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Dimpled membrane any good for interior foundation?

Dimpled membrane any good for interior foundation?

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  #1  
Old 07-29-17, 06:28 PM
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Dimpled membrane any good for interior foundation?

I don't like any kind of wood (PT, blue, green etc) touching the porous concrete. Would it be a good idea to put dimpled membrane against the interior foundation and put foam board in top of it, then put stud on top, and another layer of foam between the stud. I hate any kind of fiber glass for below grade.
 
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  #2  
Old 07-31-17, 06:00 AM
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Best to check with the local AHJ. Sill gasket is allowed, don't know about anything else under a base plate.
 
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Old 07-31-17, 06:06 AM
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If I understand correctly it's the inside of the foundation wall and not above it.

IMO it's better to build a stud wall with a small air space behind the wall.
 
  #4  
Old 07-31-17, 07:20 AM
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The foam board directly against the foundation wall provides both the separation to keep the wood away from the concrete and acts as a vapor retarder that will allow a small amount of moisture to pass (very small). IMO, the dimpled membrane against the wall is usually used when there is a known water issue that needs to drain to a provides system at or below the floor.

Adding more rigid reduces the drying to the inside. Consider applying the rigid against the walls followed by framing against that with stud cavities filled with Roxul. I try to avoid any gap between the framing and the rigid foam to limit any air circulation.

Air seal and insulate the rim joist cavities and add fire blocking if codes require it.

Bud
 
  #5  
Old 08-01-17, 02:28 AM
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If u put foam board directly against concrete wall, because concrete is porous, will the moisture get trapped between two layers forever and not have a chance to dry out?

If u put dimpled membrane against the wall and floor, there is space so moisture will not get trapped, and moisture would go to basement floor and into sump pump.

Why does adding more rigid foam makes the inside less dry, isn't the thicker the foam, the less moisture will pass thru? And isn't Roxul not as good as a moisture barrier as rigid foam?

Basically I'm thinking dimpled membrane will direct moisture into sump pump, and foam will just trap it. But dimpled doesn't really insulate the cold, so u need to put foam board on top to insulate.
 
  #6  
Old 08-01-17, 03:56 AM
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A lot of questions and perhaps the best way to answer is with a science link. GBA is one of the better authorities on building sciences.
How to Insulate a Basement Wall | GreenBuildingAdvisor.com

Bud
 
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