The context:  I am from a northern climate municipal electric/natural gas utility.  We provide rebates to customers for various energy efficiency projects, including adding insulation to existing homes.


The issue:  We've had a few issues with the application of injection foam (spray foam applied directly into closed wall cavities of existing homes).  I've attached a few pictures from a customer that removed their drywall about 3 weeks after the insulation was installed (because the area still felt very cold to him, for obvious reasons). The last picture is a "test" cavity one of our engineers rigged up, to mimic some of his existing wall cavities (he removed the drywall covering this portion after 1 week's time).  We have some IR images that I didn't attach here, but reveal similar results.

Inspections of several other homes revealed similar results as well.  This is typically very expensive insulation in my service territory.  


My questions:

1) Does anyone else know if there are any utilities that have banned injection foam insulation projects from their rebate programs for sidewall or basement/foundation insulation?  

2) Does anyone recommend any basic ground rules for utility rebate programs that do fund injection foam insulation projects?  One basic rule we have at this time is to not fund residential injection foam of concrete block basements (i.e., funding the injection of this foam insulation into hollow cores of cement block walls in a residential basements).


Other utilities in my area do not seem to have policies or opinions about this issue, but do allow this type of insulation in their rebate programs.

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I don't have any answers to your questions, but thanks for sharing those photos--they are sobering. It seems at minimum you would require IR verification of the completed job before releasing funds. I am monitoring one injection foam project underway and it seems to be going well, but they do have trouble getting foam into a few places, and lacking their own IR imager they don't even know it. From my reading, injection foam is not widely used anywhere, and I don't doubt that the skilled installers are rare.
Erin, I am having the same struggle myself right now. I have been rebating these installations, but I am also planning to do some "after" thermography to try to get a handle on how well they are doing the install.  Like everything else, it comes down to the quality of the installation and the product.  I think if their product is properly mixed and properly installed, it is effective.  However, if either is off just a bit, the total R value needs to be discounted.

These photos show the importance of having insulation installed by expirenced and trained professionals. Unfilled cavities are the result of improper installation. I've seen cavity voids with all types of insulation.

When filling cavities blind,  with any material, experience is key.

Andrew - I agree with your comment 100%.  However, you neglected to point out the apparent shrinkage that has occurred.  You can tell from the shape the foam had taken at some point after the installation and prior to removal of the drywall - 90 degree angles & flat edges caused by the foam being pushed against the framing.  In many areas, those edges are now several inches from the framing.  If this was indeed caused by shrinking material, the best installer in the world wouldn't have been able to install the product in a way that would provide acceptable performance.  Wouldn't you agree?


You can go to the web page of the manufacturer of this product and download the architectural specification sheet that states"Shrinkage: 2% maximum."  Obviously, the shrinkage in the photos greatly exceeds 2%.  I would assume that this 2% maximum shrinkage claim is based on the product being mixed and installed exactly to manufacturer's specs.  That begs the question - how hard is it to mix and install the product to the manufacturer's specs AND if a really good contractor follows those instructions to the letter, can he still expect between 0% and 2% shrinkage?


If the average stud cavity is 15.25" wide and 93" tall or 1418.25 square inches.  If the insulation shrank 2%, there would be a 28.37 square inch gap in each cavity!


David & Curtis - I'm all in favor of third party, independent verification; and common sense would suggest that thermal imaging gives us an idea of whats going on inside the wall, but as you both know, two people can look at images from the same location and arrive at completely different conclusions.  The other thing we should consider is that there are lots of thermal cameras out there, but far fewer certifications and training hours to go along with them.  On top of that, how would one accurately verify cavity fill jobs completed in the mild months when delta t is very low?  Even wall cavities like the ones pictured above could appear to be well insulated under those conditions.


If I were the steward of ratepayer money, i.e. utility incentives, I would be disinclined to offer a rebate for this material without evidence that it is performing as advertised, not only after installation, but for an extended period of time.  Unfortunately, I'm not sure a procedure exists that could guarantee such results.  It may boil down to conducting long-term studies based on actual consumption reductions as the result of installing the product.



We agree with your last sentence in this post above and have been looking into this. A couple of months ago, our utility has banned this product from our list of products eligible for utility incentives. 


Erin Buchanan


 No, I do not agree. The applicator has complete controll over the manufacturing of the foam . If the mix is off, if the resin is old, If the ratios are off,  the foam may appear good and ready for application. But is the weight right? Is the gel time correct?  If not shrinking out of specs. occurs. Hence the need for experienced and trained contractors and aplicators.

The argument is with the self-assured, untrained applicator who believe, that if one cannot see it, it must be ok. Checks have to be adhered to when pumping foam-in-place.

When appllied correctly there is no better, more efficent, cost effective way to insulate the closed cavities. 2% or not.  (The application can always be applied in multiple lifts )

Proof is in the pudding.



I agree training is very important and is no substitute for experience.  Unfortunately, the installer of the foam from the photographs has multiple crews throughout the State of Iowa and would appear to be installing a lot of this product.  Since your explanation for the poor performance of the product shown in the photos is not inherently product failure but is because the installer is untrained, how can we eliminate these untrained installers from screwing up jobs all over the State?  Don't the manufacturers of this product provide and/or encourage installer training?  If so, what happened?


Also, what sort of "checks" have to be adhered to when pumping foam into closed cavities?  I'm assuming you're referring to some sort of self-applied quality control during install?  Could you explain the procedure?


You said, "When appllied correctly there is no better, more efficent, cost effective way to insulate the closed cavities. 2% or not.  (The application can always be applied in multiple lifts )

Proof is in the pudding."


Even after 2% shrinkage it is the best product out there?  If the proof is in the pudding, I'd appreciate it if you could send the data or tell me where I could find it, I would be happy to review it.


If an insulation contractor came to my house and told me that his product would probably shrink up to 2% but that it was the best, most efficient, most cost-effective way to insulate closed cavities I don't think I could keep a straight face.  I would probably knock him down on my way out the door to quickly call one of his competitors!  Unfortunately, my guess is that those who sell the product don't bother to mention the shrinkage during their sales pitch.  It's certainly not in their full-page newspaper ads or radio commercials here in Iowa.


Recently, I've been involved in two projects in which the homeowners obtained bids for both dense packed cellulose and injectable foam.  The cellulose bids came from a contractor with over 30 years of experience and a good reputation.  In both cases, the cellulose bids were approximately half the cost of the injectable foam - as much as $3500 difference.  Is this typical?  If so, it would be difficult to say the foam product is the most cost-effective.  Even if we were to assume the product does exactly what the marketers say it will do (of which I am skeptical), it would take a long time to pay for a 100% incremental cost increase.  In order to receive a 10% return on investment for the incremental cost increase, the product would have to save $350 / year MORE than what the cellulose would save.  Do you think this is attainable with an injectable foam?


Finally, aren't the injectable foams of today direct descendants of the urea-formaldehyde foams of the 70's & 80's?  Much of that foam is in powder form laying in the bottom of what are now mostly empty wall cavities.  I guess I would much rather have 2% shrinkage than powder at the bottom of my wall cavities - have they addressed these durability / longevity issues?



The particular insulation I refer to in this discussion is a "dry urea-formaldehyde powder resin", which is a dry powder that is mixed on-site with water immediately prior to installation. So it's not exactly the same as the stuff from the 70's, which were liquid formaldehyde substances, which led to off-gassing, etc....


However, there are other injectable foams to do not involve powder.  In my utility's service territory, we also have an injectable foam provider who uses a different product - a phenolic foam.  This is not a powder that is mixed on-site, but a foam that comes ready to install.  It is somewhat different from the powder resin.  So not all injectable foams are the same.

The sky does not fall because foam is used for insulation.

In the dynamic world foams hold their insulation value better than fibers. As humidity fluxuates so does the r-value of cellulose and fiberglass. ( I wonder if salesmen tell this story?)

All types of insulation have their own attributes. And the balance of these should be weighed for each application. As manufacturers progress, all building  materials become new and improved. Yet, nothing will ever become perfect.






Andrew - First, I noticed you provided none of the following:

1.  Do the manufacturers provide installer training

2.  Procedure/s for the "checks that have to be adhered to when pumping foam in place"

3.  The pudding, i.e., any credible study or data that has been compiled that prove this product saves the amount of energy the marketers advertise

4.  Whether a 100% incremental price increase over dense packed cellulose is typical, at least from your experience or in your marketplace


Second, I'd like to clarify what I'm after here - Will the product do what it has been advertised that it can do with the following items in mind:

1.  According to a manufacturer of this product, maximum shrinkage is 2% (I've assumed that this 2% shrinkage claim is based on material that has been installed to specs - if you know differently, please advise)

2.  Can the product be installed, on a reasonably repeatable basis, to manufacturer's specs, and is there an effective way of verifying it, either during or after installation.

3.  Injected foams, of the same or similar type installed in the 70's & 80's had significant longevity & durability issues - is it possible this product could have the same or similar issues?


These seem to be simple requests; and if the product is as good as the marketing, I would imagine the proof exists.  If not, then I think it's safe to say there are more cost-effective choices that have more successful track records.  Again, based on what I've seen in the photos, my experience with local installers, and the general lack of evidence that the product will be in service long enough to pay for the customer's investment, I would be disinclined to offer an incentive for the installation of this material.


This whole discussion brings up an important tool that many of us in the utility incentive world are missing: third-party verification. So often due to lack of time or knowledge, we accept a manufacturers claims as fact and move on. And it is difficult to pick winners and losers because no one wants to get sued.

In the end, my top concern (as is any utility rebate program) is what's best for the customer. It is difficult to see the enthusiasm with which a customer writes a $3500 check for something that will maybe perform half as well as its advertised when you can easily identify other measures they could take that would save more energy at less cost.

I agree with your third-party verifier comment.  However - who is that?  There is an IR shot included in a comment posted on 3/1 about foam - see above.  I can think of a couple of different interpretations for each of the hot spots that show from the exterior - how do we know it was the fault of the foam and that dense-pack cellulose (or the new fiberglasses) would not have resulted in the same problem?   There are a whole lot of auditors who will be vying for this work, and how many have looked at more a couple of dozen houses?  

Ed Minch


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