I got a walk-out basement with a rough-in washroom. I wonder if I should build a sub-floor for the bathtub or I can put it down on the concrete and frame it around.
The last time I finished a basement was 30 years ago, I do not remember I put a bathtub. I will appreciate any tips and info sources you could point me to.
You shouldn't need a sub-floor. A lot of Florida homes have the tub on slab. Some tubs will require a bed of mortar to seat but you'd have to go by the manufacturer recommendations. If you go to Kohler or American Standard websites you can look up the tubs and also find the installation instructions online.