Tile Over Existing Tiles

[Paul Finn]

Ok, so I took advise and contacted Mapei, here's there reply. I'll feel much better sleeping now

Dear Mr Finn


************* has had an NBS Specification for this project (14/04/2015 NBS 433) out lining our recommendation for this project, which they should be able to provide you with.

However we can confirm that provided that the existing ceramic/porcelain tiles are suitably solid, sound and thoroughly cleaned and de-greased, they would need to be primed using Mapei Eco Prim Grip and the new tiles are to be bonded using Mapei Keraquick incorporating the Mapei Latexplus additive.


Any lose or damaged tiles are removed and the area suitably repaired before tiling.


We hope that this information is of benefit to you and if you require any further assistance please do not hesitate to contact us.

 

[Qwerty]

Looks like you got the reply you wanted. How are Mapei or yourself going to measure just how solid the existing tiles are fixed? I'm always curious how this is measured as it's the one unknown variable that I wouldn't be able to quantify or prove.

 

[Paul Finn]

That did cross my mind and tbh I have no answer Unless I pay a lad to tap over the whole of it with a toffee hammer :/ One of the exact reason I would have advised against laying over existing. I suppose the only assurance there is is that it's been down for 4 years with cars driving over it and in that time I'd assume that if there were any loose/hollow tiles then they would have shown themselves by now.

 

[Old Mod]

Can an engineer take random samples to test the integrity of the floor?
I realise this will be an added cost but surely the client would benefit from such a process, giving you both peace of mind.
If was the client I'd be more than happy to pay for this to guarantee as much as possible that the project wouldn't fail.
Surely the client must realise there is still an element of doubt as to whether this would be successful long-term, surely the client must realise there is still an element of doubt as to whether this would be successful long-term, after all the existing floor is still an unknown quantity.
You can only guarantee what's on top of the floor not what's beneath it.

 

[Paul Finn]

I completely agree with what your saying makes perfect sense and it's something I'll try to research later and bring point across to client. As I mentioned, if Mapei wouldn't have got there foot in the door first then I can assure you there's no way in a million years I'd be suggesting that spec due to area size and heavy traffic. It's a new ball game to me!

 

[Dave]

That response and specification from Mapei is to Basicly adhere the new tiles to the old , it does not in no way offer that the existing tiles are well adhered , after all your installation will only be as fixed as the first lot are .

IMHO mapei were wrong to spec the job without at least doing a Scmidt hammer test , there is also the issue when tiling over existing tiles on larger areas of expansion , you have the screed expansion , then the first layer of tiles and then adding another layer that will expand at differing rates.

If the floor has to be tiled over , then at least Ditra it IMO... Cutting the stress has to be a good thing .

 

[Dave]

Also , don't forget inserting your movement joints over the old ones and in door ways if necessary .

 

[Paul Finn]

Thanks David.

Mapei have made my life hell on this 1

 

[Dave]

No probs , let us know how you get on ..

 

[Rizzle from the Portizzle]

Ok, so I took advise and contacted Mapei, here's there reply. I'll feel much better sleeping now

Dear Mr Finn


************* has had an NBS Specification for this project (14/04/2015 NBS 433) out lining our recommendation for this project, which they should be able to provide you with.

However we can confirm that provided that the existing ceramic/porcelain tiles are suitably solid, sound and thoroughly cleaned and de-greased, they would need to be primed using Mapei Eco Prim Grip and the new tiles are to be bonded using Mapei Keraquick incorporating the Mapei Latexplus additive.


Any lose or damaged tiles are removed and the area suitably repaired before tiling.


We hope that this information is of benefit to you and if you require any further assistance please do not hesitate to contact us.

however we can confirm that provided that existing ceramic /porcelain tiles are suitably solid and sound? get out number 1 / and thoroughly cleaned get out number 2 /and de-greased get out number 3 .only you can guarantee your work there is NO adhesive company that will guarantee all of the above .so its always going to be down to you only
so is the floor sound
well get your self a a 3ft crow bar run it all over the floor the sound from solid to hollow will stand out thats your choice at the end of the day is it sound .should only take a couple of hours
chop a few random tiles out even if it sounds solid
tiling over tiles has been going on from the roman times so its not new
all the guarantee will be yours and yours only .

the only thing that will guarantee your work is your knowledge and experience
so its your call .