Replies

1. 
   DanH | Aug 11, 2009 04:28am | #1

   Consider that a part of the problem is simply that the floor is so much colder than the rest of the house.

   As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
2. 
   brownbagg | Aug 11, 2009 05:15am | #2

   http://www.stegoindustries.com/photo_gallery/a_field_of_yellow.html

   this is what we use, but it is a performance vapor barrier, not your everyday plastic
3. 
   mike_maines | Aug 11, 2009 03:14pm | #3

   Try this:  tape a 24" square piece of 6-mil poly onto your slab.  Wait a couple of days, and see where the condensation occurs.  If it's under the poly, you need a well-sealed vapor barrier (6 mil poly should be fine). 

   If condensation occurs on top of the poly, Dan is correct, and you have moisture precipitating out of the air.  Reducing the humidity level in the house would be wise in that case.

1. 
   tjem | Aug 19, 2009 12:46am | #4

   ok thanks - I have taped down some 4mm poly (hope that will do) and will check for moisture. During the summer we run at 60 to 70% humidity down there. From what I read on the net that may be to high to put down engineered wood even if the slab is dry?

1. 
   mike_maines | Aug 19, 2009 12:54am | #5

   4mm should suffice.  The thinner it is the more it "breathes" which may change your results slightly but probably not by much.  If you get condensation on top of the plastic, and I suspect you will, you probably shouldn't install your floor unless you install a dehumidification system of some sort.