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alecmcmahon 01-09-2012 01:41 PM

R-Value Thickness foam board in basement floors/walls
Getting around to finishing my basement, I had some water issues previously but solved them by installing an interior french drain ( weeping system ) in to my sump pump and new gutter system.

It's been about a 9-10 months since these were installed and my basement is nice and dry.

When it comes to insulation for the floors and walls i'd like to use rigid foam board. What thickness is recommended for the walls and floors?

Due to space, and ceiling height i'd like to use the " bare minimum "

Would 1" foam board under 1/2 plywood for the floors suffice?

and 1" or 1.5" on glued to the walls with 2x4s in front with fiberglass insulation in between the studs work?

Im in central NJ, east coast... temps range from about 10 degrees F to 110 degrees F


Gary in WA 01-09-2012 10:47 PM

Find your Zone in the charts below the map:

Find the wall/slab insulation requirements with the zone here;

Do you have any exterior below-grade rigid insulation existing?
Or under-slab insulation?


alecmcmahon 01-09-2012 10:55 PM

No current isulation. House was built in 1955. Cinderblock walls

Gary in WA 01-09-2012 11:04 PM

And what R-value is required for your location?


alecmcmahon 01-09-2012 11:16 PM

Zone 4. Looks like r13?

Beepster 01-10-2012 02:30 PM

What is your floor currently made up of? Concrete?

What do you plan to use as flooring? Carpet? Tile? Wood?


alecmcmahon 01-10-2012 02:38 PM

currently concrete.


1" ( or 1.5" ) rigid foam board


1/2" plywood


Laminate flooring

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