We just bought a 100+ year old house and am updating throughout. The floors were in terrible condition and were stripped down to the wooden plank subfloors which are in good condition. For most of the house, we plan to put 1/2" plywood directly over the plank subfloor and then new hardwood. For the hallway and kitchen, we will be replacing the hallway radiator with radiant floor heating (pipes) under the hallway and kitchen tile. We are concerned that the hallway and kitchen floors will be substantially higher than the new wooden floors and our contractor suggested removing the existing plank floors and placing the plywood directly onto the joists for the area under the tile to save some height rather than placing the plywood on the existing subfloor.

As plywood is not as sturdy as solid planks, we are wondering if this will have any effect on the structure of the house? We would appreciate any thoughts or feedback.

Also, we can't increase the height of the floor too much throughout the house as the electrical outlets are in the baseboards.