Painted concrete on floor to be tiled with UFH - Tile Advice

[JON HUME]

hi all, advice needed please,
I have been asked to lay travertine in a kitchen on top of UFH.
I went to look at the job today and the floor is concrete and has been pained twice.
Do I need to try and remove the paint or can I key it before fixing insulation board etc?
Also would you level the floor before the insulation board as the floor is quite uneven?
Photos attached.
Any guidance much appreciated.
Thanks, Jon

 

[Flintstone]

I would want that removed, from my experience of garage floor paint, it doesn’t adhere all that well.

 

[Saphiretiler]

What are you using insulation boards for ? Yes would definitely be removing all of the paint

 

[Flintstone]

What are you using insulation boards for ? Yes would definitely be removing all of the paint

Do you not insulate before fitting ufh ?

 

[Matthew77]

I’d remove the paint if possible. Depending on how bad/uneven the floor is I might do some self levelling before installing the insulation boards but generally I lay the boards, install the heating element then self level over the heating element so unless the floor is really bad there’s not usually any need to self level before boarding, just self level over the heating wire that way you have a nice flat surface to tile onto and the heating element is embedded in the self leveller safely away from being damaged

 

[JON HUME]

Thanks all, what’s the best way to remove the paint if I have to? The entire large ground floor is open plan so I’d rather not cause a dust storm. Would keying the floor not work?

 

[Flintstone]

Heat gun and scraper etc might work

 

[Matthew77]

Thanks all, what’s the best way to remove the paint if I have to? The entire large ground floor is open plan so I’d rather not cause a dust storm. Would keying the floor not work?

That’s going to be a rubbish job either way. Ideally I’d want to hire/use a big floor sander attached to a vacume for that type of job, the same sort of thing you use to remove latenance off gypsum floors. In my time I’ve used 100mm blade scrapers and angle grinders in the past and it takes ages like that. Heat gun might work well but again will take ages on a big floor!

 

[Concrete guy]

That concrete looks textured, you'd need to grind the floor a few MM to successfully remove that. Even with PCD cup wheels which are designed for surface coating removal you'd be grinding the concrete and not just the surface coating.

Surely there's a primer of some sort that would provide a key/chemical barrier, then maybe a thin self leveller?

I'd be phoning a couple of adhesive manufacturers for advice of any sensible alternatives to surface removal. it would help if you could find out what paint it is (if that's known by the owners).

 

[JON HUME]

Thanks guys, I’ll drop Mapei technical an email and see if they have any suggestions. Never straight forward is it!!!

 

[GoneGuy]

@Mapei UK Marketing could you advise on this?

 

[JON HUME]

Mapei have recommended removal but also suggested that eco prim grip could be used but they cannot guarantee what will happen.

Mechanical removal it is, cheers chaps

 

[martin1c]

A concrete grinding disc along with a grinder shroud connected to a hoover will make short work of that. Yes, there will be a bit of dust but the hoover should catch at least 90% of it.