SPF and condensation | Insulation/Energy/Building Envelope Q&A | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Author	Comments
Jeff Knight Posted: Mar 03, 2010 02:49 PM	SPF and condensation I'm building ultra townhomes w/ stone roof terraces over the master bedrooms, in Zone 4 (Wash DC). The roofdeck / ceiling construction is 2" stone on 4" concrete on metal pan decking over 8" steel i-beams, then 1-3" under the beams to the drywall surface (roof deck slopes). So between the beams we have 9-11" for insulation. We want to spray closed cell on bottom of pan decking, and to encapsulate the beams. 3" has been recommended by our contractor, that's what he typically does in our area. That's roughly R-16, and my building code says I need R-38. If we batt R-22 fiberglass under the ccSPF, we lower the dew point on the surface of the cc to where we get condensation. Remove the batts, no condensation, but also no R-38. Has anybody else faced this dilemma?
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: Mar 03, 2010 03:10 PM	Welcome to the world of Spray Foam and the R-value dilemma! The codes are based on fiberglass R-values and not R-values of other products. Techincally speaking, R-value should only be usedon solid materials and not porous materials like fiberglass. That's where the lobbyingh of the filterglass comes into play. Because they are the big gorilla in the industry, they rule out! So, How can you meet an R-38 code when it's beasedon filterglass performance R-value?? This just shows the need of the SPFA and other industry players to establish a different I-Value or something which takes into consideration the Conduction, Convection, and Radiant Heat transfer under real life circumstances! So, Techincally speaking your R-16 will work fine for the codes unless you have a code person who wants to push his weight around?? Then you're stuck with pushing him around in front of the code!
Posted: Mar 03, 2010 07:59 PM	Who do we need to get on and where do we need to go to change this? Many of us are members of SPFA, just because what I spray isn't pink doesn't mean that we can't change things.
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: Mar 04, 2010 09:49 AM	Agreed! There was a meeting towards the end of the SPFA conference that had feedback from all of us contractors on the good and bad; the likes and dislikes. This was one of the major points of contention that we all agreed needed to be changed! Now, comes the real question: How do you change it whenthe filterglass guys are beating down every idea we come up with. It's been going on for many years now and it's time it has stopped! So, where do we go from here? Good question? Many people suggested getting reallife data and using this to combat the codes. I'm not sure this will work with may of the code officials out there and their tendancy to only look at the code verbiage. They ignore common sense data which is what we're talking about! So, what data do you have to support less is actualy more? Let's get the data out here and start discussing the issues!
Tim Wojnarski Posted: Mar 04, 2010 10:00 AM	JK59, Send me an e-mail, I might be able to help. timwoj@verizon.net.
Jeff Knight Posted: Mar 04, 2010 10:17 AM	Jim, were you saying in your previous post that 3" of ccSPF is as good as 12" of fiberglass batt (R-38)? That seemed to be what my contractor was saying, though he didn't have any way to back it up, other than to say 'this is what we do in this area.' I called my county plan reviewer. He said he was aware of the arguement between you guys and the fiberglass guys. He said understood your position and agreed in theory, but the county's position was to stay out of it and enforce the codes as they are currently written. I'd love to help you guys out, but I need somebody to say that 3 or 4" of ccSPF (my contractor is proposing ComfortFoam at R-5.6 per inch) really IS as good at keeping the heat in as R-38 of fiberglass.
Terry Adams Posted: Mar 04, 2010 12:00 PM	http://www.coastepa.com/canewhomes.aspx This is a link to our electric cooperative here their comfort advantage home requirements is R38 attic insulation or R-20 Cathedralized Unvented Attic Insulation (Encapsulated Attic) - foam insulation between roof rafters on under side of roof decking and on attic sidewalls and gable ends. This is the only document I have ever found that reconizes foam as twice as effective as glass. They are a member of Touchstone Energy Cooperatives which is nation wide, you might check touchstone's web site for your area.
Posted: Mar 05, 2010 05:31 AM	...you can,,for a fee,, get some independent testing done.. called the "performance path".. this will indeed show that spf applied at 1/2 the rvalue of filterglass will perform at equal performance...it is important to recognize "equal performance",,you cant promise reduced energy useage with this app,,, but equal thermal performance,, you cant have steak on a hamburger budget.. we recently applied to the local habitat for humanity home with a GW 052 app to 5-6" in the lid...@ R4.2/inch,,you end up with a Rvalue of about R21-25 depending where you stick the probe...this home has had the performance path evaluation and meets our local energy audit just fine... you can also,,for a fee,,,get some "comparative" performance path calculations,,,useing the same print,,,but different insulation materials,,or hvac,,or whatever "analysis" you are trying to look at.. you can not apply 50% less insulation material and promise 30-40% increased thermal performance..physics is fizcics... 'dude
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: Mar 07, 2010 02:03 PM	So, you think we can get something passed the codes people that wasn't intended? Well, That seems to be exactly what they've done! They've applied a R-value test to a non-solid material - fiberglass! But wait, it gets better, because they've based the codes on this filterglass R-value and based on it's performance. Now the filterglass manufacturers want us to believe that MORE is BETTER, but what should we really believe? So, there's a big issue here with what has been done and what shoudl be done! So, Does filterglass act as an air barrier? No! Does that mean it's bad? No, but it does lead to the question, "What is an air barrier?". Foam! Roger Morrison did a study back in 2006 which addressed this exact issue? http://www.biogreen.us/images/pdf/determining_insulation_thickness_by_roger_morrison.pdf Enjoy!

Author

Comments

Jeff Knight

Posted: Mar 03, 2010 02:49 PM

SPF and condensation

I'm building ultra townhomes w/ stone roof terraces over the master bedrooms, in Zone 4 (Wash DC). The roofdeck / ceiling construction is 2" stone on 4" concrete on metal pan decking over 8" steel i-beams, then 1-3" under the beams to the drywall surface (roof deck slopes). So between the beams we have 9-11" for insulation. We want to spray closed cell on bottom of pan decking, and to encapsulate the beams. 3" has been recommended by our contractor, that's what he typically does in our area. That's roughly R-16, and my building code says I need R-38. If we batt R-22 fiberglass under the ccSPF, we lower the dew point on the surface of the cc to where we get condensation. Remove the batts, no condensation, but also no R-38. Has anybody else faced this dilemma?

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: Mar 03, 2010 03:10 PM

Welcome to the world of Spray Foam and the R-value dilemma! The codes are based on fiberglass R-values and not R-values of other products. Techincally speaking, R-value should only be usedon solid materials and not porous materials like fiberglass. That's where the lobbyingh of the filterglass comes into play. Because they are the big gorilla in the industry, they rule out! So, How can you meet an R-38 code when it's beasedon filterglass performance R-value??

This just shows the need of the SPFA and other industry players to establish a different I-Value or something which takes into consideration the Conduction, Convection, and Radiant Heat transfer under real life circumstances! So, Techincally speaking your R-16 will work fine for the codes unless you have a code person who wants to push his weight around?? Then you're stuck with pushing him around in front of the code!

Posted: Mar 03, 2010 07:59 PM

Who do we need to get on and where do we need to go to change this?

Many of us are members of SPFA, just because what I spray isn't pink doesn't mean that we can't change things.

jimcoler

I've expanded my knowledge into t

Posted: Mar 04, 2010 09:49 AM

Agreed! There was a meeting towards the end of the SPFA conference that had feedback from all of us contractors on the good and bad; the likes and dislikes. This was one of the major points of contention that we all agreed needed to be changed! Now, comes the real question: How do you change it whenthe filterglass guys are beating down every idea we come up with. It's been going on for many years now and it's time it has stopped!

So, where do we go from here? Good question? Many people suggested getting reallife data and using this to combat the codes. I'm not sure this will work with may of the code officials out there and their tendancy to only look at the code verbiage. They ignore common sense data which is what we're talking about!

So, what data do you have to support less is actualy more? Let's get the data out here and start discussing the issues!

Tim Wojnarski

Posted: Mar 04, 2010 10:00 AM

JK59,

Send me an e-mail, I might be able to help.

timwoj@verizon.net.

Jeff Knight

Posted: Mar 04, 2010 10:17 AM

Jim, were you saying in your previous post that 3" of ccSPF is as good as 12" of fiberglass batt (R-38)? That seemed to be what my contractor was saying, though he didn't have any way to back it up, other than to say 'this is what we do in this area.' I called my county plan reviewer. He said he was aware of the arguement between you guys and the fiberglass guys. He said understood your position and agreed in theory, but the county's position was to stay out of it and enforce the codes as they are currently written. I'd love to help you guys out, but I need somebody to say that 3 or 4" of ccSPF (my contractor is proposing ComfortFoam at R-5.6 per inch) really IS as good at keeping the heat in as R-38 of fiberglass.

Terry Adams

Posted: Mar 04, 2010 12:00 PM

http://www.coastepa.com/canewhomes.aspx
This is a link to our electric cooperative here their comfort advantage home requirements is R38 attic insulation or R-20 Cathedralized Unvented Attic Insulation (Encapsulated Attic) - foam insulation between roof rafters on under side of roof decking and on attic sidewalls and gable ends. This is the only document I have ever found that reconizes foam as twice as effective as glass. They are a member of Touchstone Energy Cooperatives which is nation wide, you might check touchstone's web site for your area.

Posted: Mar 05, 2010 05:31 AM

...you can,,for a fee,,
get some independent testing done..
called the "performance path"..
this will indeed show that spf applied at
1/2 the rvalue of filterglass will perform
at equal performance...it is important
to recognize "equal performance",,you cant
promise reduced energy useage with this app,,,
but equal thermal performance,,
you cant have steak on a hamburger budget..

we recently applied to the local habitat for humanity home with a GW 052 app to 5-6" in the lid...@ R4.2/inch,,you end up with a Rvalue of about R21-25 depending where you stick the probe...this home has had the performance path evaluation and meets our local energy audit just fine...

you can also,,for a fee,,,get some "comparative" performance path calculations,,,useing the same print,,,but different insulation materials,,or hvac,,or whatever "analysis" you are trying to look at..

you can not apply 50% less insulation material and promise 30-40% increased thermal performance..physics is fizcics...
'dude

jimcoler

I've expanded my knowledge into t

Posted: Mar 07, 2010 02:03 PM

So, you think we can get something passed the codes people that wasn't intended? Well, That seems to be exactly what they've done! They've applied a R-value test to a non-solid material - fiberglass! But wait, it gets better, because they've based the codes on this filterglass R-value and based on it's performance. Now the filterglass manufacturers want us to believe that MORE is BETTER, but what should we really believe?

So, there's a big issue here with what has been done and what shoudl be done! So, Does filterglass act as an air barrier? No! Does that mean it's bad? No, but it does lead to the question, "What is an air barrier?". Foam!

Roger Morrison did a study back in 2006 which addressed this exact issue?

http://www.biogreen.us/images/pdf/determining_insulation_thickness_by_roger_morrison.pdf
Enjoy!

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