[Gogar]

Originally Posted by A930Rocket

You must have an older house or a really nice house. For the last 40 years, most houses use (1) floor joists, (2) 3/4”+ decking of some kind such as plywood/OSB/etc. and (3) the finished floor such as tile/wood/carpet.

Your floor probably has has a OSB or plywood sub-floor laid on top of the old plank sub-floor

My 1928 home has the original 1x6" sub-floor and 2.25" red oak laid right on top of that for squeak-tastic fun all day long!