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John Bartlo Posted: Jan 27, 2009 03:43 PM	Gap between open cell and drywall Hi Mason. We often spray 4" of open cell in a 2x6 wall. We've got a building inspector in one of the towns around here that wanted us to spray a vapor barrier onto the foam unless we completely filled the cavity (in which case no vapor barrier was needed. My opinion is that unless there is an air leak into that cavity from the outside, there will never be a moisture problem. I'm wondering what your opinion is. By the way, all of the wall components are either moisture permeable or semi-permeable creating a flow-through structure.
William Gibson Posted: Jan 27, 2009 04:42 PM	BuffaloFoam: Where abouts are you located?
John Bartlo Posted: Jan 27, 2009 05:49 PM	Buffalo, NY DOE zone 5
William Gibson Posted: Jan 28, 2009 06:40 AM	Not for nothing but what is your reasoning that R-13 to 14 is acceptable in the State of New York? Especially in a winter climate like Buffalo.
John Bartlo Posted: Jan 28, 2009 09:17 AM	Every project we do meets code (prescriptive or ResCheck). And since it's foam it's definitely adequate. BTW, it's not as cold a climate here as most people think (<6,700 HDD)! We live next to a big lake that moderates the temperature nicely. It rarely gets below zero here.
William Gibson Posted: Jan 28, 2009 09:41 AM	Great, Rescheck is a good savior. What do you use for ceiling slopes and/or attics? If foam, what kind and thicknesses?
John Bartlo Posted: Jan 28, 2009 12:00 PM	Where are you from Newman?
mason Posted: Jan 28, 2009 12:43 PM	In Buffalo, you would require a vapor retarder element over the open cell foam. This can be a coating as well as a film type vapor retarder. Ask your supplier for their recommendation.
William Gibson Posted: Jan 28, 2009 12:56 PM	Albany Area. We stick to code in walls. Only place where we work against code, or utilize ResCheck is with ceilings and/or attics when using 2 lb. CC. Reason why I called you out on that is we wouldn't feel comfortable giving the customer 4" of 0.5 lb Open Cell whether it looks good on ResCheck or not. We fill the 2x6 cavity, scarf it, apply our vapor barrier and collect the check.
John Bartlo Posted: Jan 28, 2009 01:54 PM	So Mason, back to my original question, do I need a vapor barrier even if I do a full fill of the 2x6 cavity? Thanks.
John Bartlo Posted: Jan 28, 2009 01:59 PM	Newman: we typically install 6-7" half pound in flats. In existing homes we typically spray right to the roofdeck. In the typical roofdeck application we don't use a vapor barrier. I know we're right on the border of being cold enough to theoretically warrant one, but until I hear firsthand of a roofdeck moisture problem I don't find it necessary. Open cell has been installed in roofdecks around here without a vapor barrier for over a decade. Since the market won't bear the cost anyway, it makes the decision even easier. Aside from our install business we distribute product across most of upstate and I find as you go east people are much more educated about foam and are more willing to pay higher prices for more Rs and vapor barriers.
mason Posted: Jan 28, 2009 03:45 PM	Open cell foam has a perm rating of well over 10-15 for a 3.5 inch thick application. 6 inches may take it down to the 7-12 perm rating. Still not sufficient without a coating or film in the cold weather. Condensation is likely if the inside humidity gets in the 40 to 50% range.
William Gibson Posted: Jan 28, 2009 04:04 PM	Mason: Is 10" more like it?
John Bartlo Posted: Jan 28, 2009 04:30 PM	Newman, what brand of spray on vapor barrier do you use? Thanks.
andy buff Posted: Jan 28, 2009 08:53 PM	were do you distribute upstate.and what are you sellin
William Gibson Posted: Jan 29, 2009 06:59 AM	Buffalo: We haven't ever used a spray on vapor barrier. Fact is we never had to spray open cell in the ceiling. If we had to, we'd spray 10" of OC and we'd use TPR coating. We've only sprayed 2lb. for ceilings, and we've only sprayed .5 lb. in wall cavities, filled, and covered with a poly vapor barrier.
John Bartlo Posted: Jan 29, 2009 08:41 AM	Skinny: We distribute LaPolla (www.lapolla.com) out of Buffalo. We Have another distributor in Syracuse and I'm pretty sure there is a guy between Albany and NYC.

Author

Comments

John Bartlo

Posted: Jan 27, 2009 03:43 PM

Gap between open cell and drywall

Hi Mason. We often spray 4" of open cell in a 2x6 wall. We've got a building inspector in one of the towns around here that wanted us to spray a vapor barrier onto the foam unless we completely filled the cavity (in which case no vapor barrier was needed. My opinion is that unless there is an air leak into that cavity from the outside, there will never be a moisture problem. I'm wondering what your opinion is. By the way, all of the wall components are either moisture permeable or semi-permeable creating a flow-through structure.

William Gibson

Posted: Jan 27, 2009 04:42 PM

BuffaloFoam:
Where abouts are you located?

John Bartlo

Posted: Jan 27, 2009 05:49 PM

Buffalo, NY DOE zone 5

William Gibson

Posted: Jan 28, 2009 06:40 AM

Not for nothing but what is your reasoning that R-13 to 14 is acceptable in the State of New York? Especially in a winter climate like Buffalo.

John Bartlo

Posted: Jan 28, 2009 09:17 AM

Every project we do meets code (prescriptive or ResCheck). And since it's foam it's definitely adequate. BTW, it's not as cold a climate here as most people think (<6,700 HDD)! We live next to a big lake that moderates the temperature nicely. It rarely gets below zero here.

William Gibson

Posted: Jan 28, 2009 09:41 AM

Great, Rescheck is a good savior.
What do you use for ceiling slopes and/or attics? If foam, what kind and thicknesses?

John Bartlo

Posted: Jan 28, 2009 12:00 PM

Where are you from Newman?

mason

Posted: Jan 28, 2009 12:43 PM

In Buffalo, you would require a vapor retarder element over the open cell foam. This can be a coating as well as a film type vapor retarder.

Ask your supplier for their recommendation.

William Gibson

Posted: Jan 28, 2009 12:56 PM

Albany Area. We stick to code in walls. Only place where we work against code, or utilize ResCheck is with ceilings and/or attics when using 2 lb. CC.

Reason why I called you out on that is we wouldn't feel comfortable giving the customer 4" of 0.5 lb Open Cell whether it looks good on ResCheck or not. We fill the 2x6 cavity, scarf it, apply our vapor barrier and collect the check.

John Bartlo

Posted: Jan 28, 2009 01:54 PM

So Mason, back to my original question, do I need a vapor barrier even if I do a full fill of the 2x6 cavity? Thanks.

John Bartlo

Posted: Jan 28, 2009 01:59 PM

Newman: we typically install 6-7" half pound in flats. In existing homes we typically spray right to the roofdeck. In the typical roofdeck application we don't use a vapor barrier. I know we're right on the border of being cold enough to theoretically warrant one, but until I hear firsthand of a roofdeck moisture problem I don't find it necessary. Open cell has been installed in roofdecks around here without a vapor barrier for over a decade. Since the market won't bear the cost anyway, it makes the decision even easier.

Aside from our install business we distribute product across most of upstate and I find as you go east people are much more educated about foam and are more willing to pay higher prices for more Rs and vapor barriers.

mason

Posted: Jan 28, 2009 03:45 PM

Open cell foam has a perm rating of well over 10-15 for a 3.5 inch thick application. 6 inches may take it down to the 7-12 perm rating. Still not sufficient without a coating or film in the cold weather. Condensation is likely if the inside humidity gets in the 40 to 50% range.

William Gibson

Posted: Jan 28, 2009 04:04 PM

Mason:
Is 10" more like it?

John Bartlo

Posted: Jan 28, 2009 04:30 PM

Newman, what brand of spray on vapor barrier do you use? Thanks.

andy buff

Posted: Jan 28, 2009 08:53 PM

were do you distribute upstate.and what are you sellin

William Gibson

Posted: Jan 29, 2009 06:59 AM

Buffalo:
We haven't ever used a spray on vapor barrier. Fact is we never had to spray open cell in the ceiling. If we had to, we'd spray 10" of OC and we'd use TPR coating.

We've only sprayed 2lb. for ceilings, and we've only sprayed .5 lb. in wall cavities, filled, and covered with a poly vapor barrier.

John Bartlo

Posted: Jan 29, 2009 08:41 AM

Skinny: We distribute LaPolla (www.lapolla.com) out of Buffalo. We Have another distributor in Syracuse and I'm pretty sure there is a guy between Albany and NYC.

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