new standing seam metal roof ?s
- Thread starter ak9
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tlbuser
Veteran Member
right, no clue why i put it backwards
dave1949
Super Star Member
A puzzle!
One idea; if there is dew on the exterior surface of the roof, when the sun strikes that, it may cause evaporation cooling for a few minutes. This would in turn cause warm moist air below the roof to condense.
Dave.
The price that I posted is material onlypans $2sq ft & w/ trims$2.28 and no gutter or underlayment . I was triing to find synthetic underlayment locally but,no find so I ended up puttin 30# felt. When I tear off the upper part I'll use that TITANIUM UDL as my underlayment.This type of staning seam steal roofing does not use the "crimper" method It snap locks together.Each pan is screw down on one side and the other snaps over the adjacent pan..Easy system to install I've seen it done b4 never done myself though.I had another Quote material only for $2.50 /sq ft ..35+ year waranty on paint and 50year on metal .From what I've read about it solid deck is best ply or osb , felt or synthetic underlayment is required And there is prepunched anchor points.
ak9
ak9
What puzle? it happens whenever the humidity is above about 50%, been doing it regularly for over 40 years.
got nothing to do with "dew" on top the porch is under a canopy and rarely if ever has dew on it, it sweats in cooler weather on the underside when the top is warmed. What do you call it if it's not condensation?
A quick Google search will show the issue is not at all uncommon
It seems to me that if there is not enough ventalation in enclosed situations that moisture will accumulate and cause mold or worse.
dave1949
Super Star Member
From your description, I am picturing a metal porch roof that is mostly exposed on the underside. In other words, standing on the porch, you can look up and see the underside of the metal roof. ??
Dave.
you guys are missing the point entirely by convoluting the issue, it's not about the science that causes sweating, the fact is that metal roofs sweat period.
I think some of you guys would argue the fact that the Sun rises in the East:laughing:
metal roofs sweat - Google Search
Inclosing the undersides does not prevent sweating, if moisture (humidity) is there it will condense under the right conditions.
I have seen old metal roofing that was placed directly on top of roofing felt, after only a few years the felt has disintegrated to nothing but brittle flakes and allowed moisture to cause both mildew and material damage to the plywood decking beneath.
I think some of you guys would argue the fact that the Sun rises in the East:laughing:
metal roofs sweat - Google Search
Inclosing the undersides does not prevent sweating, if moisture (humidity) is there it will condense under the right conditions.
I have seen old metal roofing that was placed directly on top of roofing felt, after only a few years the felt has disintegrated to nothing but brittle flakes and allowed moisture to cause both mildew and material damage to the plywood decking beneath.
scgargoyle
Gold Member
- Joined
- Dec 18, 2007
- Messages
- 364
I was always told to 'double strap' a metal roof. put a barrier on the sheathing, fasten vertical strips through the sheathing into the rafters, then put crossways straps (purlins) on top. Fasten the tin to the purlins. The purlins run the right way to fasten the tin, and the vertical strips give condensation a way to drain off of the roof. I've also been told that this method will result in more condensation because of the air flow, but will also get rid of the condensation quickly, whereas tin applied directly to the sheathing will trap moisture, since there is little airflow. Many barns have been built with no sheathing- and they definitely drip water inside, depending on the atmospheric conditions. I have to admit- At this point, I'm not sure which method is better. I need to decide, though, as I'll be roofing a barn in another month or so!
Question- Why are the materials for standing seam so much more? It's usually at least double, just for the materials.
Question- Why are the materials for standing seam so much more? It's usually at least double, just for the materials.
