Vapor Barrier for Flat Roof
Vapor Barrier for Flat Roof
(OP)
Where can I find the calculation to determine if a vapor barrier is required for a flat roof? What reference?
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Vapor Barrier for Flat Roof
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RE: Vapor Barrier for Flat Roof
15 or so years ago Here in massachusetts it was popular amongs dry-wallers to omit VBs in the ceiling, supposedly to aid in avoiding over-humidifing the living space in winter.
I put 6 MIL poly in our ceiling below the insulation anyhow. With dogs, cats and kids the doors are open so often that we get plenty/too many air changes
RE: Vapor Barrier for Flat Roof
RE: Vapor Barrier for Flat Roof
However, I doubt that the roof would be causing a uniform problem on the 3rd and 4th floor though. Basic physics check - Is the supply air temperature (i.e. grille temp) less than the dewpoint of your space. Is your space temp and humidity within spec? Is your AHU/RTU doing as it should? Has someone recently umm...messed with it?
Is outside air leaking in and condensing on the grilles? If this is happening closer to the perimeter or near doors this would be my first check.
Is there water being carried over from your coil - face velocity? If the coil is not adequately dehumidifying the air, you have another contribution to the problem. Is the moisture limited to the face of the grilles, or all through the ductwork?