Least toxic closed cell 2-part spray for DIY?
agurkas
| Posted in Green Products and Materials on
All the reading I have done, I see a lot of issues brought up with 2-part closed cell spray foam being kind of bad for you even with respirator.
I want to do the band joist in my crawlspace and with only entry door there isn’t much room for ventilation. I need about 500 board feet.
Any recommendations for least toxic (fire-rated preferred) 2-part closed cell spray foam?
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Replies
No such thing. Just don't spray it during the winter. Cold surfaces are not great to spray on. You would be better of and less toxic to use rigid foam, one part sealed in place. Read at GBA the misting one part with water as it is expanding increases the yield. Seal with caulk first, then rigid sealed in place then dense batts. I have also had my spray folks do a small job to empty the barrel for a great price.
Anyone that uses the word toxic .... go rigid... go rock wool...
Most of the DIY foam kit vendors buy their chemicals from the same source, and there is very little "special sauce" tweaking that goes on- it's more of a packaging, sales, & customer support thing that the big chemical vendors don't care to get into.
Pay close attention to the installation recommendations for both the surface temperature and chemical temperature when doing DIY foam. As AJ points out, the middle of the winter is about the worst time to do it, since the temperature of the band joist will be all over the place, and not necessarily in the appropriate range (even if the room temp is.the right temp.) When both the outdoor and indoor temps are in the 65-75F range it's a pretty good bet that the band joist will be too.
In any season when using the 600 board-foot kits it's useful to put the tanks in a tub of water that's at the high end of the recommended chemical temp range, since the tank temp will otherwise drop as the chemical is dispensed. The thermal mass of the water will keep the tank temp up as it pulls heat from the water, cooling the water as it warms the tank.
I was thinking about doing rigid foam, but my band joist looks like in the picture below. Apparently in the 50s that is how they chose to "fire proof". Bricks and mortar placed haphazardly. Empty wall cavity above.
Also, the top sill has gaps all over and you can feel the draft going up those bricks.
Both pieces of advice given by Dana and AJ are right on. They should be adhered to. But I think the problem that leads to the very worst and most toxic houses after 2 part spraying is a badly adjusted ratio of the two parts or running out of one element in the two part element and not knowing it. In my own mind I haven't understood how you can determine ahead of time if one element has low flow or has terminated. Maybe there is a way to know but my intuition is that it probably just comes with experience. That's why the long term house toxicity problems with 2 parters has to do with proper installation and not with the chemicals themselves. It would be a complete disaster if you did a whole house without the proper ratios. It might not even be livable afterwards. I think AJ's advice about the risk is worth taking seriously.
I guess I should add that poor mixing of the correct ratio of the two streams will cause the same problems as a bad ratio. A lot can go wrong it seems to me if it's your first time. Admittedly I don't have direct experience using a two part system, I have to admit that, but the consequences can be so bad if you don't get it right that I wouldn't risk it myself. Usually you can get away with just using the school of hard knocks, but I don't think this is one of them.
"Foam it Green" adds yellow and blue dye to the two parts, so the resulting foam is supposed to come out green if you've got the ratio right.
I was looking into it myself this morning, trying to decide if I should go for spray foam for my rim joists... I'm willing to pay extra to save myself some time, but the conclusion I came to was that it would be a huge hassle to use the 2 part kits, and the overhead costs for small kits makes them more expensive than canned foam of the same volume.
Also note that the two-part foam kits have high global warming potential blowing agents (~1000X the effect of CO2), whereas the one-part canned foam has negligible global warming potential. Considering that and all the other challenges people have noted, it doesn't sound like a good idea to me use those kits.
One of the major spray foam sources, Lapolla, has recently come out with a low-global warming potential HFO based spray foam http://www.lapolla.com/foam-lok-2000-4g/ so if you go with a professionally applied spray foam from someone that uses Lapolla's products, it should be possible to specify that. And you presumably greatly reduce the risks of poor mixing, etc. when it is applied with professional equipment.
The HFO blowing agent is not likely to be available in the off-the-shelf kits in the near future, because HFO has a short shelf life.
My goal is to seal well and encapsulate the crawlspace. Right now it causes massive drafts. Floor in the bedroom above it is always really cold.
Spray foam seemed like the easiest option, considering it isn't the typical nice band joist. But sounds like I need to go back to the drawing board.
Apollo,
You should listen to everyone's advice, and then make your own decision. Most homeowners who use two-component spray foam end up with good results. Here is a link to an article describing a successful project:
https://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/basement-insulation-part-2