My mate put down OBC boards before gluing down 20mm T&G Birch parquet. A year on it has a spring in it when walked over, I wonder whether the density of the substrate or humity has weakened the OBC. I reckon as long as your floorboards are stable, hardboard should be okay. I put 12mm plywood down, screw fixed to the existing boards at 300mm centres, principally because it was left in that state for over six months before I could afford the oak parquet. I reckon I’ll have surplus but won’t know until dining room is done.
I’ve also decided to tile the hallway onto 12mm marine ply, once ceiling and walls are restored, creating more surplus parquet.
I prefer your overcompensating subfloor, despite my mention of standard procedures up above. Around here on the prairies humidity isn't too much of a problem so I suppose that might be why the go to is hardboard over ply.
I really like your sketch!
My mate put down OBC boards before gluing down 20mm T&G Birch parquet. A year on it has a spring in it when walked over, I wonder whether the density of the substrate or humity has weakened the OBC. I reckon as long as your floorboards are stable, hardboard should be okay. I put 12mm plywood down, screw fixed to the existing boards at 300mm centres, principally because it was left in that state for over six months before I could afford the oak parquet. I reckon I’ll have surplus but won’t know until dining room is done.
I’ve also decided to tile the hallway onto 12mm marine ply, once ceiling and walls are restored, creating more surplus parquet.