Do i need to waterproof floor in bathroom prior tiling??

Originally Posted by martyjames

I am about to reno my small bathroom in old federation home - it had a concrete floor with small 'mosaic' tiles on currently - about 30++ years old i would guess. The area ,not including where fitted bath tub is, is less than 2m by 2m. I am thinking to lay the new floor tiles on top of the old ones - is that ok? Also do i need to waterproof the floor (on top of existing tiles?) prior tiling.

Any other tips?

many thanks

Hi Marty,
First thing is to make sure the old tiles are secure, the two bob test, tapping each tile should give a solod sound, anthing that sould a bit looer or hollow should be removed.

Also note, Tiles and glue are porous.
To waterproof the wall the floor joint you need to remove some of the tiles. Problem being that if you only waterproof the wall floor joint moisture will run under the existing tiles and into the wall.
The other alternative is the leave all tiles in position but water the entire floor.

Good luck and fair winds.

Originally Posted by goldie1

What they said 30 + years old. There is probably not much holding those old mosaics down.

I would think about pulling them up. Try and remove a few to see how well they are stuck.

Are you doing the walls and is there a shower. If so you have to waterproof there as well.

They look more like '50s tiles and will be embedded in cement mortar so might be more like 60+ years old although there were some tiles like this still being used in the '60s and '70s! I doubt they will be drummy or even close to being loose and unlikely to get loose either. They generally need strong mechanical tools to remove so are a safe and solid sub-structure to simply waterproof over. Main things is to make sure they and the walls are cleaned so there are no adhesion issues with the waterproofing compound.

I beg to differ. I have recently finished renovating a bathroom with those exact mosaic and I can tell you removing them was a breeze even when they were not drummy at all.
If you want to do a good job, lift the hole lot including the bedding and go down to the concrete slab. Redo the bedding with correct levels, and once dry waterproof and tile. A bit more work but you will not regret it and no step up nor cutting doors.