Spray Foam – Bad

Here is an email from a fellow green builder, Keith Winston, on the cons of spray foam. No matter how great they are for sealing, they have too many drawbacks IMO. The same sealing can be done with good tape, vapor barriers and caulk.

His email:
The foaming agents of small cans of foam (i.e. Great Stuff) are isobutane or propane. The foaming agents of proportioner-applied spf is the effect of heat, ambient moisture, etc (that is, there are no added gaseous foaming agents, either flammable as above, or refrigerants — see below). The foaming is done by a combination of a heated hose, pressure developed by pumps, and the mixing process (if anyone wants to give me more gory details about this part, I’m all ears). The trade-off is a big, expensive, somewhat delicate instrument called a proportioner, that takes up a truck or large trailer by the time all is done.

The other option are variations of refrigerant-blown foams: the “builder-packs” of foam, of say 600 sf, that come in (2) 5 gallon propane-style tanks (parts A & B), or in much larger 50 gallon compressed tanks etc. These are horrible, in my opinion, since these refrigerants (with high Global Warming Potential, though low Ozone Depletion Potential) are (by design) released 100% into the atmosphere during application. It can be the equivalent of several tons of CO2 for one kit.

I suspect that these are one of the fastest growing segments of the construction foam industry. I’d encourage people to try to get the word out and discourage use of these kits.

About the author: Gennaro Brooks-Church

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  1. Gennaro Brooks-Church - September 16, 2009 at 5:44 pm

    Just to clarify my overly simplified and alarmist title, not ALL spray foams are totally bad IMO. Eco Brooklyn actually uses a lot of Great Stuff can foam.

    The cons is that we use up a lot of cans and it is petrochemical foam with all the chemicals and environmental issues with that.

    The pros is that as far as spray foam goes, the cans are actually the least bad. The DYI “builder packs” you can buy over the internet are really bad.

    The other option is the professional grate set-up which costs thousands of dollars and isn’t much use for weather sealing and old house. They are just overkill and IMO are only really useful for new construction (=bad). Some might say you can use it for sealing an old house but in almost all the cases I have seen you can do it with cellulose which is much greener.

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