Slow cure foam injected behind fiberglass in walls?

Has anyone heard of injecting slow rise closed-cell polyurethane foam (such as Foamo's HandiFLOW) into wall cavities behind existing fiberglass batts?  or injecting it into empty rafter bays? I have heard of a proposal to do that, and I am very skeptical that it would work effectively.

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Here's all three MSDS for InsulSmart MH.




Brad, I don't know about this cc product, but I have had very good results with Icynene's oc injected into a series of 3/4" holes. I will choose cellulose if the application allows it, but there are some houses that foam is the best or only option.  We have only used this product twice, but both times I have been impressed with the ease of installation(including prep and cleanup) and the thermal performance achieved. It did not pop any drywall or have any other negative effect besides a strange popping sound reported by the tenants as it cured overnight.

In one home, this product really saved the day. A double rammed earth wall with a 5" hollow cavity in between. This house was 150 years old and the outer wall was starting to fail from a long neglected roof leak. The foam did not crack the wall further and turned the assembly into a rammed earth sip.

Slow cure foam could be urethane, either closed cell or open cell, or something like the product Bob Sullivan is suggesting.  I have known Bob for a long time, and he has a tendency to take the more difficult path.  He usually does a lot of research first though. 


I am skeptical of Insulsmart too.  I am not endorsing anything here, but I am interested in hearing Bob out, and I thank him for the posts here. 


I can tell you I am familiar with Bob's work at ICAA ( and he is not making up his involvement there.  At the time, he likely had some support or collaboration from people like Ron Graves, Oak Ridge Nat. Labs, and several different manufacturers. 


Cellulose is simple, readily available, very safe, non harmful to the environment, and cheap.  about the only problem is some has ammonia sulfate as fire retardant in too high a quantity and that material can off gas ammonia and destroy metals if it is exposed to water.  This can be completely avoided by specifying all borate cellulose.  In walls, require 2.5+ ft density and settling is defeated. 


if Insulsmart is going to survive in the market it has to prove performance to justify price.  it also has to show profitablility to contractors. 


Bob, in your posts here, I saw you ship it dry.  is there some reccomendation for PH of water to mix it?  is thre some shelf life for the liquid form?  will the resin harden in the lines if it sits too long?  what is he shelf life in the lines? if it has to be flushed, what are disposal guidelines for the resin only?   

Pat, I'll answer your questions one by one, as follows:


Is there some recommendation for PH of water to mix it?  As near neutral pH as possible.


Is there some shelf life for the liquid form?  The shelf-life of mixed (liquid) resin component is 30 days. The foaming catalyst ships as a liquid concentrate with a one year shelf-life. The shelf-life of powder resin is one year.


Will the resin harden in the lines if it sits too long?  Yes. Mixed resin hardens can harden in the lines of idle rigs, say over a weekend. We recommend cleaning the lines at the end of each work day. If hardening includes freezing, installers are trained protect equipment and foam components to facilitate cold weather applications.


What is the shelf life in the lines? Shelf-life varies as a function of trace elements that may be in the water. Installer training and experience enables making adjustments to preclude water problems.


If it has to be flushed, what are disposal guidelines for the resin only?   Purge the lines and clean the nozzle, lines and valves when work ends each day using warm water. The resin and scrap foam do not require special disposal guidelines. Because they are biodegradable, an option is on-site disposal. Aminoplast foam is used worldwide to amend athletic turf substrates e.g.Athens and Bejing Olympics athletic fields and for a host of horticultural applications e.g. green roofs and greenhouses etc. We do not participate in that industry segment which is led by a Dutch company. Note the attached photos.


The Tripolymer wall foam insulation that I have used would be a good fit for this application.   It is a phenolic-resin base that goes in like shaving cream.  There are no issues with toxicity.  It does expand upon installation - it can push out walls a little if the installers are not careful.  There is some shrinkage, but that is minimized if it is a retrofit around existing insulation.  R values are over 6 per inch and its air sealing properties far exceed "dense-packed" cellulose.  If it oozes in somewhere, its an easy clean-up.



John, InsulSmart and Tripolymer 105 install similarly. Current and past Tripolymer 105 brochures disclose R-4.8/inch @ 75 F mean temperature consistent with FTC Rule 460. Also disclosed is that Tripolymer 105 does not expand after it exits the nozzle consistent with our understanding of how injection foams perform. In a previous reply, we disclosed that cavity insulation has little to do with abating air-infiltration into framed structures. About 80% of the infiltration occurs through framing joints and penetrations. Thus, all cavity insulating systems and materials (dense-pack, FG batts, foams etc.) perform better in conjunction with well executed strategirs for caulking and sealing joints and penetrations with suitable materials. The joint between the deck and sole plate of wood framed exterior walls typically accounts for 25% of total air-infiltration into residential structures. Sealing HVAC ducts and electrical outlets & recepticals etc. is essential, too.



Thanks for the correction on R-value and we certainly agree on where to attack air sealing first.  At colder temps, Tripolymer's R value goes up.  Am I right that the R value for fiberglass goes down at lower temps?


The expansion does happen at the nozzle, but there is enough force with the equipment to pop drywall, or even trim, if the installer is too agressive.


While cavities are not the first step, I have seen individual cases where wall cavity retrofits (cellulose or foam) have made significant infiltration reductions - the foam seems to have a greater impact.  I'd support its use in this case because it can be installed by drill and fill to correct poor installations.








A nice thing about injection foams is that they more easily flow around pipes, wires and protuding nails etc. Fiberous insulation sometimes hangs up enough to block the flow of insulation into a cavity; thus, creating a void beyond the blockage. Don't get me wrong, injected foam does block air flowing through penetration holes. However, overall, the majority of air infiltrates through framing joints.



Across the insulation industry, most manufacturers disclose R-values at 75 F mean temperature except for injection foam manufacturers. Our industry has traditionally disclosed at 25 F or 32 F or 35 F probably because the numbers are bigger. Our company discloses for InsulSmart at 75 F because InsulSmart is primarily a "residential" insulation product and FTC Rule 460 - The Home Insulation Rule - mandates disclosure at 75 F mean temperature.


As to whether fiberglass losses R-valus at low temperatures, the answer is a qualified "yes." If temperatures drop for very short periods at a time, the overall impact is neglible. However, during sustained periods of low temperature convective air flow does work to reduce the effectiveness of low density fiberglass insulation. High density fiberglass is less suseptable to convection losses. Again, a well executed air infiltration strategy reduces the potential for convection to become established in cavities insulated with fiberglass. Foam insulation is not suseptable to to convection losses.

I feel the fiberglass insulation will be condensed rendering it largely ineffective.  The spray foam is an excellent insulator however.  What climate do you live in?  Why do you not feel that it will work effectively?

Whatever R-value loss occur due to fiberglass compression is partially offset by an R/inch gain due to the increased density of the fiberglass e.g. 3.5" batts are labeled R-11, R-13 or R-15 depending upon their respective densities. The k/density relationships for both loose-fill and batt type fiberglass insulations are well  How much the fiberglass compresses depends largely upon its initial density. The "compressed" fiberglass' R-value combined with the injected foam's R-value generally provides for significant improvement. We're on the same page. I do think (know) it's effective. I live in Virginia's mixed humid climate (IECC Climate Zone 4), and  have worked in all of the climate zones except Alaska's over the past 46 years.


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