Does anyone have any experience with the transformation cost of rooms from “flooring” to tatamis in old houses?

Still searching for a house but I have decided I want all sleeping rooms to have tatamis instead of the usual “flooring”.

Problem is, some properties that might have great location/price might not have tatami rooms and I want to be ready when it happens.

Not talking about DIY btw. I’m planning to entrust the job to a professional.

Thanks! 🙏

by franckJPLF