Roof Condensation

[MichaelB]

Searched and found lots of threads on condensation but didn't see anything specific to my question.

I have a few questions about metal roofs and condensation.

1) Porch with a metal roof, when there is snow on it and it warms a bit, the porch ceiling is literally dripping water from condensation. What options are there to keep this from happening or to keep it from dripping?

2) Metal roof on a 'back room' that seems to have been built as part of the original install in 1971. It has a corrugated metal roof. The ceiling is covered with homasote and looks to have moisture issues and had some repairs. I haven't opened it up yet to see what's above it, but i'm guessing that there is insulation. I'm going to remove all the paneling and homasote from the walls and ceilings and redo the insulation. There is also water that runs down the inside siding (the wall of the actual mobile home) that I haven't yet tracked down, but thinking it's condensation from the roof/ceiling. What should i use to keep condensation from the roof from dripping onto the insulation once I redo it? I know that when new metal roofs are installed on barns/garages, there is a poly barrier used underneath it to prevent water from dripping, and assuming it runs off to the outside. Is that how mobile homes are designed?

3) General question: The ceiling of the actual mobile home has fiberglass insulation then a black fiber-like panel above the wood truss strapping, with space between it and the metal roof. Some was falling down a bit and i propped it back up as i'm having it sprayed with closed-cell foam. How does this vent and where does water/condensation go? I'm assuming the metal roof gets condensation underneath it.


Thanks in advance. Hope i didn't ask too much in one post. If so, please let me know and can create separate posts.


Michael

[Greg]

Metal roofs & condensation seem to go hand in hand, it is usually a major pain. The porch may be the easiest. I used vinyl soffit on the bottom of mine, any condensation drips on to it and with a slight pitch gust runs off to the side.
Ventilation is about the only way to prevent condensation on bare metal, Spray foam may give the thermal break to stop it.

Greg