Tile on tile

[Barrysh]

Hi, I am going to my son's house for a weekend to retile part of his bathroom. As it's a couple of hundred miles away I don't really have the time to take the old tiles off. Is is necessary to prime the surface of the old tiles and if so could someone recommend a product. Think there is about 4 sq yds to do. Could I just scour the glazed surface with a wire brush in a drill or a sander. Really want to crack on when I get there not have to wait for primer to dry. Not looking for a professional job, just trying to tart up his first house on a budget. Thanks

[wine~o]

Tile on tile is not recommended, especially if the walls are plasterboard (the plasterboard may fail due the weight)

However if it is plaster on brick and you are sure you want to risk the chance of failure then you'll need more than a light abrade of the existing tiles. An old chisel or similar should be used to score the tiles thoroughly. No primer necessary but you must use a cement based adhesive (bagged) not a ready mixed adhesive (tubbed)'

Finally I'd strongly advise doing the job properly and removing the old tiles first. Your choice though.

[D215YQ]

Just out of interest why isn't it recommended if the substrate is solid?

There's loads of adhesive bags that boast it can be used to tile on tile. After 30 minutes of smashing with hammer and chisel on the final wall of my bathroom and removing half a tile I just tiled over them and that wall is flatter and took me about 20% time of the other walls where i smashed off the tiles and repaired the mortar and then tiled - wish I'd just tiled over them all (though admittedly this is tile mortared straight to brick so no plasterboard issues and with the effort required to (not) get them off I'm pretty sure they can hold the weight).

Also tiled my whole flat floor on to thermoplastic tiles (inch thick tiles with 4 inches of sand/crumbly mortar to reach the floor underneath) - have no idea how I would have levelled/prepped that - it took me about 2h to get the test tile up to find the never ending crumbly stuff below it!! Had some doubts about whether the standard adhesive would hold on the vinyl thermoplastic tile but a year later decided to remove an internal wall so had to take up the edge tiles and glad I only had to take up 4 tiles as they came up in tiny pieces they were stuck so well. That was with no prep of surface either other than to clean it.

Sure I had to cut a bit off the the doors as the level raised a bit but that was about 2 hours work for 5 doors which is absolutely nothing compared to relaying 95sq m of substrate! At the end of the day tiling over tile made a 95sq m job doable room by room whilst learning to tile for 600 quid materials, if I'd had to take the floor up it would have needed a skip, labour, prep and would have cost me probably 7 or 8k and been much messier.

[Barrysh]

Thanks for that. Makes sense. I always remember my first foreman saying Always employ a lazy man as he will find the easiest way to do it.