Injection open cell foam for Michigan 1990s home without exterior home wrap?
I have a 1990s house in Michigan. I have fiberglass insulation in the walls, which is not terribly effective and results in some cold spots and draftiness in the winter. I’m considering having a foam company pull my siding to install injection foam (i.e. open cell foam squirted into the joists in the walls from the outside of the home). However, I am concerned about the potential for mold or other hazards. My house does not have exterior home wrap, meaning if you pull siding, you just see the wood sheathing, but in at least some places does have a wrap on the interior of the sheathing, meaning if you open up the wall cavity from the inside you can see white plastic wrap. I know this is unusual and I’m uncertain why it was done this way.
Assuming my home has wrap on the inside of the walls, would installing injection foam pose any greater risk of mold inside the walls than the fiberglass that’s in there now?
Assuming only part of the house has wrap on the interior and other parts have no wrap at all, would installing injection foam increase the risk of mold?
Finally, what’s the current thinking on the risk of off gassing or other exposure to occupants from using open cell foam in this manner? Any significant risk of exposure to fire retardants or other hazards?
Thank you!
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Replies
Is this the company?
https://usainsulation.net/insulation-services/injection-wall-foam
Coldhouse,
If you are taking the siding off and exposing the exterior, a better solution is a layer of foam board. This lets you use the exiting batt insulation, reduces thermal bridging, and leaves the sheathing intact, which can be used as an effective air-barrier.
Typically when you do this you just remove a course of siding every 3 to 4 feet (not all the siding)
https://www.youtube.com/watch?v=6jXbvaVD5vE&t=147s
Advance to the 1:50 mark in the video - they are showing removing a course of vinyl siding ...
begreener,
If he has no WRB then the siding should come off anyway.
The other complication is the existing fiberglass batts. Injection foam proponents say their presence doesn't matter, but the argument for that always seem a bit unconvincing.
Can you see any writing or logos printed on that white plastic?
You can dense pack cellulose over old batts. Pretty much similar install as the foam without any of the potential foam issues. Cellulose can also do a bit of moisture buffering and redistribution which can help with your wrb issues.
Dense pack is also air retardant, doesn't seal as well as foam does but good enough. A while back I dense packed an old ballon framed house and the difference was night and day, walls and windows you could not sit near before were now perfectly comfortable as it stopped the drafts.
I'm very suspicious that injection foam will do a good job in walls that already have insulation in them. The existing insulation is likely to bunch up and block the flow of foam into various areas, leaving voids. You may get some improvement, but I think you'll be limited due to missed areas and air leaks that weren't sealed. I think injection foam is much better used in walls that are currently uninsulated.
I'd be more likely to try dense pack than injection foam, because Akos has experience with it, and I'm more trusting of the judgement of some of the professional members on this forum than I am of marketing materials put out by insulation companies. Remember that the members here don't have any agenda or incentive to try to sell you anything, so they're usually just trying to give you good advice.
I think Malcolm is right about the best option being installation of rigid foam on the exterior. This is likely the most work, since it becomes a reside project and trim details will need to be dealt with too, but it will get you the best overall performance and will also let you add a WRB (which rigid foam can often double as). If you have the budget for it, this is what I would do. BE SURE to put AT LEST enough rigid foam for your climate zone, but more will get you better performance. Anything up to about 2" thick isn't too difficult to do. Over 2" thick and you're into "thick" foam territory which complicates trim details. Use a bead of sealant around the perimeter to air seal things, and tape the seams between rigid foam panels.
BTW, using reclaimed materials here can save you money. I'm a big fan of reclaimed polyiso for projects like this.
Bill
It sounds like your comfort issues may be primarily due to air leakage. Have you had a blower door test done? If not, I would start there and address air leakage.
https://www.greenbuildingadvisor.com/article/blower-door-directed-air-sealing-2
Thank you all for the responses! I am most grateful. To answer the questions raised:
1. The company I'm considering hiring is Retrofoam.
2. As others have noted, the company would just remove one strip of siding on each floor of the house, drill holes, inject foam, and then replace the wood plug and siding.
3. Cellulose would have fire retardant treatment as well, correct? Are there concerns about that (or foam) exposing occupants to those contaminants in significant amounts?
5. Wouldn't cellulose have the same issues with humidity and mold? One thing I don't grasp is why, if I haven't had mold develop over 30 years, adding more material into the wall cavity would prompt mold to develop.
https://www.retrofoamofmichigan.com/blog/retrofoam-applegate-tripolymer-best-insulation-existing-walls
Comparison of three different injection foam companies ...
This is not the same type of foam as spray foam ...
3- Yes, it's treated with a fire retardant. AFAIK, no one has ever had any issues with the stuff they use in modern cellulose. Remember also that the cellulose is going to be sealed up in the wall, so you're not really directly exposed to it regardless.
4- Where is question number 4? :-D
5- Cellulose can "buffer" moisture more than fiberglass or mineral wool can (or spray foam). That means it can help to control condensation, sort of like how placing a sponge under a dripping faucet can prevent a puddle from forming, up until point at which the sponge gets saturated. Most other materials allow moisture to migrate through them without any buffering, and then the moisture will condense on the first cold surface it "sees" in the wall. Insulation slows heat loss from the home, which makes the cold surface of the inside face of the exterior sheathing colder, making condensation more likely. That's where you can run into problems. Cellulose's buffering capacity helps to mitigate that issue.
Bill
I was curious to see what these are and had to go down a pretty deep rabbit hole to find out. I know some spray foam manufactures also like to hide what the material is and hide behind words like soy and rosehip water but this was even next level.
Looks like most of it is urea formaldehyde foam. This is the same stuff that caused the UFFI issues many decades ago. It does sound like the issues with off gassing has been fixed since then so at least it is better. Shrinkage is still an issue which would effect how well it air seals on the long term. It does sound like a good solution for masonry buildings though, not sure about wood construction.
I would stick with dense packed cellulose if you can find a local installer.
There is no hard and fast rules where walls will fail. Lack of WRB is not an issue if not much water makes it past the siding and wall has decent drying ability. Having either lumber or plywood sheathing also makes a big difference. Sometimes leaky assemblies are your friend as the extra air and heat flow can improve drying.
When insulating older walls, the thing to watch is your window flashing details. These are important if you have a lot of wind driven rain or if there are exposed windows such as bay windows on a two story house.
https://www.retrofoam.com/blog/retrofoam-canada-lawsuit-formaldehyde
excerpt:
"“The resin that is used goes back to the 1930s. Those original resins had a lot of formaldehyde in them,” Edmunds said. “The ones used for RetroFoam were developed in 1979, and they found a way to make the resin a lot stronger. RetroFoam has been improved on over the years to make it more environmentally friendly.”
Edmunds went on to explain that the RetroFoam resin is fired in a kiln, which seals the formaldehyde in the powder. When the resin is mixed with water, it will release formalin, which is formaldehyde, but it is dissolved in the water.
The only time formalin is released is during the mixing process, which takes place outside of the home in a controlled environment inside of the trailer.
The finished RetroFoam injection foam insulation does contain 0.06 ppm of formaldehyde, but it is sealed inside the cured foam. RetroFoam is considered to be formaldehyde-free because the gas is bound in the polymer, so once it cures, it can’t off-gas or escape into the home, and it is not detectable.
“There is formaldehyde in the chemistry,” Edmunds said. “Formaldehyde-free is fine to say because it doesn’t release into the environment.”"
https://www.greenbuildingadvisor.com/article/a-vilified-insulation-material-from-the-1970s-returns
https://tripolymer.com/
https://www.core-fill500.com/
https://www.cfifoam.com/
https://www.retrofoam.com/