Tiling over tiles....

[ray316]

My bathroom wall has tiles already on and l would like to put larger tiles up, the tiles already on will make a right mess trying to get them off as l've already tried taking one off and the adhesive on the tiles are taking the chunks of wall off with it..
So can l tile on top of these tiles, if this is possible is normal tile adhesive ok and do l have to do any prep work to the exsisting tiles, also what adhesive is best.
One more question for you tile experts, on one of the walls l need to put up plasterboard on top of the tiles already up, can l put tile adhesive on the boards to set them to the tiles so l can tile on the plasterboard after or is there another adhesive l have to use or will one coat plaster do..
Is plasterboard ok or do l need to use a special board for this, as the tiling on the plasterboard will be over the bath..

 

[bookahandyman]

as long as your existing tiles are firmly fixed , which tehy sound like they are , then you can tile over them. firstly i would 'sugarsoap' them down, and then buy a 'gypsum primer' to put on the tiles. then use a suiatble adhesive that says on the tin that you can tile on tile with it.
as for the plasterboard i generally knock a few tiles off along top middle and bottom of wall to get a good bit of rough key for the adhesive to stick to. i use ' dry wall adhesive' for this dab it in the knocked off tiles area and some on the tiles and press on board firmly and ensure level/vertical.

plasterboard is fine as long as the groutingbis up to scratch and edges are sealed well.

 

[Richard C]

Tiling over existing tiles can only really be described as a bodge, it just makes things worse when either you or some other poor unsuspecting soul comes to renovate again. Circumstances can dictate otherwise but generally its best take them off & start again.

The tiles must be scrupulously clean & you need to be very selective about your choice of adhesive. BAL White Star is suitable but drying times will be much extended & you could have big problems getting large format tiles to stay in one place; alternatively you could use BAL Rapidset with Admix AD1 which will be better for large format tiles as it relies on chemical curing rather than moisture evaporation.

I would not recommend plasterboard of any sort in wet areas & you would be unwise to rely purely on drywall adhesive to hold the boards in place. Generally misunderstood is that unless it’s one of the very expensive epoxy products, waterproof adhesive & grout is only waterproof in the sense it won’t dissolve when wet, it will still absorb water & if this gets onto a plasterboard base, it’ll fall apart & take your tiles with it. Use a waterproof tile backer boards & in your case you need to mechanically fix them; tile straight onto that.

 

[ray316]

Can someone then tell me the best way to get the tiles off that are to the wall without making a right mess of the walls, or if l have no choice but to damage the walls to get the tiles off what is the best way. Chip at them with a bolster, smash the tiles with a lump hammer etc.
Also what is the best method of removing hardened adhesive off the walls.

 

[Richard C]

Can you confirm the tile base is render/plaster over brick/block & not plasterboard either over stud or dot & dab?

Don’t start smashing at the tiles with a lump hammer or you will damage/dislodge the render/plaster beneath & even more of it will end up on the floor. I use a lump hammer, wide bolster & narrow cold chisels, driving under the edge of the tile at a shallow angle to the wall to cause the least damage, chisel any lumps of addy off the wall in the same way; keep the chisels sharp. Some favour using an SDS breaker drill but IMO they are too harsh & in the wrong hands can cause a lot of damage to soft block walls & mortar joints.

It’s not difficult but does require a little practice & can be time consuming, you just have to accept whatever comes off will come off I’m afraid but it’s often an indication that the render/plaster base isn’t very well attached to the wall so it’s better off than on. Once you’ve got all the tiles off, it’s a question of assessing the best way forward for remedial work before re-tiling. If the damage isn’t too great, it’s quicker & easier to fill in the holes & level off using cement based tile adhesive as you can tile over it next day. If the damage is extensive & you go with a re-render then it will have to be left to dry out (up to 4 weeks) before tiling; you can use a proprietary quick set render but its quiet expensive. If the lot comes off & your back to brick/block & don’t have the time to wait you can dot & dab MR plaster board & mechanically fix tile backer board in the wet areas & tile directly over that.

 

[ray316]

If the lot comes off & your back to brick/block & don’t have the time to wait you can dot & dab MR plaster board & mechanically fix tile backer board in the wet areas & tile directly over that.
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Richard C. You say if the lot comes off to brick l can dot & dab MR plaster board & mechanically fix... What do you mean by mechanically fix.
Do you also mean in the wet area over the bath MR plaster board and tile backer board on this

 

[Richard C]

You can dot & dab MR plaster board generally onto almost all substrates but PB is not good in wet areas (inside shower enclosures & behind baths), here you should use waterproof tile backer boards. You cannot just rely on dot & dab adhesive for tile backer boards, they have to be mechanically fixed due to their weight. Some are designed for this & some aren’t (manufacturer recommends fixing to battens) but you don’t need to do this; you can still dot & dab the boards in place as long as you mechanically fix them to the wall after the adhesive has set; basically you screw fix them to the wall where the adhesive dabs are using frame screws. You don’t need to additionally fix PB over tile backer boards, just scrim tape the joints & tile direct.

 

[ray316]

ok this is what l intend to do and tell me if this is wrong.
Where tiles are on the bath wall l am going to put up 6 batons 18mmx38mm horizoncal , l will drill through the tile grout lines into the wall and plug and attach the batons .
l will then put up aquapanels to the batons with 32mm drywall screws, the aquapanel being 12.5mm and the baton being 18mm so the screws will go through the aquapanel,batons and 2mm into the grout.
Then tile onto the panals.. Does this sound ok.

One more question l'm interested to know, could l have used a tanking kit and plasterboard..

 

[TrumpersUnited]

Yes tank the PB in wet areas. MR PB can still break down in water.

or use 12mm Hardibacker on the walls which is fully water resisitant but you will still need to tank edges and joints.

 

[Richard C]

You could have used PB & tanked it but why bother, backer boards are more expensive but the cost of the tanking kit & time taken in applying it more or less evens out. How easy are the tiles to drill? You may be better fixing the backer boards directly onto the tiles rather than batten as I explained in my previous post.

or use 12mm Hardibacker on the walls which is fully water resisitant but you will still need to tank edges and joints.

You don’t really need to tank the joints & edges unless constructing a wet room; just tape & skim with tile adhesive immediately before you tile. Some seal between panels with silicone but I don’t, if you spread it around too much it can cause problems; not much sticks to silicone! Make sure the backer board joints don’t coincide with any tile grout lines.

 

[ray316]

You could have used pb & tanked it but why bother, backer boards are more expensive but the cost of the tanking kit & time taken in applying it more or less evens out. How easy are the tiles to drill? You may be better fixing the backer boards directly onto the tiles rather than batten as I explained in my previous post.

Richard c. The reason for using batons onto tiles for aqua boards is because the bath does not sit under the tiles left on. l have just taken off tiles on plasterboards to reveal these tiles that are left on and wondered why the previous person did this and now l now why, the bath is smaller in length and width by 20mm so they packed it out with plasterboard that had thick dot&dab adhesive onto tiles but l would rather put batons up to secure the aqua boards to so when l tile on the boards the whole lot does not come down ... Does this sound alright..

 

[Richard C]

Does this sound alright..

Sounds OK & as long as you have a reason for doing it, it's got to be right for you.

 

[ray316]

Richard C., put the aqua boards up and now ready for tiling. l have the aqua tape for the joints and since it's not got adhesive on the stick to boards what is the best way to put on and seal joints.
You also mentioned early in the thread to use either BAL Whitestar or BAL Rapidset with Admix AD1 where is the best place to get this and roughly how much does the stuff coat.
l went into B&Q today as l had seen buildfix Ultimate showerproof wall adhesive 15KG for £19.98 but they only have them at certain stores in the UK .
Remember l'm also tiling onto tiles on one wall and the buildfix stuff said it was ok for tile onto tile ...

 

[TrumpersUnited]

I wouldn't use a ready mixed adhesive in this situation as the adhesive will take to long to dry.

I would personally use a powdered adhesive like weber set plus or mapei P9. They don't require any additives for tile on tile.

 

[Richard C]

I just use plasterboard fibre reinforcing tape which I always have but just fill over the joints with flexible tile adhesive, bed the tape & smooth it over with a trowel & tile as normal; not sure if I’ve said already but don’t let the tile grout lines coincide with the board joints.

I would forget B&Q (trade centres); I’d heard they stock Mapei but on checking recently, this appears to be sold under the guise of “Buildfix” & the products on offer don’t seem to match the Mapei product range so not sure what’s going on there. I’m a BAL man myself, hence the recommendations but I would also go with the cement based addy to avoid problems with adhesion & long drying times, as I’ve already stated. Weber set plus or Mapei P9, good stuff also but I’ve no idea of suitability over tiles without checking or weather or not they need any additive. With regard to stockist, try local trade tile centres or you can get it on line subject to delivery charge; coverage will be around 0.3m/kilo for wet wall applications, 0.4m/kilo for dry wall.