Basement Insulation


Old 12-29-14, 06:38 AM
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Join Date: Dec 2014
Location: usa
Posts: 2
Basement Insulation

The builder of my new construction home wrapped the basement interior walls with insulation (fiberglass with white backing). I'm currently framing to finishing the basement into a living space.

My question is:

Can I add additional insulation in the wall cavity over-top of the currently wrapped walls?Name:  IMG_3632.jpg
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Thank you in advance for your help!
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Old 12-29-14, 06:46 AM
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Location: WI/MN
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Welcome to the forums.

Looks like the stud bays are full so I don't know how you propose to add more insulation. If you do, however, that plastic needs to be removed first.
Old 12-29-14, 06:51 AM
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Join Date: Dec 2014
Location: usa
Posts: 2
The walls you see in the image is pre-framing (I should have relayed that in my posting).
Old 12-29-14, 07:05 AM
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Then just remove all of the moisture barrier and you can insulate your stud walls when you build them.
Old 12-29-14, 07:25 AM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Are you sure you really need to add more insulation to an already insulated basement in such a mild climate? Keep in mind that your floor is about the same temperature or colder than the surface of the existing wall surfaces (and has more area).

Over-insulating of basements is very common and you lose the thermal inertia of the soil and walls in the summer when you want to keep the home cooler if you use central AC.

It is just a matter of where you want to split hairs and spend money on short term indicated insulation values (the "R value") for one of the 4 seasons.

Old 12-29-14, 09:47 AM
Join Date: Oct 2008
Location: New England
Posts: 9,995
Being new construction and since they determined years ago that foundation walls need to dry to the inside (as they cant dry to the outside below grade) here is an 06 Building Science article explaining why it shouldn't have been done that way.

There is also the issue that a new home has no history to know what moisture problems may occur. The tar on the outside has also been proven to not be sufficient as a moisture barrier.

Photo 3 shows what you have and photo 4 shows what you want.
BSD-103: Understanding Basements — Building Science Information

Old 01-10-15, 07:22 AM
Join Date: Jan 2015
Location: United States
Posts: 396
Bud9051 - this is very helpful for me as well....thanks for the link.

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