# Insulating Basement Walls Question



## rhymlz (Feb 13, 2012)

Just to give you a little back story, I purchased my home with a Full finished basement and bath. I then noticed water that pouring in after big rain storms. I decided to rip out all walls and framing. My question is do I have to insulate basement walls that are below grade next to the foundation? I have been told that I should use R19. The thing is, using a 2x4 framing construction and due to the space I need to put the framing I cannot fit R19. Is this a problem? 

Thanks iN Advance


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## Windows on Wash (Aug 30, 2011)

Walls should be insulated.

Fiberglass is a horrible option for basements and there are countless threads in here discussing the different approaches to basement insulation.

Where is the home located?


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## rhymlz (Feb 13, 2012)

I'm in Northern NJ. I had just spoke with my towns building inspector about the Rim Joist area and Rigid foam. He couldnt understand why I would use the rigid and told me to just use Fiberglas Batts in that area. Since he was so against the Rigid in the joists I figured I he would not like Rigid on the walls either. He also said the Rim Joist needed to be R19, would that also apply to the walls?


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## rhymlz (Feb 13, 2012)

Is insulating the walls code or is it just a preferred?


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## Gary in WA (Mar 11, 2009)

Teach him, gently.... Rims expand/contract with the seasons and humidity; http://www.buildingscience.com/documents/insights/bsi-023-wood-is-good-but-strange/

Fiberglass is excellent for furnace filters because it filters dirt. Great for finding air leaks in the attic because air blows right through it: http://www.finehomebuilding.com/PDF/Free/021105092.pdf

Bad for rim insulation because air blows right through it to condense on the wood.....use foam board; http://www.buildingscience.com/docu...joist/files/bscinfo_408_critical_seal_rev.pdf

As per Code. Find the closest City near you below the map: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm

Find the requirements: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

R-10 in foamboard or R-13 in other. Without the foamboard, you may likely have problems. Notice the different applications of below-grade insulation and the problems with each; http://www.buildingscience.com/docu...merica-high-r-foundations-case-study-analysis

The basics in a nut-shell: http://www.buildingscience.com/documents/reports/rr-0202-basement-insulation-systems

Of course, local AHJ have the final say.......

Gary


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## rhymlz (Feb 13, 2012)

If I put up 1" of xps can fiberglas touch it?


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## cibula11 (Jan 6, 2007)

spray foam and forget all of it....probably worth the effort of cutting precise pieces of foam board.


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## Gary in WA (Mar 11, 2009)

It should touch the foamboard: http://joneakes.com/jons-fixit-database/743

Air gaps will give convective loops.

Gary


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