Install new hardwood floors over old?
We are remodeling a 1926 San Francisco Condominium in a building with 27 other units. The wood floors are shot. They are 3/8 inch thick 2 inch wide oak strips that don't have a subfloor directly underneath. I'm not sure how to explain the thin strips of wood and joists that they were nailed to - but this all sits on top of the sub floor and in between it is filled with mortar dust and horse hair. We have also determined that the condo unit beneath us has their electrical running on top of our sub floor and laying in the morter dust. Our contractor recommended that we do not disturb the under-mess and instead just lay a new floor on top of this. We are planning to lay a 1/2 inch thick new plywood subfloor over the old floor and then lay an unfinished 3/4 inch thick 3 inch wide white oak t&g floor on top of this. Will this work?