We have just insulated our shed and put vapor barrier inside the
insulation, with a layer of tar paper between the insulation and the
siding. We are noticing that one wall is sweating and moisture is
collecting between the insulation and vapor barrier. Berfore we
drywall, we want to eliminate the moisture. The attic of the shed is
vented, so I can not understand why we are seeing this moisture
still? Does anyone have any advice as to how to fix this and why we
would still be getting moisture? We would like to use the shed as an
office and have also installed heating. Are we still lacking proper
venting or is this likely because we have not properly sealed the
vapor barrier? Thanks in advance for any help.
If for some reason the air outside is warmer/wetter than it is inside, you
could get condensation on the 'outside' of the VB. Another possibility is a
water leak into the wall, from above, or from wind driven moisture through
Thanks for the reply Michael,
We have had the heat on high so it is definitely warmer inside and the
moisture is a sweat on the whole wall, so we have ruled out any
leaks. We have just replaced all VB and insulation trying to solve
this problem and it is back again. Thank god we did not put up the
I am here asking questions myself, so do not presume to know the answer,
If the insulation was previously made wet, it would stand to reason that you
would get renewed moisture on the VB after re-sealing the cavity. Under
this scenario, you would have even more condensation on the felt paper under
your siding. Another, albeit unlikely, source of moisture is the lumber
used to make your wall. Perhaps if it was quite green and got a good
soaking prior to being sealed in. If you were to open things up yet again,
make sure to let everything get bone-dry before putting up a vapor barrier.
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