least its panel and easy to do)and probably have to replace the insulation. While the insulation is out, look for air leaks. A blower door will help find the leaks. Once everything is sealed, re-insulate, install a continuous air barrier, and put the ceiling back up.

As Richard says, also make sure the space is correctly ventilated. I would also make sure you're not facing a double whammy and check for roof leaks. Good Luck