Finishing new basement

[Anonymous]

Wg,
Have a new basement and want to finish it . However old posts have concerns about trapping mositure. Was planning to put vapour barrrier on floor and concrete walls ( to keep out dampness ) and insulate. Should I also have a vapor barrier on the inside of the wall to keep room moisture from getting into the walls ? Plan to use the blue foam in the floor ( standard strapping ) and pink fiberglass in the walls.

PS Outside foundation was was waterproofed with a tar like substance. Don't think basement floor willl have vaour barrier under it .

[Wgoodrich]

Problem about thinking but not knowing may cause you great harm.

If a plastic sheet was installed under your concrete floor as required then you add a plastic sheet on top of concrete floor you would be trapping moisture. This would cause mold and mildew in that trapped area. Unhealthy !

If your basement wall is purged then no vapor barrier should be installed inside the basement walls unless a 2" air gap is maintained between basement walls and studded walls to allow moisture to excape. The purging on the outside of the basement wall is a vapor barrier form.

Insulating the floor on top of the concrete should not be done unless you frame a wood floor again with a 2" air gap between concrete and raised framed floor.

Can you contact you original builder to find the info you need concerning insulation and vapor barriers on the outside of the basement walls and under the concrete floor? If so do so. If not then create the 2" air gap for the concrete to breath and moisture to escape then build your insulated vapor barried floors and walls.

Hope this helps

Wg

[Anonymous]

Wg,

Building is still under construction .Basement is to be poured soon ,but I don't know if the builder will put down that sheet of plastic first. He will if its a local code requirement .
Foundation walls have been parged with a tar like waterproofing compound. But I thought plastic would keep even minimal dampness from the blocks themselves from getting into the basement. Walls are block not poured. Wouldn't moisture be able to move up the hollow center?
Didn't know an air gap is required before insulating a basement floor. Most just seem to lay down the blue foam. However I have a 10' basement so there is plenty of head room to play with .

[Wgoodrich]

R506.2.3 Vapor retarder. A 6 mil (0.006 inch; 152 m)
polyethylene or approved vapor retarder with joints lapped
not less than 6 inches (152 mm) shall be placed between the
concrete floor slab and the base course or the prepared sub-
grade where no base course exists.

If you basement walls are still not back filled you should read the building article on our www.homewiringandmore.com web site linked below. This is required by Code and will ensure a dry crawl space.

http://www.homewiringandmore.com/building/footingdrainage/index.html

Hope this helps

Wg