Any recent experience with “RetroFoam”?
Anyone have experience with recently applied UFFI foam?? I found an old article here about the re-emergence of UFFIs. To find it search here for UFFI to find a 2013 article by Alex Wilson. There is a company he lists, RetroFoam with outlets nationwide. I came across them while looking for injectable urethane foam, local applicators of which I could not find. The sales guy I talked with told me as we were getting into details that the foam is “engineered” to shrink about 1% which leaves voids around the edges so that your house does not end up being too tight. That was a red flag for me as my main reason for considering it is to fill rafter cavities under a roof that has new shingles over a synthetic impermeable underlayment. He also told me they did not need to pull a permit for “just insulation”. That made me more wary. Cost to do the entire second floor with sloping ceilings in our 1-1/2 story Victorian was bid at <$5K for the RetroFoam. Contrast that to more than $20K by the time for flash and batt when we are all done demoing, spraying, furring, and drywalling. So it’s compelling to consider this phoenix from the ashes UFFI. I have heard about folks who have used dense pack though with my rough sawn 2×4 rafters I’d get cavity R values of 15. I’d like to do better than that, still, I hate lugging plaster and all the $$$$. Thanks for any thoughts on this.
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A lot of stuff on their R-value page is simply wrong, which is not uncommon for foam companies. What climate zone are you in? Open-cell foam is not a good choice for roofs in cold climates. I would opt for cellulose in a situation like this; its R-value is lower but it can store and redistribute moisture, and protects everything it touches from rot (to a degree, anyway). Open-cell foam allows moisture to migrate to the roof sheathing where it gets stuck and can result in rot.
You don't want "voids around the edges" and a house cannot be "too tight". All those voids are doing is wiping out one of the big advantages spray foam has, which is the ability to air seal well. I know this isn't quite the same material as spray foam, but it's very similar -- just without the "spraying" part. Most of the questionable claims made by spray foam companies are based on the ability of the product to air seal so well, and my guess is this company you're looking at is doing the same thing but also stating that their product is intentionally leaky. That's a strange way to approach things.
This type of material is also likely to gunk up all your electrical boxes so be wary of that.
I completely agree with Michael about this being a risky product to use in a roof assembly. The only really safe way to do an unvented roof is either continuous insulation above the sheathing (think polyiso on top of the roof), or closed cell spray foam directly against the underside of the roof sheathing.
Note that insulation projects that don't change the structure are often done without permits as a "maintenance" type of project. If you have any questions as to how your local municipality views this sort of project, just give their building department people a call and ask.
Bill
Bill, just now saw your comment. Thank you. Michael's came in first so my reply to him is a bit out of order. I'd be curious to know what you think of the approach described in the article I provide a link to below re low carbon approach. I also stumbled on this older Martin Halliday article re hygric redistribution and it all has me head scratching again. https://www.greenbuildingadvisor.com/article/hygric-buffering-and-hygric-redistribution Thanks! -Dale
Hi Michael,
We are in Marine 4C. I know IRC at least says we should be worried about condensation. And it does get down below freezing intermittently in Winter, and sometimes much colder for perhaps a few days into the teens. I looked at Retrofoam's tech facts sheet and immediately notice that they claim a better whole assembly R value of 20 when the foam itself is supposedly 15.7 in a modern 2 x 4 wall. That's bogus. And why spec R value at 25F? Allison Bailes in his book "A house needs to breath, or does it" taught me that a wall (or ceiling) assembly absent any thermal break have a much lower total R value due to bridging of the framing. We've got old rough sawn 2 x 4s on 12" centers so that's a lot of bridging. So last night I was gritting my teeth and figuring costs for flash and batt, 2" of spray foam, R-15 mineral wool, requisite furring and new drywall and came up with a total of $24K plus my helper's time as labor for some of that work at for at least $5K. This GBA post describes our exact configuration treated with high density cellulose except he has 2 x 6 rafters. https://www.greenbuildingadvisor.com/article/a-low-carbon-approach-to-attic-retrofits?show_account_panel=1 . If you go into his article, you will find a drawing called "roof section". He brings the cubbies behind the stem walls into the conditioned space. One interesting thing I noted as I was comparing the Washington State Energy Code, Residential Alterations and Additions sheet. The 2018 version I used for downstairs says cathedral ceilings must have all space in rafter bays filled except you must have 1" air space under the roof deck. The 2021 simply says you must fill all available space. I'd not want to use fiberglass or rockwool batts for that but after your comments, reading the article above, and considering time and money saved, might forgo the additional R value gained by tearing everything apart. With any drill and fill approach there's always the issue of getting all the voids. That's where I get to supervise. Also we have skip sheathing under a newer plywood deck so there will be voids there, but as you say, with cellulose, hygric redistribution and periodic drying can occur. I did install an HRV and scrupulously seal penetrations in walls and before adding insulation in our attics can look at and seal top of wall plates (not fun pushing old cellulose around). Finally, many of our cubby spaces simply have no ceilings so the rafter bays can be accessed from below for filling, then scrim put up to fill their ceilings. It's all going to be a ton of work but maybe with cellulose, not two or three tons of work gutting lath and plaster.
Arioda, I had initially written a longer response but when that one vaporized I was brief in recapping it. One thing I should have included is that unvented cellulose is not code-compliant, it's just safer than unvented open-cell foam.
Brandon Kavenaugh's project in the article that you linked to is what I thought you were describing, aside from the depth.
I used to work for a company (FoamTech in VT) that could inject closed cell urethane foam ...
Happy to answer any question about that technique
Here is another company that claims to be able to do it - Enverge ProFill® System
https://www.envergesprayfoam.com/Our-Products/specialty-products/profill-system
Thanks. That would be awesome if the cost were in line. Typical cost for spray urethane applied is $2/board foot. Looking online at DIY kits it's about $1.50/BF for the spray, and the injectable version is about the same for Tiger Foam kits. I haven't yet found any injection applicators near me but extrapolating filling our true 4" deep cavities would be $8/sq foot or about $24K for our project which is a lot. With kits and DIY it'd be about $16K or maybe less if we use spray foam in the open ceilinged cubbie areas behind kneewalls. The spray kits are a little cheaper than the injection material. The plus here is that the cavity R is ~27 vs ~15 with dense pack cellulose. Still waiting on quotes for that.
Commercial spray foam contractors are usually significantly cheaper per board foot than the DIY kits on any kind of larger job. The DIY kits really only make financial sense on very small projects. Rim joist jobs are usually around the break even point, and even then, commercial contractors are often cheaper if they aren't super busy.
Another advantage to using a commercial contractor is they are unlikely to run out of material before finishing the job. Almost no one gets the advertised amount of coverage out of the DIY kits, and I don't blame the manufacturers of the kits for this: it's very, very difficult, it not impossible, to get a perfect application with those kits and the manufacturers are using a PERFECT application to calculate the coverage of their kits. By "perfect application" here I mean the exact right thickness layer, in an exact right width path, applied perfectly evenly over the entire length. In actual use, you're going to get a lumpy installed layer of uneven width, which is absolutely fine in terms of insulating your project, but tends to use more foam and makes the kit run out sooner than you'd expect.
Bill
Thanks Bill for your comment. I'd definitely use a commercial contractor and have one lined up for spray foam, but no one for injected foam. They apparently do not exist around here. I was hoping to avoid pulling down lath and plaster as I have done enough of that in my lifetime but maybe cannot avoid it. The same problems or worse I think likely exist with the low/slow rise urethane foams for DIY injection.