Vapor Barrier

Old 01-28-02, 05:58 AM
Visiting Guest
Posts: n/a
Question Vapor Barrier

I have read several messages regarding the placement of the vapor barrier. Can anyone clarify if where it should be placed if using a thin poly barrier? I have applied a sealant (Dryloc) to the floor and walls and was thinking that the next step would be to line the walls with a thin poly "vapor barrier before proceeding to frame, then roll in fiber insulation and then drywall. Is this wrong? Which comes first, the plastic barrier or the insulation? Thanks.

Old 01-28-02, 07:55 AM
Join Date: Aug 2000
Location: USA
Posts: 15,047
Upvotes: 0
Received 2 Upvotes on 2 Posts
Installing vapor barrier on basement walls

Vapor barriers always go on the heated side of the area you are insulating. Studding and insulating basement walls make them colder so condensation is more likely to form on them if vapor enters wall cavities. This can cause insulation to become ineffective and may cause mold/mildew and decay. Vapor barriers do not take care of water vapor entering wall cavities. Air leakage into wall cavities causes moisture. It is recommended that you seal all penetrations of the walls. Thus, some recommend not placing electrical outlets and switches on outside walls.

Go to for helpful info.
Old 01-28-02, 07:58 AM
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: USA
Posts: 1,820
Upvotes: 0
Received 0 Upvotes on 0 Posts
The insulation goes first then the vapor barrier. The primary purpose of the of a vapor barrier is to prohibit warm air from the conditioned area entering the insulation. Which is the primary source of condensation in insulation.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: