Vapor barrier or not, you'll get condensation on the surface if the slab is
cold and the weather is warm and humid. By your description, today's
conditions were perfect for a sweating slab.



"Ray" wrote in message
...
I had a slab (30' x 32') poured with a vapor barrier last January. Since
then I have built a metal building for a workshop on it. Today I noticed
that the slab was sweating and it was my impression that the vapor barrier
is suppose to deter the sweating.

The slab is in a workshop that is not climate controlled but the roof has
fiberglass insulation. I live in South Louisiana and we had a snowfall on
Xmas Day...very very unusual for this part of the country. The snow was
all
gone by the next day. The temp today is in the low 70's.

Could the frost (snow) had something to do with the concrete sweating even
though it has a been a week since the snow ??

Please advise.