Housewrap for basement reno

mashedthumbs

I'm adding a basement room. Any pros/cons or why bother to adding housewrap between the new stud walls and the basement walls (concrete block)? Thanks...........

TheCamper

I assume that you are converting an unfinished basement that is substnatially below grade to living space.

House wrap is typically used on the exterior of the home, e.g. over the sheathing, for the purpose of preventing wind infiltration and keeping water from the sheathing and thereby rotting it. A proper housewrap allows moisture to vent through it from the building side to the exterior side but does not allow moisture from exterior to pass through to the building side.

What you usually want on the interior side of walls of a living space is a vapor barrier. Habitable space generates humidity through the occupants' activities such as respiration, cooking and showering. Heated air holds more humidity than the colder air, therefore if the interior air leaves the conditioned space and enters into that cooler wall cavity (cooler because it is adjacent to the exterior) the relative humidty goes up it may condense inside that wall cavity. Dampness in the wall cavity can cause rot and mold and damp insulation does not insulate effectively. A properly installed vapor barrier keeps the humidity inside the habitable space.

Prior to starting any work you will want to determine if you have a moisture problem in the basement. If you have moisture penetrating into the interior space of a basement and do not remediate it prior to finishing the space you will have a damp moldy finished basement.

Let me know if this doesn't address your question. Good Luck with the project.

Ron Franck

I agree with Camper. Normally. you would build your studded wall, fill the cavity with insulation and then apply your vapor barrier. I would not think house wrap to be the most suitable material in that application.
If money isn't an issue I would favor a spray foam insulation.
Also, correct any moisture problems before construction.
If mold has at one time or another been present you should treat the area as the mold spores can remain dormant for extended periods of time only to re-occur when conditions are favorable for renewed growth.
Ron

Gary in WA

You don't want a housewrap on the concrete. Tyvek has a permeability of 58, Typar- 14. These products are vapor permeable.... +10 perms. You want a sprayed foam (1.5 perm.), 2" thick, as Ron said, or a rigid foam board (1.1 perm) to slowly release the moisture to dry to the inside: http://www.buildingscience.com/docum...ent-insulation
The housewraps are a water barrier that let water vapor (moisture) go through both ways, they are vapor permeable. If you seal the seams, they can also act as air barriers. In your climate, you don't want a vapor barrier. http://www.buildingscience.com/docum...ecommendations

Be safe, Gary

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