# Condensation Issure and Resolutions for Single Ply Systems



## Oasis Roofing (Feb 21, 2012)

Pvc roofing is like putting a plastic bag over a home so what do you do to make condensation not a issue. I personnaly try to install ridge vent and as many two condensation vents as needed, and high quality vapor barrier, also really pay attention to vent that may have air gaps, and leaks.

Thanks,

Oasis Roofing & Construction, Inc


----------



## Grumpy (Oct 29, 2008)

If it is a cold deck design, meaning that the ceiling is insulated and the roof is not, simple install http://www.commercialproductsgroup.com/Libraries/Product_Literature/VENTS_and_BREATHERS.sflb.ashx a two way breather. 

If it is a warm deck design do not install a 2 way breather. And do not install ridge vent on roofs less than 3/12 in pitch.


----------



## shazapple (Dec 3, 2010)

I can't see those 2 way breathers flowing much air. You would probably be better off with some sort of gravity vent (passive louvred box like thing)


----------



## Grumpy (Oct 29, 2008)

The smaller size are for venting lay overs, the larger are for venting "Attic" space. They work just fine when you install adequate ammount. Just like any ventilation, do the math first.


----------



## shazapple (Dec 3, 2010)

I'm kindof wary, as I can't seem to find their net free vent area listed anywhere. They may be 6" diameter but there's no guarantee they flow that much.


----------



## Grumpy (Oct 29, 2008)

I've read specs saying on lay-overs to use 1 of the smaller 1 way breathers per 10 squares. That's a modofied bitumen spec though, which honestly never made sense to me since mod bit should be fully adhered, but what ever. 

I know this is not scientific, but generally speaking on a 1,000 sq ft foot print, I would see 2 of the larger 6" 2 way vents. That doesn't mean it's right or wrong, just that is what is common practice (from the roofers that actually ventilate) in my area. 

Contact the vent manufacturer and see if they have a spec sheet on their products with NFA, and contact the single ply manufacturers you work with and ask if they have a NFA recomendation.


----------

