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Posted: Jan 27, 2011 06:27 AM	Open or Closed is the question I have had numerous contractors out to give me estimates on SPF my attic. (I have ice damn problems) Some say, roof line, some say attic floor. For me I could go either way as I understand the reasons for both. However, there is almost as split on open vs closed cell on either the roof line or attic floor. With everything I have read about these two types of foam, I personally think closed cell is the way to go since it is a vapor barrier and open cell is not. I am also told (by one contractor) 2" closed cell and the rest open cell. Here are my concerns: 1. R-Value 2. Humidity (live in NJ and summers are wet/hot) 3. roof decking and shingles are brand new (4 years old) and I do not want failure 10 years from now. Any input would be appreciated as I want to do this right (insulate the attic and hire the correct contractor for my application) and have no issues down the road. Thanks
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Jan 27, 2011 06:50 AM	You can't go wrong with either product. I personally like the open cell because wood is open cell and it's less expensive. In addition to that, if you ever have a roof leak, you'll know it because it will leak through the foam. No issues with vapor barriers and the open cell foam and I've been doing this for the past 8 years, even up here next to Lake Ontario and al of the Finger Lakes. No issues with the roof shingles ever having an issue. As a matter of fact, some like us spraying the back side of the roof to help melt the shingles into place. It prevents the wind from getting under the shingles and ripping them off. Hope this helps! Jim
mason Posted: Jan 27, 2011 07:49 AM	I agree that both will work. Adding to Jim's comment, closed cell SPF will stop water from entering the building by sealing cracks and crevicess within the roof deck sheathing. So with the open cell foam you would more readily see roof leaks, with the closed cell you would have fewer leaks that get into the building. In your area check to see if you need a vapor retarder over the open cell foam. An intumescent coating might fit the need depending on its physical properties.
mason Posted: Jan 27, 2011 07:53 AM	Check out my website article "Learning the Difference Between 1/2 lb and 2 lb density SPF" at masonknowles.com
Posted: Jan 27, 2011 09:08 AM	Thanks for the replies. I appreciate it and it has made me feel better and more knowledgeable about Open Cell!

Author

Comments

Posted: Jan 27, 2011 06:27 AM

Open or Closed is the question

I have had numerous contractors out to give me estimates on SPF my attic. (I have ice damn problems)

Some say, roof line, some say attic floor. For me I could go either way as I understand the reasons for both. However, there is almost as split on open vs closed cell on either the roof line or attic floor.

With everything I have read about these two types of foam, I personally think closed cell is the way to go since it is a vapor barrier and open cell is not. I am also told (by one contractor) 2" closed cell and the rest open cell.

Here are my concerns:

1. R-Value
2. Humidity (live in NJ and summers are wet/hot)
3. roof decking and shingles are brand new (4 years old) and I do not want failure 10 years from now.

Any input would be appreciated as I want to do this right (insulate the attic and hire the correct contractor for my application) and have no issues down the road.

Thanks

jimcoler

I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs.

I've expanded my knowledge into t

Posted: Jan 27, 2011 06:50 AM

You can't go wrong with either product. I personally like the open cell because wood is open cell and it's less expensive. In addition to that, if you ever have a roof leak, you'll know it because it will leak through the foam.

No issues with vapor barriers and the open cell foam and I've been doing this for the past 8 years, even up here next to Lake Ontario and al of the Finger Lakes.

No issues with the roof shingles ever having an issue. As a matter of fact, some like us spraying the back side of the roof to help melt the shingles into place. It prevents the wind from getting under the shingles and ripping them off.
Hope this helps!
Jim

mason

Posted: Jan 27, 2011 07:49 AM

I agree that both will work. Adding to Jim's comment, closed cell SPF will stop water from entering the building by sealing cracks and crevicess within the roof deck sheathing. So with the open cell foam you would more readily see roof leaks, with the closed cell you would have fewer leaks that get into the building. In your area check to see if you need a vapor retarder over the open cell foam. An intumescent coating might fit the need depending on its physical properties.

mason

Posted: Jan 27, 2011 07:53 AM

Check out my website article "Learning the Difference Between 1/2 lb and 2 lb density SPF"
at masonknowles.com

Posted: Jan 27, 2011 09:08 AM

Thanks for the replies. I appreciate it and it has made me feel better and more knowledgeable about Open Cell!

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