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Posted: May 17, 2009 03:02 PM
One ways
How effective can one way vents be in removing moisture from a roof that either has foam on top?

I am bidding on a job with multiple blisters on a foam roof that is about 10 years old and saturated with water throughout. The only thing that I can figure from looking at the roof was that it was either foamed over decking that had condensation or sprayed over liquid tar or perhaps was even off ratio at the time it was sprayed since it is so wide spread..

If I get the job, we are going to do a full tear off of the foam, but when I was taking core samples the other day, a national sales rep was there for another foam roofing company and they were only quoting on cutting the blisters out, scarfing and then foaming.

Either way, are one way vents that effective in pulling out condensation from a saturated roof?
Posted: May 21, 2009 10:31 PM
22,000 sq. ft of blistered saturated foam that I bid to take off, remove any other saturated decking and re-foam (1.5") and coat (30 mil). When I say blistered, I mean 6-8 inches above the rest of the roof. When you step on them, water would shoot up over my head and I am 5'9".

I should have known something was wrong when I showed up the day of the sealed bid to look at the roof one more time and my core samples were the only ones done with no one tampering.

Bottom line, my bid was $92K with tear off and someone got the job for $58K. I guess there will either be one ways through out the roof or there will be blisters from foaming over wet foam in another year.

All right, I finished feeling sorry for myself. Time to move on.
Terrance Harris
Posted: May 22, 2009 03:09 PM
Do not put too much faith in one way vents. Your bid was right. Walk away and don't look back. The owner of the building loses. The failure will continue and spray foam roofing gets another bad mark.
Dennis Davidson
Posted: Jun 08, 2009 08:32 AM
I've seen many roofs like this. Sometimes you can scarf, remove isolated areas and re-foam. It all depends on how much of the foam is saturated and needs removed. The only way to know is to infrared scan AND multiple cores. One way vents on BUR will only dry about 1 sq. but won't work over foam at all.
Gerry Wagoner
Posted: Jun 09, 2009 01:41 PM
ABout $5 a ft² is in the ballpark.

One ways will do a better job if they can "communicate" with each other. If not, the one-ways are well limited.

(checking in from Oslo),

Posted: Jun 09, 2009 11:32 PM

Got to be cooler than South Louisiana!

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