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WJW 07-16-2012 10:48 AM

Vermiculite or Pearlite???
Anyone have a preference or know which does a better job insulating when being used dry (i.e. not mixed into cement...just poured into the airspace around the oven)?

I'm finishing the outside today and am putting a cage over the top with about a three inch airspace above the ceramic blanket. I also have some voids on each side of the entry area. So I'm filling that with loose insulation.

I was just at the garden supply place and they had both pearlite and vermiculite. 4 cubic feet of pearlite for twenty-two dollars...or 3.5 cubic feet of Vermiculite for thirty five dollars. The pearlite looks like it would trap more air and I liked the size of the individual particles better. So that's what I went with. Three bags totalling 12 cubic feet.

It seems like the vermiculite would hold up better if I were mixing it wih portland to make vermicucrete, but used dry I went with pearlite. Anyone have any experience or thoughts?


Neil2 07-16-2012 10:55 AM

Re: Vermiculite or Pearlite???
Loose or mixed with portland cement, either will do the job. Go with what ever is cheaper.

WJW 07-16-2012 12:26 PM

Re: Vermiculite or Pearlite???
Thanks Neil. I guess I should have done a search. It looks like there about fifteen threads.

The seaches I have done seem to indicate that Perlite is a marginally better insulator than vermiculite, but close enough that t doesn't matter and (as noted above) close enough that the cheaper one is probably the best choice. It looks like perlite is usually the cheaper.


cnicholson 08-10-2012 09:43 AM

Re: Vermiculite or Pearlite???
Probably a bit late at this point but there is a place called American Horticultural Supply (I think they are up that way too) and a 6 cf bag of Perlite is $20... cheapest I had found or even heard of on here. One caveat- they say they are wholesale only and have a minimum BUT, as one would expect in our economic climate, you walk in ready to buy and I have bought as little as 1 bag from them....

FYI...Vermiculite in a 6cfr bag is $38.

berryst 08-10-2012 11:42 AM

Re: Vermiculite or Pearlite???
I think vermiculite is a little close to asbestos chemically so I'd go pearlite but I'm sure there are others who know more about this than me

david s 08-10-2012 02:15 PM

Re: Vermiculite or Pearlite???
Perlite is a better insulator dry than vermiculite, but once you start mixing cement with it the result is almost the same. I'd be going for perlite if added dry.

Neil2 08-11-2012 10:50 AM

Re: Vermiculite or Pearlite???
"I think vermiculite is a little close to asbestos chemically.."

Not at all related.

cnicholson 08-11-2012 08:25 PM

Re: Vermiculite or Pearlite???
Yeah..I think saying vermiculite and asbestos are related is like saying tuna and dolphins are related...from what I understand they occur in the same natural environment so when one was mined the other was present...until "they" found out asbestos could make the lawyers A LOT of money.... Uhhhh, I mean was dangerous, "they" found a way to isolate the vermiculite...

Spinal 08-11-2012 11:33 PM

Re: Vermiculite or Pearlite???
The issue with Vermiculite and Asbestos is an often confused one - usually people say vermiculite CONTAINS asbestos though...

A few years ago, a few of the vermiculite quarries were found to contain asbestos as well; thus a lot of the vermiculite on the market also contained asbestos. If you are re-using old vermiculite, there is a chance it contains asbestos - yes.

That said, if you're buying new vermiculite, unless you are being sold 30-year old stock, it will have no asbestos in it.

Oddly, pearlite is in a similar situation... but people rarely quote perlite as having asbestos in it...


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