Tile Over Existing Tiles - Tile Advice

[Paul Finn]

can't say I've ever been a big fan of tiling over existing tiles but if the customer needed a small downstairs toilet floor or something similar and were on a budget, then as long as current tiles we're firmly fixed and sound with no underling issues, then I've always agreed to do it using a flexible cement based adhesive or similar depending wether concrete or ply base, and tbh I've never had a come back although to be fair it's very few I've tiled this way. I'm a firm believer in "out with the old, inn with the new"

Here's where it gets tricky! Mapei themselves have been out, surveyed a job and told one of my customers that it would be fine to tile over existing using there adhesive.

I'm no technical adhesive expert or mathmatician, but I'm very aware that adhesive companies like to swerve from a guarantee on there adhesives.

So if Mapei have said it's ok using there products and I'm agreeing to do job to that spec, then where do I stand "if" any tiles ever pop up Due to no fault in installation?

Bearing in mind this is a 400m floor.

Do I need a Mapei rep to overlook the job for me?

As always, any help appreciated.

Thanks

 

[Qwerty]

400m2, personally I would walk away TBH. Even if you did get mapei out, I doubt they would guarantee any work as they only guarantee their products not anything else. To big a job to go wrong

 

[Paul Finn]

That's what I was thinking. I'm in a right pickle now :/

 

[Old Mod]

Must admit walking away from that would not be easy! Wouldn't a method statement from Mapei work?

 

[Paul Finn]

Yeah, I defiantly need to involve Mapei in some way to cover my own back. Fancy telling a customer that, shocking!

 

[Old Mod]

I've done a couple of jobs where I've brought in different tech departments for their guidance, and had their recommendations in writing and then carried on.
Must admit (touch wood!) so far so good! but actually reading this thread and seeing someone else go thro the process makes me wonder how much I could actually rely on their recommendation if things started to go wrong.
I didn't actually even consider the possibility that although they guarantee their products they weren't guaranteeing me! Haha
There's arrogance for you!

 

[Paul Finn]

Brilliant, that's what I'll aim for then, some kind of written statement off Mapei. Touch wood all goes to plan :/

 

[Old Mod]

It may well be a good idea to get opinions from others on here, others may have very different views or experiences. I'm sure getting something from Mapei up front in the mean time won't hurt tho.
Try asking any of the TTA members like @DavidHoweTiling I'm sure they may be able to give u a more considered opinion.

 

[Paul Finn]

Cheers for advise. I've just rang mapei and they will email me a document saying there happy for me to use that spec.

As long as I'm covered I'm happy

 

[stephenoneill]

If tiles ate sound. Wash.prime. slc.and your good to go .never had a problem .and here in france all tiling work carries a 10 year warranty.

 

[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!