One flooring company said they would install an uncoupling membrane when installing tile over my 100-year-old basement laundry room's concrete floor. OIs there a good reason to do use a membrane?
It strikes me as overkill. There are no cracks in the concrete, and I believe the concrete has been there for a long time. Our floor is painted, and we have zero moisture escaping from below per the plastic bag test. There are control joints through the room and they are uneven height, though not cracked. They'll be using a paste (not a true leveling compound) to even out and flatten the area.