Best overall CCSF
I know this has been discussed numerous times but there seems to be a handful of new formulations that have been released recently.
So what’s the best overall these days?
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Spray foam is the most expensive way to insulate the smart move is to avoid it.
With some planning in new construction there is almost always a better way to insulate at a lower cost.
Like Walta says, the best spray foam is no spray foam. There is usually an alternative that's better for the environment, healthier for installers and does not risk an improper cure, which is rare but happens often enough to be a concern, as remediation is a giant PIA.
If you have to use foam and open-cell will work, that is best in terms of environmental impact, but there are few situations where it's the best choice overall.
If you have to use closed-cell foam, any product with an HFO (hydrofluoroolefin) blowing agent is much better environmentally than the previously most common formulation using HFC (hydrofluorocarbon) blowing agents.
Many manufacturers offer at least one product line with soy as an ingredient, but that's mostly just a marketing ploy and has little effect on the actual environmental impact.
Some manufacturers offer a density between open-cell, which weighs around 0.5 lbs per cubic foot, and closed cell, which weighs around 2.0 lbs per cubic foot, with water as a blowing agent. It's not really closed-cell and the R-value is pretty low so there are few situations where it's a good choice.
All manufacturers offer products for different temperatures, which is just a factor of the weather at installation.
Hi guys, I appreciate the comments. In my local building climate, zip R9 plus 2" flash and batt CCSF is the same price or actually lower than doing zip + 3" of exterior insulation. 3" rock wool 4x8 sheet is $130, 3" EPS is ~$65/sheet. Labor is the real a killer here and I haven't found single contractor familiar with exterior insulation installations so the labor is even higher. I could DIY but my time is even more expensive than contractors so I would rather not do it. Exterior insulation gets even more complicated when we want to do vertical wood siding and masonry.
Regardless if I choose to do the walls in CCSF, I will be using it in below grade areas since it's so perfectly suited for those installations where vapor and radon is a major issue.
Does anyone have any experience with the "natural polymers" product? Or is that just another flavor of HFO foam?
"Natural polymers" means they replaced some of the petro-chemical resin with soy-derived resin. There is a tiny improvement in embodied carbon emissions and no changes to the result that I know of, but the difference in embodied carbon is very small.