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Perforate paper on insulation?


JoeTheZombie's Avatar
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03-30-07, 09:31 AM   #1  
Perforate paper on insulation?

I'm refinishing a basement. I hung 6 mil poly sheets on the dry fieldstone walls. I then placed 1" extruded foam insulation and taped all seams. Framing is right up next to the foam. I'm using paper backed insulation, paper to the room side. Do I perforate the paper? I don't want to cause a moisture trap between the paper and the foam.

 
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03-30-07, 09:38 AM   #2  
Yes, perforate the kraft paper (slice it with a utility knife works), or remove it completely. Usually fiberglass insulation is a no-no in basement walls because of possible condensation and mold issues. Sounds like the visqueen and foam insulation should have the vapor permeability and condensation temps under control.

 
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03-30-07, 09:58 AM   #3  
Well it's not too late to not use the fiberglass. What substitute should I use?

 
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03-30-07, 11:26 AM   #4  
Perforate paper on insulation?

You may have enough insulation. What is the the code or suggested amount for your area? Some northern areas only insulate the top half of the wall and others only suggest an R5.

Usually basements are over-insulated to where you can't save as much on energy as the insulation costs. Remember, you are insulating the interior from the soil which is not nearly the same the outside air and you have no infoltration loses.

Dick

 
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04-01-07, 07:31 AM   #5  
This property isn't subject to code or inspections as it is located on county property. Only the top 1.5ft is subject to outside air. The rest of the 8.5ft is all underground. I can see what you mean about not insulating the bottom portion of the wall. Earth makes a pretty good insulator.

What would be the safest (non-mold inducing) material to use on the upper 1.5ft that is exposed? And should I install blocking at the 1.5 mark?

 
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04-01-07, 07:45 AM   #6  
http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf

Take a few minutes and read this. Other organizations such as Building Sciences Corporation (BSC) and also the National Research Council of Canada (NRC) and the CMHC all have a fair amount of information on best practices for insulating North American basements.

 
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