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jeff macfarland Posted: Apr 28, 2008 11:59 PM	Should I go closed cell? I'm in the process of a major remodel to our 1887 home. I'm a DIYer (don't hold it against me), but I've opted to let the pros insulate it. However, I make it a point to do my research. Haven't gotten my bids yet, but the one guy I've talked to does all open cell, 3 inches in the walls, 5 in the roof. This is obviously good for his bottom line, and my wallet. But I am left wondering what will really be best for my house--might as well do it once and do it right. I can't find any clear, definitive answers about closed vs. open cell and nothing but arguments about where to put it (roof or walls or both for which type). And after researching the cost of materials and board feet coverage with the difference in R-value, I estimate it would only take one more batch to get equal or better R-values with just a little bit more foam. Here are my own figures: It's a big house and garage with living space above the garage. With the rooflines, ridge board, high ceilings, 6 inch studs, etc. I've got 8700 ft^2 to cover, about 2800 of that is roof. if open cell I could do 4 inches in the house and 3 inches in the garage, could go as much as 7 inches in the attic and come out at 45,000 board feet or about 3 batches of foam from what I've read about coverage. I get r-16, r-12, and r-28 respectively. if i go closed cell, i could do 2.5 in all the walls, go open cell in the roof at 5-6 inches. I get about 16,500 board feet in 2# foam, and 17-18000 board feet 0.5# in the roof. I get r-17.5 in all the walls, and r-24 in the roof. That's about 3 batches of 2# and 1 batch of 0.5#. I lose a little r-value in the roof, but get a vapor barrier and superior blockage of air infiltration in all the walls as well as higher r-value there. So what should I do? Do my figures look right? Would I be better off with closed cell and if so where should it go, walls, roof, everywhere? Last question: has anyone ever layered closed and open in the roof? Enough closed to get the vapor barrier and the spray open behind it to fill up the cavity? Just wondering. Thanks in advance. Jeff
Lane Hogstad Posted: Apr 29, 2008 11:04 PM	Both are great products use the best contractor and you won't go wrong
Gerry Wagoner Posted: Apr 30, 2008 12:48 PM	Hi Jeff. There are four primary reasons to choose closed-cell foam in a wall assembly. 1) vapor barrier 2) strength 3) don't have to fill the stud cavity 4) higher R-value That said, I recommend 2.5" - 3" in your studwalls (2.5 in 2x4, and 3 in 2x6). In the attic, 7-8" of open cell should do the job. Have fun, oG
Rob Granger Posted: Apr 30, 2008 10:16 PM	Ok Olger, I have to ask, why the difference. 2.5 inches in a 2x4 and 3 inches in a 2x6
Gerry Wagoner Posted: May 01, 2008 01:03 PM	Due to the undulations in spray foam, leaving a 1" gap in 2x4's reduces or eliminates closed-cell foam trimming (a daunting job by any measure). 2x6's just have more room to work with. go gettum, oG
Posted: May 02, 2008 08:26 PM	i too prefer to shoot to a 2.5" lift in the 2x4 sidewall....this will xceed an r19 batt in performance when the structure is under adverse conditions..... if a 3" lift or full cavitiy is requested... the customer will pay for the additional depth as well as the labor factor for trimming and removal...time is money... i see many more prints spec'd r-19 cc in 2x4...the architects and designers are getting it!!!REJOICE!!!but i make them pay for the 3"build,,,with proper education you can save them $$$ and sell the 2.5" lift and still give them the performance they need...(seems i remember 2.5" being the "sweet spot" for the consumer,,but i imagine that is changing to our advantage as the prices of operating our structures continue to rise...again,,REJOICE!!!) so,,yes,,,i "sell" a 2 3/4" (+/- 1/4") in either a 2x4 or a 2x6 cavity for an r-19 nominal,,,and i err to the side of the consumer in the 2x6 application,,,(hold on the phones ringin,,,get it??)...and i will deeply discount the 4th inch just to get the added performance,,,those folks will luv our product and tell everyone about you....particularly when it is REAL hot or REAL cold and every one else is bitchin... i hope this helps,,,have a great weekend and take some time to hug your babies... 'dude ;)

Author

Comments

jeff macfarland

Posted: Apr 28, 2008 11:59 PM

Should I go closed cell?

I'm in the process of a major remodel to our 1887 home. I'm a DIYer (don't hold it against me), but I've opted to let the pros insulate it. However, I make it a point to do my research. Haven't gotten my bids yet, but the one guy I've talked to does all open cell, 3 inches in the walls, 5 in the roof. This is obviously good for his bottom line, and my wallet. But I am left wondering what will really be best for my house--might as well do it once and do it right.

I can't find any clear, definitive answers about closed vs. open cell and nothing but arguments about where to put it (roof or walls or both for which type). And after researching the cost of materials and board feet coverage with the difference in R-value, I estimate it would only take one more batch to get equal or better R-values with just a little bit more foam.
Here are my own figures:

It's a big house and garage with living space above the garage.
With the rooflines, ridge board, high ceilings, 6 inch studs, etc. I've got 8700 ft^2 to cover, about 2800 of that is roof.

if open cell I could do 4 inches in the house and 3 inches in the garage, could go as much as 7 inches in the attic and come out at 45,000 board feet or about 3 batches of foam from what I've read about coverage. I get r-16, r-12, and r-28 respectively.

if i go closed cell, i could do 2.5 in all the walls, go open cell in the roof at 5-6 inches. I get about 16,500 board feet in 2# foam, and 17-18000 board feet 0.5# in the roof. I get r-17.5 in all the walls, and r-24 in the roof. That's about 3 batches of 2# and 1 batch of 0.5#. I lose a little r-value in the roof, but get a vapor barrier and superior blockage of air infiltration in all the walls as well as higher r-value there.

So what should I do? Do my figures look right? Would I be better off with closed cell and if so where should it go, walls, roof, everywhere?

Last question: has anyone ever layered closed and open in the roof? Enough closed to get the vapor barrier and the spray open behind it to fill up the cavity? Just wondering.

Thanks in advance.

Jeff

Lane Hogstad

Posted: Apr 29, 2008 11:04 PM

Both are great products use the best contractor and you won't go wrong

Gerry Wagoner

Posted: Apr 30, 2008 12:48 PM

Hi Jeff.

There are four primary reasons to choose closed-cell foam in a wall assembly.

1) vapor barrier
2) strength
3) don't have to fill the stud cavity
4) higher R-value

That said, I recommend 2.5" - 3" in your studwalls (2.5 in 2x4, and 3 in 2x6).

In the attic, 7-8" of open cell should do the job.

Have fun,

oG

Rob Granger

Posted: Apr 30, 2008 10:16 PM

Ok Olger,
I have to ask, why the difference. 2.5 inches in a 2x4 and 3 inches in a 2x6

Gerry Wagoner

Posted: May 01, 2008 01:03 PM

Due to the undulations in spray foam, leaving a 1" gap in 2x4's reduces or eliminates closed-cell foam trimming (a daunting job by any measure).

2x6's just have more room to work with.

go gettum,

oG

Posted: May 02, 2008 08:26 PM

i too prefer to shoot to a 2.5" lift in the 2x4 sidewall....this will xceed an r19 batt in performance when the structure is under adverse conditions.....
if a 3" lift or full cavitiy is requested... the customer will pay for the additional depth as well as the labor factor for trimming and removal...time is money...
i see many more prints spec'd r-19 cc in 2x4...the architects and designers are getting it!!!REJOICE!!!but i make them pay for the 3"build,,,with proper education you can save them $$$ and sell the 2.5" lift and still give them the performance they need...(seems i remember 2.5" being the "sweet spot" for the consumer,,but i imagine that is changing to our advantage as the prices of operating our structures continue to rise...again,,REJOICE!!!)
so,,yes,,,i "sell" a 2 3/4" (+/- 1/4") in either a 2x4 or a 2x6 cavity for an r-19 nominal,,,and i err to the side of the consumer in the 2x6 application,,,(hold on the phones ringin,,,get it??)...and i will deeply discount the 4th inch just to get the added performance,,,those folks will luv our product and tell everyone about you....particularly when it is REAL hot or REAL cold and every one else is bitchin...
i hope this helps,,,have a great weekend and take some time to hug your babies...
'dude ;)

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