Dimitri Magiasis

Thank you so much for sharing your experience.  I did a quick test sample and it seemed like if I used about 3" of perlite, it compressed to 2 ½".  I'm technically going to use a hair over 3 ⅛" of perlite, so I think it will compress to that and if it's a little more, then I guess I will do a thicker finish floor (I doubt it would compress more than 1", but who knows after you put all the weight of the subfloor on there).  Also, I already have 6ml plastic (therefore, don't have to buy more) and hoping that would be good enough, though 10ml sounds pretty stout.
Thanks again!
Dimitri

Hi,
I'm in the process of creating a mudroom.  I live in a wet climate in western North Carolina.  I wanted to go for a more natural ground insulation, so I chose perlite.  Currently, I have 3 ½ inches of gravel against the ground.  I was planning to put a little sand on top and then put a 6ml poly vapor barrier.  Then, I was going to put on 3 inches of perlite and then an earthen subfloor that is mostly comprised of road base, clay slip, and lime.  I was going to do a low moist mixture to tamp it and then allow it to dry fast.  
I know that perlite can wick water, but what about pulling in moisture from the air.  Will that be a problem if it's directly below the earthen subfloor and be able to grab moisture from the air through the earthen floor?  Will it compromise the lime subfloor?  FYI, eventually, I will put a finish earthen floor oiled and sealed on the top.
I guess I'm having a hard time imagining it to be a problem, since clay can absorb moisture from the air and we use that for plasters and such.  In some ways, these earthen materials help to regulate the humidity in the air.  Curious to hear any significant concerns if there are any.
Another option could be to put the perlite on top of the gravel and put the vapor barrier on top of the perlite, but I worry about the tamping and how that might create tears in the 6 ml plastic.  
Thanks,
Dimitri

Thanks for your thoughts.  Yes, 3 ½ inches of gravel underneath.   Appreciate your response.

I'm going to put in an earthen subfloor (basically road base with lime and clay slip) on top of perlite.  On the sides, there will be a vapor barrier that will gp over the cement block foundation and then over a treated wood sill and pine bottom plate.  Is the 6ml vapor barrier enough separation for the earthen floor from the wood sill and bottom plate?  I have rosin paper as well.  Do I need to add that in this application?  If yes, how so?
Thanks,
Dimitri

Hey Ernie,
Did you put a vapor barrier above the perlite?  I'm curious if you put the base floor directly onto the perlite or did you put it onto the vapor barrier.   Wanting to ensure that doesn't cause cracking.
Thanks,
Dimitri

I just got perlite insulation and see that you put the vapor barrier on top of your perlite.  I have two questions, does that mean you put the perlite directly above the gravel and then you put the vapor barrier on top of the perlite?  A lot of times in natural building, having something for the materials to grab onto seems essential (e.g. plaster on a cob wall or burlap, but not on bare wood).  Putting a base floor onto a vapor barrier seems counterintuitive.  Maybe gravity is holding it down?  So, were there any issues?  Cracking?  
Thanks,
Dimitri