metal roof sweating

I have a metal roof that is sweating, this is a small cabin I built this yr., Only started this condensation a couple weeks ago when it turn cold. I have R-19 insulation in ceiling , the metal was laid over 1x4's spaced 2 ft apart, any suggestions? thanks

 

What's the rh in the home and what part of the country do u live in

 

Add attic ventilation.........

 

I live in middle tn., 3 days ago I installed 2 gable vents, 15"x20"., it seems to have helped. The cabin has no soffit so would anyone know if I install some of the small hooded vents along the lower part of the roof, if this would vent to the gable vents just as soffit vents would? I was told that a ridge vent would not vent right with the gable vents. thanks for any help
The cabin is only 683 square feet with a 5/12 pitch

 

Lower vents might help but I would a bit apprehensive to cut holes in the tin roof. Is this roof the same corrugated material that is used for pole barns? If so, were the holes filled on the corrugation?
___/---\___/---\___
..... Hole.... Hole

 

Is this roof only laid over the 1x4's? No substrate and no felt? You may be under the same codes we are. We have to deck the entire roof with a substrate...OSB, plywood. Then felt. 1x4's are then added to allow for under ventilation of the metal. Don't cut unnecessary holes in an otherwise non leaking roof system. I am interested, as Scott is, about how lower edge of the metal was addressed. Did they use foam blocks? How much of an overhang did you allow?

 

the roof was laid over 1x4's no OSB or plywood . the rafters are laid to the edge of the top plate. the metal overhangs 3" from outside edge of wall. the corugated holes were not block. I was told this would allow ventilation. I guess no larger than the cabin is (683 sq ft) I could remove the metal and add OSB and felt (when it warms up a little) If this would help. The attic has 19R insulation and under that a moisture barrier was laid. But until a few days ago there was no attic ventilation except the holes on the lower edge of the metal( corrguated holes) should these be Filled ?

 

Not to mention excellent places for birds/bats to nest!

I'd go ahead with your plan, remove the metal, sheath the roof, #30 felt, etc. That way if/when the metal sweats the sheathing will be protected and it can drain to the outside. Foam closure can be placed under the metal as you reassemble so that you aren't providing habitat for the wildlife. A roof that small should probably be vented with gable end vents.

 

Your lower holes would allow all the lower venting you need IMO. The addition of the gable vents gives the warmer moist air someplace to get out of the attic.

I, personally, would not add plywood or OSB if the roof is solid. While the addition of the sheathing has some R value the only thing it will change is condensation would form on the underside of sheathing instead of the metal. The issue is the air in the attic is warmer then the outside air and the moisture condenses on the under side of the roof.

I would also be a little concerned about critters and insects. Perhaps some type of screening would prevent that

 

Tolyn, thanks for the information. The holes have a black mesh screening as also the ridge cap. it came in a 50 ft roll from the metal company. Your thoughts on my venting was as mine, The sweating is about gone now that I have installed the 2 gable vents.