I’m closing in a covered back porch to make a future office. I was hoping the insulation would stop the condensation, but as it got pretty cold last night, and warmed up this morning, the bottom of the metal panels began pouring water through the insulation.
To stop the condensation, I’m thinking I can
(1) Take up the metal panels, put plywood down over the purlins, then tar paper over the plywood, then re-install the metal panels, or
(2) Take up the metal panels, install 1/2 inch foam board insulation panels on the purlins, then re-install the metal panels.
I’ve researched a little about spray foam, but not sure how effective it would be.
Once you insulate and condition the inside air it will stop. You will be changing the dew point.
Is this location going to be in conditioned air?
Vinyl backed insulation is your best bet.
I wouldn’t let the insulation come in contact with the metal. It need to be ventilated.
Roy, my brother, the inside is conditioned and insulated (see pictures). The insulation is not contacting the the metal. There is about a 2 or 3 inch void over the insulation for air space. The metal is getting cold, then heating up from the sun in the morning, causing it to sweat. The insulation is catching the dew. I need to stop it from condensating on the underside.
Your condensation is created before the sun has a chance to hit the metal. The metal is cold and dew point is reached from within. That Batt insulation is a poor choice they allow inside temp to reach the metal causing condensation.
Just blow foam and be done with it. Ya want me to come and inspect it for ya. I will bring my Red Hat and give you one.;-);-):mrgreen:
The thing that is causing condensation is the lack of an air/vapor barrier on the warm side, most of the suggestions above will work, closed cell foam is also an air barrier, and is probably the best option, (but what about off gassing UF?) 6 mil poly over the batt insulation (on the warm side) is the cheapest, it will also require some ventilation to the exterior, so that any air that gets in the batts and under the steel roof will be outside air.