We’re putting in a new bathroom and reconfiguring the laundry area in the unfinished basement of our 1928 home in Minneapolis, MN.  The basement has bumpy block walls, and a a clean concrete slab.  I’m looking for a gut check on wall/floor insulation and transitions.  We have had no issues with water intrusion through the slab/walls even with the huge rains in Spring 2024.  A dehumidifier has been working well to reduce humidity in the summer.

The bathroom will have radiant heat, so we plan to install 1/2″ Go Board on the slab as a thermal break, then install DitraHeat (or other heating mat) and top with 1/2″ thick floor tile.  The total thickness will be about 1.5″.

On the bathroom all adjoining the basement block wall, we plan to install 1.5″ of board insulation, then a standard stud wall with batt insulation.  Should the stud wall be installed on top of the go board?  Or should the PT bottom plate be secured directly to the concrete?

Secondly, because of the floor thickness of the bathroom, the transition to the rest of the basement floor is pretty drastic.  So I’m considering partially finishing the basement with 3/4 or 1″ eps and 3/4″ plywood fastened with tap cons.  However, doing the entire basement is sort of outside the scope of our initial plans.  Does it make sense to insulate the basement walls in the bathroom/laundry area and then complete the flooring at a later time?  Or should we just make a big adjustment to the scope of our project to get everything insulated?