Tiling over exstiting floor tiles.

[Mattstocker]

Hey I am thinking of tiling my hallway. Is it ok to tile over the original floor tiles? I think I read somewere you can as long as there firm. Is there any particular way of making sure there firm? Also what kind of primer would I need? Or is it best ripping them up? Thanks for any help.

 

[DAZB]

As long as the existing tiles are not loose or obviously unstable then tiling over the top is usually fine. You may want to prime them with a coat of diluted PVA to help adhesion.

 

[AdrianMealing]

As long as the existing tiles are not loose or obviously unstable then tiling over the top is usually fine. You may want to prime them with a coat of diluted PVA to help adhesion.

You sure about PVA, surely it depends on what primer the adhesive manufacturer recommends,

 

[DAZB]

I'm just recommending a good universal general primer. Obviously the tile adhesive manufacturer will recommend you purchase and use one of their products as a primer but it's only to generate a sale and in most cases it is no better or in some cases any different in performance than PVA. If the user has the budget to go with a named brand then that's their choice but in my experience PVA works well.

 

[Richard C]

Sorry DAZB but that’s extremely poor advice; you should NEVER use standard PVA on any tile base; it remains water soluble & if it gets wet, the tiles can float around or in the case of walls, fall off. If you need to prime (depending on tile base, tiles & addy manufacturer), always use a SBR or Acrylic primer.

I’ve done the odd wall when I’ve had no choice but would never recommend it on floors. Tiling over tiles is a total bodge & you should really take them up; if you’re laying large format tiles it can also give problems if the floor is not perfectly flat & just imagine how much of a problem the next poor sod is going to have getting them up. Is this a concrete floor or suspended timber? If it’s suspended timber I would not advise it at all.

If you must do it;
The tiles must be perfectly clean so wash with Sugar Soap. Glazed tiles can give real problems with adhesion & you will need a suitable flexible powder addy. Some mosaic adhesives are suitable but many aren’t for use on glazed surfaces & most manufacturers don’t recommend it. You will need a good bonding primer or make your own priming slurry. Use only quality trade materials, the DIY stuff is generally crap but it won’t stand any chance in this case.

Do it right & take them up.

 

[DAZB]

If you read my post Richard C I gave advice based on the OP's question which was could he tile over the existing if they were firm ? I said he could but would use a primer to help adhesion. I went on to say that if the budget allowed then the manufacturers product could be bought but , and here's the important bit, in my experience PVA works well. I have done it myself in 'dry' areas and the tiling is still perfect. You have a point regarding it's partially soluble state but remember we are talking about a hallway floor not a bathroom or wetroom so it is unlikey to get sufficiently wet enough.

 

[tictic]

If you read my post Richard C I gave advice based on the OP's question which was could he tile over the existing if they were firm ? I said he could but would use a primer to help adhesion. I went on to say that if the budget allowed then the manufacturers product could be bought but , and here's the important bit, in my experience PVA works well. I have done it myself in 'dry' areas and the tiling is still perfect. You have a point regarding it's partially soluble state but remember we are talking about a hallway floor not a bathroom or wetroom so it is unlikey to get sufficiently wet enough.

when you mix your adhesive...what will it be???.....ya guessed it..it will be wet..and then when you pour it over that pva"d floor then it will become live again....

so the adhesive will have a bit off a problem bonding to the subtrate..

 

[Richard C]

If you read my post Richard C I gave advice based on the OP's question which was could he tile over the existing if they were firm ? I said he could

I did read your post & also gave advice based on the OP’s question & also advised that he could; but also added it’s a total bodge, which it is. The only thing I totally disagree with you on is advising the use of PVA as a tile primer. No decent addy manufacturer will recommend standard PVA (in fact I believe the only one that does makes the bloody stuff); neither will any experienced/knowledgeable tiler. There are numerous papers/articles about the problems associated with using PVA when tiling & the best advice is not to use it at all. Never skimp on primer (if you need it), it’s a false economy to use cheap/incorrect/incompatible products, not only do you risk tile failure you will invalidate the manufacturers warranty.
A decent acrylic/SBR based primer is little if any more expensive than good quality PVA (which is an excellent & versatile product in many other applications) so best not to use it anywhere, even in dry areas. As tictic points out, it will re-emulsify & affect tile adhesion. I don’t disagree he will need a priming agent but using the wrong one will have the opposite effect & in the case of glazed tiles you will need a bonding agent, not just a primer.

I also said;

If you must do it;
The tiles must be perfectly clean so wash with Sugar Soap. Glazed tiles can give real problems with adhesion & you will need a suitable flexible powder addy. Some mosaic adhesives are suitable but many aren’t for use on glazed surfaces & most manufacturers don’t recommend it. You will need a good bonding primer or make your own priming slurry.