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Posted by The Insulator on January 29th, 2000 03:17 PM
In reply to CONDENSATION BETWEEN INSULATION & VAPOR BARRIER by JAY on January 27th, 2000 09:04 PM [Go to top of thread]

Moisture in the walls of the foundation is a 2 fold situation. Ground moisture can enter from the outside, especially on a non-waterproofefed or cracked and leaky wall (This is more common with block foundations).

the moisture your experiencing appears to be from condensation. You've installed the insulation without anything to stop air convection from reaching the cold surface behind it (the insulation has effective isolated the back surface from the heat making it colder then it would be w/o insulation). Depending on the type of wall material used, once the wall is on, you block most of the convection.

Should you remove the poly behind the insulation. It partially depends on how groundwater tight the foundation is. I would suggest at least removing any poly that extends above grade, allowing the vapor to breath out from that point.

Should you poly the inside. Some states have changed their codes, eliminating the need for a vb on basement walls. I still install poly based on the reasoning the best way to eliminate moisture in the walls is to prevent it from ever getting there. It also depends on the materials to be put on the walls. Drywall (Taped) is relatively airtight and stops convetion, T&G wood and sheet paneling is not, and therefore needs an the airtightness the poly gives.

Also, be sure to make any penetration thru the wall (Outlet & switchs) as sealed as you can.

The Insulator

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