I am in the process of framing up my basement and am trying to work out the best way to insulate.

When the house was built we had the concrete walls insulated with an R11 flame spread insulation. (fiberglass insulation with a fsk paper facing that is nailed directly to the poured concrete wall.

I intend to leave the existing insulation and frame in front of it and then blow in cellulose with one of the big box rental machines.

My 2 primary concerns are:

Whether or not cellulose should be in direct contact with the slab and very bottom of the foundation wall where the fiberglass does not cover.  (I plan to diy spray foam on the bottom plate and slab to prevent the cellulose from sitting on the floor)

and

Whether or not I should cut slits in the fsk paper to eliminate the middle of wall vapor barrier – I don’t believe a basement vapor barrier is reccomended in this region.

Our energy bills are low enough that I do not want to spend too much on insulation, but I feel it would be irresponsible to do nothing at all.  I have already insulated all the bandboards with compressed R30 behind 2 inch rigid foam which I feel was the weakest link in our insulation.

House has 10 thick poured concrete walls about 6′ below grade.  Mixed mid atlantic climate being in Maryland. Any other factors to consider?

Thanks for any advice.

Jeff