You can tile over the current tiles, and as another tradesman has stated please check the tiles are sound and not loose as this would cause problems later. Should they be loose, remove these and level the hole/gap to match the existing tiles, either with bonding/tile adhesive.
For a better job, it is always better to remove the current tiles, however i would not recommend the removal if the wall is stud work with just plasterboard, as if they have been installed correctly you will find the plasterboard will come off with the tiles, this would then mean re-boarding the entire area.

yes you can but my advise for the sake of a couple of hours work i would remove the old ones i know sometimes people are worried what will happen to the wall when you remove them but everything can always be fixed if you do decide to tile over the old ones please make sure that you rough the old ones up with a piece of scratch paper then coat with pva so the tile adhesive has something to adher to i hope this helps

kind regards stuart

Don't do it you'll regret it....
Take them off,and do a proper job..

Do not use pva for heavens sake, that just puts a skin on the tiles, which aren't absorbent, you end up tiling on a skin of pva, pva is to prevent fast absorption, so saying use pva then wait 48 hrs to grout is a contradiction in terms, yes you can tile over tiles, done it on many occasions, never had a problem, as with any substrate, it's got to be sound, and things to take in to consideration.

If you want a quality finish then preparation is everything.

We refurb bathrooms & kitchens and never in 12 years have we tiled over tiles.

It is better to strip off the tiles and skim to ensure a fantastic finish

thanks

We would not advise But ;

The existing tiles must be soundly bonded to the walls. Obviously, no matter how well fixed the new tiles are, if the old tiles de-bond from the wall and fall off, then so will the new ones. Make sure the old tiles are well fixed.

检查的一种方法是轻拍它们。如果它听起来很空洞，那么它们可能没有很好地结合在一起。特别注意潮湿的地方，那里更容易出现问题。

The existing tiles need to be clean and free of grease or other contaminants which could affect the bond of the adhesive used for the new tiles.

Some backgrounds such as plaster and plasterboard have a recommended weight limit for a square unit of measurement. That means that for instance plasterboard will have a maximum weight of tiles or stone you can fix to it, which if surpassed may cause a structural failure.

This is unlikely to be a problem if both old and new tiles are smaller format, thinner tiles, but could be an issue if using large format, heavier tiles on top. It especially likely to be a problem with natural stone tiles which tend to be heavier due to their thickness.

Only certain tile adhesives are suitable for tile on tile. Check manufacturers instructions or with your tiler.

One last thing to consider is the aesthetics. Tile over tile can be noticeable around the perimeters of a room such as coving, door jambs, and especially if the room is only half tiled.

You can tile over tiles, with the right preparation, but I would never do this, the proper way is to strip right back to original wall finish.
Dont worry if you do pull a bit of plaster when stripping the tiles, as its easy enough to replace.
Tiling over tiles can make it awkward, ie extra thickness when tiling around shower fittings.
For the sake of a few hours work I would take them of.

I always advise not to tile on top of tiles can't guarantee that the tiles on the wall have been put on securely.Always better to strip the tiles off and either replasterboard the walls or skim coat to give a good surface to tile onto

you can if you score the tiles with a angle grinder and put a sealer coat of sbr on them and only if the existing tiles are firmly bedded on the wall and not loose

It is possible to tile over old tiles with several provisos- the old tiles nead to be sound and there should be no "boss" areas (tiles that are loose on the walls, will sound hollow when you knock them with your knuckles) They should be bonded with a PVA sealing agent. You should check that there is sufficient clearance round windows, doors etc and they should be cleaned of mould.
You should allow extra drying time for the adhesive (48 hrs +) as the grout may be stained as adhesive drys through it.
You may need to fit new door facings or pack the old ones out so the tiles do not project past them.
Good Luck-Charlie Gillespie

怎么会有人用聚乙烯醇做密封剂呢?
I have re-done 3 bathrooms recently, where builders had used PVA to prime the walls.They had saved few quid, but few weeks later they poor job was exposed.
如果你准备墙壁使用专业的MAPEI或戴克霍夫Sopro液体。这花费了一点，但给了一个保证的信心。
BTW.You can tile over tile technicaly ( using one of the Sopro range adhesive you can tile even on glass ) but there are reasons why not to.Most of them have already been mentioned.

yes you can tile over tiles...
brian

Yes you can...but would advise not to do it. Better to remove old tiles first and skim the walls. You are then not as reliant to follow previously tiled areas. Good Luck . Myles Ark Plumbing.

新瓷砖的类型和尺寸是什么?它们是重瓷器/石头之类的吗?
How do you know if the existing tiles are fitted correctly?
Can they take the weight of the new tiles on top? can the wall?
墙上已经铺了多少层瓷砖?

The correct way is to remove the existing tiles and make-good the walls ready for new tiling.

Martyn

say do a proper job and remove old you will have problems in the long run please please remove them a good job is a proper job

This would be the ultimate bodge.
Please do remove tiles, you will not save a penny.
If the walls de-face during removal then there never was a sufficient strength.
Re-plastering is easy and finish is not important.

Good luck.
Louis.

no way , waste of YOUR money strip back to wall as some have said , it does pay to do a proper jobby

good luck with it
PDQ

You can do tiling over the old tiles. Be sure the old tiles are sticked well, check the tiles and try to smash them at the cross lines, that will help the adhesive to stick well. Another thing is to prime the old tiles with a two components primer. This advise is for cases when can't rip off the old tiles for many reasons . All the best

Best to remove them as you never know the condition of those underneath

You can be there are few jobs where this would be advisable. We had one job, a conservatory, with high doors frames. This gaining the height wasn't an issue and was cheaper for the customer.

No the old tile should be removed.