I have torn down an interior wall made of lightweight concrete at home and plan to rebuild part of the wall with studs and plasterboard. The lightweight concrete was built in a recess in the base plate (see image) and I think I should fill in the recess before installing the studs. Am I thinking correctly? And which product should I use for filling? It should be able to hold up to drilling to attach the sill later.
There are two water pipes running to a radiator through the future wall, should I stabilize these in some way? Any tips on how to do that?