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rhymlz 02-13-2012 10:41 AM

Insulating Basement Walls Question
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

Windows on Wash 02-13-2012 10:53 AM

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?

rhymlz 02-13-2012 11:01 AM

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?

rhymlz 02-13-2012 11:01 AM

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

Gary in WA 02-13-2012 11:47 AM

Teach him, gently.... Rims expand/contract with the seasons and humidity;

Fiberglass is excellent for furnace filters because it filters dirt. Great for finding air leaks in the attic because air blows right through it:

Bad for rim insulation because air blows right through it to condense on the wood.....use foam board;

As per Code. Find the closest City near you below the map:

Find the requirements:

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;

The basics in a nut-shell:

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


rhymlz 02-17-2012 04:22 PM

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

cibula11 02-17-2012 06:36 PM

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

Gary in WA 02-17-2012 11:07 PM

It should touch the foamboard:

Air gaps will give convective loops.


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