I saw a house yesterday with a foamed roof deck.  While talking to the HO and his wife, she got the invoice and the recommendation out.  It recommended taking the old insulation out and the spraying 4 inches of foam.

If you take the old out, why foam the roof deck?  Why not foam the attic side of the ceiling?

Why only 4 inches?

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George, the only catch with Open Cell is it still hasn't been tested or approved to meet codes. (If someone has actual test results & not a salesmen saying we do it all the time, then I might try it)

They may require you to spray on a vapor barrier which will then allow the foam to act as one huge spounge instead of limiting the damage to a small area of the roof incase it gets damaged

As for how hot attics get, in the southern climates - attics can easily get into the 140 to 180 mark during the spring to summer time & sometimes even higher than that

John,  I have run into these houses as well.  Usually over 5000 sf with only 2-3 people living there!  I have 2 issues with this type of system. 

1-Insulated roofs in an attic?  Doesn't that increase the volume of area that needs heating & cooling?  Is that efficient? Have to agree with you and ask why put the attic within the envelope?

2-Spray foam... I realize this is an 'energy" group but we should be "pros" too, & considering the green and sustainability factors as well.  Arguably spray foam is neither..


Hi Kent, and thanks for the comments. (By the way - does anyone here really consider a 5000 SF House Green?)


For #1 - the answer is no on increased cooling & in some cases it decreases the amount. Let me point you to one of my blog articles on "hot-roofs", and also encourage you to read the comment below it by David Butler. http://blog.sls-construction.com/2011/what-is-a-hot-roof


As for #2 - well you can argue that, but many of us would say you are wrong on quite a few fronts and be able to prove it with facts & not just probabilities or "potential" (GWP) - to some extent it gets down to what you consider is green & sustainable.

No Sean, it doesn't matter what people 'think' is green and sustainable, you argue it isn't you are simply uninformed, or a poser.  


A poser is a person more interested in appearance than performance.  Posers are likely to put solar panels on their roof and not weatherize.   After all, their homes need to breathe.


Resource cost means spray foam is green. 




We are talking about improving homes.  If a homeowner thinks something is green and/or sustainable they might proceed with the improvements.  If a homeowner thinks your recommendation is not green or sustainable they probably will not proceed.  This assumes that the homeowner values the green / sustainable issues.  In my experience, most home owners like being green after they find out they are saving money, will be more comfortable or get something they want, like an old furnace replaced.


If we aren't talking about helping people to improve the energy usage in their home, then what is the subject?

Uh wow Ted - this is a place to discuss best practices & argue them on their merits - not for personal attacks which are so far off the mark as not even worthy of responding to. As for your "points"...

Seeing you know exactly what is green & sustainable, you might want to post it as everyone (including organizations) seemingly have a slightly different take - I think plenty of us would love to have that perfect definition (besides its a color & marketing term)

I know plenty of individuals will argue against your belief that foam is green based on GWP, cost, sustainability... If you had bothered even looking at the article I posted which helped to answer both John's original question & Kent's reply - you would know that not only do I support foam, but I also install it when warranted, it is in the budget, and it is the best product for the job.

Now as for a complete side point - there is no such thing as green product. A product can be manufactured in a green manner but if it is installed improperly, not maintained, etc... it is nothing more than a waste

John, I agree; comfort, $, then maybe green as icing.

Sean, Kents comment shows a common path we all must go down, and his position that foam is not green or sustainable shows he hasn't proceeded very far down that path, yet is prepared to take strong inflexible looking positions. I felt your resonse to his comment about foam not being green didn't quite go far enough.

People seem to think products we use for energy efficiency should be what, edible? That path is laden with hypocracy, and inefficiency. It reminds me of people with access to natural gas who install ground source, then have no money left to weatherize their inefficient homes.

That type of green is without substance, self congratulatory showing off to the neighbors, not doing what has real effect upon reducing footprint. Theyve shifted load, not reduced it. Green in home performance is allocating limited resources to where they have greatest energy dependence reduction. Installing improvements that will have the greatest energy $avings benefit, allowing $ resources to replenish as quickly as possible so future projects may be undertaken. Projects that don't $ave delay or remove feasibility of future projects.

As you and I know, that very often means spray foam, even though it's not edible.

Ted - you are making some pretty broad judgements based on very little information....

Inflexible looking?  How did you come to that conclusion?  Have we met?   "his position"?...  It was put out there  as a debateable comment or question - not a position...

As for your statement about what green is... I'd disagree about most of it.  Green shouldn't be focused on future projects nor focused entirely on energy usage... it is simply better building practices encompassing all the aspects of a project.  If the future projects are the focus then it is likely the present project is going to suffer...


Sean- Great feed back!  Your blog was very pertinent.  I would have to agree with you about Davids comment the terminology is good, however, it still doesn't really address the fact that the attic space will require more energy to heat/cool or cool it than if the thermal barrier is at the ceiling  The answer may just boil down to which benefits or trade offs does the customer want....   

I'm sorry Kent, it appeared more a position than a question:

but we should be "pros" too, & considering the green andsustainability factors as well.  Arguably spray foam is neither..

I could be completely misreading, but that seems more an enticement to argue than discuss.  More the position of someone with an axe to grind than someone interested in expanding their knowledge.  It appeared to be coming from someone with out water wings venturing into very deep water.  


Your mis-read of my comment on cost-effective decision-making is either argumentative or uneducated as well.  While you may view energy efficiency measures as a single project, I view it as a path.   


Design needs to be tailored not simply to the building needs, but to the occupant needs and risk tolerance.  Some people dip their toes in and when successful, begin to wade.   Some jump in to their waste, and some dive in.  Understanding the complex interconnections between their level of education and experience in this area and their financial situation if successful can create lifelong momentum toward environmentally friendly choices, if unsuccessful it can kill it dead.  If we want green initiatives to experience viral growth we need to generate positive momentum anywhere we can.  No matter how "green" that initial effort is it is the momentum that matters. 


If I've misread your intentions behind your words, please accept my apologies. 





Kent - it was my pleasure, and I forgot you had left a comment there also - so seeing this is still a sticky point, think delta T and how heat transfers - would you rather fight 95 degrees of heat or a 140 if your house is at 80? So even though you have more space, the difference in Delta T's is huge. The best thing to do is to plug the numbers into a program like RemRate or Design and see what the numbers come out to be - I think you will be surprised.

Tedd - I am glad to see the apology for Kent, but let me just add a little bit of advice - no one is here to argue or pick fights, we are here to help improve either our skills, knowledge &/or customers lives by discussing the issues on their merits. Calling people names, etc... won't convince anyone of anything & no matter what, you will never convince everyone - sometimes it is best to just let them work through it or not add any comment juice to a thread.   

While you may disagree strongly on green meaning different things to different folks, you may wish to open your mind up to all the different views as it will not only help you grow, but improve your bottom line and customers lives. All in all, we are all looking at helping others improve their homes, lives &/or the environment & I can't fault anyone for that - now as for how they get there, well...

Now if you want to raise your blood pressure a little - http://www.remodeling.hw.net/building-performance/the-folly-of-deep... (be nice)



Looks like we might need a new discussion topic just to cover,

Now if you want to raise your blood pressure a little - http://www.remodeling.hw.net/building-performance/the-folly-of-deep... (be nice)



I just read the article and I totally agree. The things he is pointing out are exactly the problems I see here in Utah. If we are going to help homeowners to reduce their utility bills, we must be responsible for any unintended consequences of our actions.

I think the point is this; if you are going to test only, it is OK to just know how to test, but if you are going to recommend or install upgrades, you should have a very broad understanding of every system that could possibly be affected by those "upgrades".

I get a lot of my technical knowledge from http://www.buildingscience.com/


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