Insulate top of basement footing?
We have removed the slab from our basement and will be adding sub-slab insulation before pouring new concrete. I would like to preserve as much ceiling height as possible while still having a dry and comfortable basement. There will be a layer of 2 3/8″ EPS (R-10) under the entire slab that is even with the top of the footing. A dimpled membrane will be placed on the interior concrete block walls and lapped over the top of the footing to direct any water to the interior drain tile. Concrete will be poured directly up against the the interior drainage membrane. The interior walls will have 4″ of EPS against the drainage membrane with a 2X4 wall built in front of the foam. The original plan was to place 1″ thick EPS on top of the 2 3/8″ EPS so that insulation was present on top of the footings. With this approach the height of the finished ceiling is going to be 7′ 4″. I could gain another 1″ by removing the top layer of insulation.
How important is it to have insulation on top of the footings with this design? I’d prefer to skip the 1″ EPS and save ceiling height. We have had previous humidity and mold issues. My primary goal with the insulation is to prevent any condensation, and subsequent mold, from forming on the floor. The footings protrude about 6″ from the block wall; my vertical insulation from the walls will be 4″ thick with the 2X4 wall in front of that; could I just put a 2″ thick X 3.5″ strip of EPS under the wall plate to provide some insulating value from above?
Thank you for any responses, I am located in St. Paul, MN.
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