Insulation, Radiant and Vapor Barriers - Zonolite / Vermiculite

Hi,
I have an existing hollow block wall, and a space between two block walls, that I would like to insulate. After some looking around on the Internet, it seemed that vermiculite or perlite was a good bet for filling the wall and space as it apparently flows well to fill all spaces.

So I called and asked my local building supplier about it. Sure enough he was familiar with it and said he had a store that stocks a product called Zonolite that comes in 4 cubic foot bags at about $7 a bag, and it could be delivered to my place.

Great! Well, until I got on the Internet again and found that Zonolite is a huge concern for owners of homes with Zonolite installed in previous decades as it may contain asbestos and should be tested.

Surely the Zonolite my building supplier has today must be asbestos free, but I haven't found anything yet about the current product. I believe by law it is supposed to be asbestos free. I didn't bother asking my building supplier because he has a bunch he wants to sell.

Can anyone tell me anything about the current Zonolite produce? Searching for it on the net just results in lots of info about concerns with existing installations of it.

Thanks,
Bill

Zonolite is a term developed by the manufacturer for vermiculate that has a waterproofer added to it. The first thing to check is if vermiculite (the stuff in potting soil) is allowed in a building as insulation.

Perlite is a better insulator, when compared with vermiculite, but it is more costly and difficult to find for small jobs. It is more for commercial/industrial applications like cryogenic vessels.

You could also consider foam, but they can have severe shrinkage or expansion problems depending on the type.

I would think that there would not be as much of a problem with vermiculite in a masonry wall, while it can be a problem in a temporary wall like wood frame.

Dick

Vermiculite is a dirty ore often with asbestos or other minerals, so who knows if today our vermiculite is still safe, you have to decide for yourself.

However, Zonolite was a brand name of vermiculite from Libby Montana, manufactured by W.R. Grace. Zonolite is contaminated with tremolite asbestos, and as such is not safe for use.

Of course, he might just be calling a newer vermiculite "Zonolite", just as we call facial tissue by the brand name "Kleenex" quite often. Or, maybe it is old stock. Naturally, the old stock should not be sold for obvious reasons, but you never know.

So basically, vermiculite is still produced and some is not contaminated and safe, but "Zonolite" is no longer manufactured, as it again, was tainted with tremolite asbestos.

Whatever you do, be careful of asbestos and good luck with your project.

Since posting, further information I have found indicates that all vermiculite sold today comes from mines that are tested for the presence of asbestos. It seems the Libby mine so far is the only mine that produced asbestos tainted vermiculite.

Zonolite stopped being produced in 1993, however I found one report of it showing up on store shelves as late as 2001. So as Codyy pointed out, the supplier may have been using the term for any brand of vermiculite.

Vermiculite has been used as insulation in residential construction as far back as the 50's from sources I have read, possibly earlier.