This article and others that follow will be devoted to home repair and improvement dealing with different areas from roof to basement.
If you are going to re-do the bathroom floor – this means taking up your tile, sheet vinyl, or ceramic tile and underlayments you should make sure there are no signs of water damage to the subflooring and check to see if it is solid throughout. When laying down a new floor the main question is always can I lay tile over the existing floor or do I have to pick up the old one first? If the floor is level and sound you can usually just tile right over it with plastic or vinyl flooring, but keep in mind how much room you have for the bathroom door, door frame and wall molding (if any) you may have to open or close the door from time to time!
If the underlayment is solid but not quit level you can use leveling embossers (like mortar) to fill-in low spots to make a level surface, otherwise place a new underlayment over it, if you can. I have seen home owners doctor it up with thin plain wood strips dont do it! All materials must be water and moisture resistant as possible. Always use at least a 3ft level to insure surface is...