My daughter's late-1930s house has a woodblock floor in the hallway, which I believe to be oak. It's very stable, flat, and solid but in poor surface condition with many light gouges, heel marks, and scuffs.
She was originally thinking of sanding and sealing it but would now like to lay ceramic tiles. Would backing boards be necessary? The tiles are 9mm thick and I'd would have liked to keep the overall thickness to around 12mm to match the rooms off if possible.
