Basement remodeling questions


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Old 03-23-15, 10:07 PM
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Question Basement remodeling questions

hi all ~

I'm just starting a basement finish project and need some help starting ~

My basement already seems to have some insulation done, with 2x4s along the exterior concrete wall. I assume that I need no additional exterior framing, and can just add the perpindicular framing to the exterior walls for the room dividors?

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I also attached pictures of the basement floor, which has a single layer of OSB on top of the concrete. Once the walls are framed on top of this layer, can I just add carpeting immediately above this OSB, or do I need additional insulation/layers?


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Thanks in advance!
Justin
 
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Old 03-24-15, 06:21 AM
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Is the OSB in direct contact with the concrete floor or is there a sleeper system installed under it? Anything other than pressure treated wood in direct contact with concrete will fail over time.
 
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Old 03-24-15, 07:56 AM
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Thanks for the reply, czizzi!

I am confident that the OSB is not directly against the concrete -- our footsteps clearly echo like there is plenty of airspace under there for sound to travel.

That being said, I did not have a chance yet to pull up a board and visually confirm that the OSB is not in direct contact with the concrete -
 
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Old 03-24-15, 08:08 AM
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Old 03-25-15, 11:59 PM
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How to I frame around walls which are insulated with Blanket Insulation? Do I just add some separation between the insulation and the wall, rather than frame directly against the wall?
 
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Old 03-26-15, 03:22 AM
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If the exterior insulated walls have vertical stud framing, your finish can be applied directly to the studs over the vapor barrier. Any divider walls can be attached to the existing framing and top/bottom plate set up. I am concerned, too with the OSB directly over the concrete. Is this below grade or on a high rise? I see galvanized framing with screws in the OSB, which would be out of the ordinary for direct concrete installation. Is there any way you can confirm the OSB installation on concrete?
 
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Old 03-26-15, 09:54 AM
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Thanks Chandler ~

I just confirmed that the OSB is not in contact with the concrete. There appears to be steel framing below the OSB, which is separated from direct contact with the ground:

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So it sounds like I can utilize the exterior walls which have vertical stud framing as-is. For the exterior walls which are insulated with the blanket insulation and have no vertical stud framing (picture below), I assume I just frame a wall a set number of inches inwards from the insulation, leaving a small air gap between the blanket insluation and the framing wall?

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Last edited by PJmax; 03-26-15 at 05:27 PM. Reason: reoriented top picture
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Old 03-26-15, 11:42 AM
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Is the blanket insulation against a below grade basement wall?

I regards to leaving a space between wall assemblies, like having a vapor barrier/insulation layer, then a gap, then another wall, you create an intermediate zone that is subject to air circulation and moisture transfer, the results of which are dependent upon inside and outside temperatures and humidity. In other words, it will work sometimes and grow mold other times.

Photo 3 on the BSD-103 link above nicknames the blanket as aka the diaper and lists some of the concerns if your installation is below grade.

Bud
 
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Old 03-26-15, 02:44 PM
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Thanks Bud ~ I read the article about "the diaper" and was praying that CO was dry enough for it to be sufficient -- I'm questioning the budget available to replace/redo the insulation, although I haven't investigated how much a job like that would cost.

To answer your question, it is indeed below-grade.

If I were to leave the insulation in-place, is there any way to avoid that extra gap? Or is that simply an inevitability of framing along-side/adjacent-to the blanket?
 
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Old 03-26-15, 05:19 PM
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I can only take a stab at this, but a gap that allows warm inside air to seep in at the top while the cooler air next to the vapor barrier falls and leaks back into the basement places warm humid air next to the cold plastic vapor barrier. Air sealing the new wall and not going crazy with additional insulation may help. If you were to add r-19 in your new wall, then the surface of the encapsulated insulation would be colder than if less insulation were used. Right now that surface stays nice and warm so no condensation.

As for behind the plastic blanket, being a 100% vapor barrier, the moisture level between the blanket and the concrete will equalize to match the moisture against the outside of the foundation. The idea behind "no vapor barrier below grade" is to allow the moisture that slowly diffuses through to harmlessly evaporate and be dealt with on the inside. With a 100% vapor barrier, even with a vary slow migration of moisture it will eventually accumulate to be as wet on the inside as it is on the outside. Here in Maine, that is very wet. Colorado, no idea.

If you build your new wall directly against the existing blanket and allow your batt insulation to fluff out against the high and low spots of the blanket it will probably be the best you can do.

Bud
 
 

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