Do I need to remove all the old adhesive?

[dazzystar]

Hi All,

I need to stick down one tile in the bathroom that has come away from the floor due to a leak over time. The tile is around 250mm x 150mm and had around 10mm-15mm of rubber based adhesive from 30 years ago. I've managed, with a heat gun, to remove 90%-95% of it but a very thin layer, enough to cover the ridges on the back of the tile remains and will be impossible to remove. I'm sticking it back down on to marine ply using some ready made mapei bathroom tile adhesive and wanted to know if I need to 'score' the back of the tile to provide a 'key'? The new adhesive will need to be 10mm - 15mm thick in order to bring it up to the same level as the other floor tiles.

Cheers
Daz

 

[dazzystar]

I should add that apparently the Mapei Ultimate Showerproof ready made adhesive I have should not be more than 3mm thick. Well that's not going to work as it needs to be closer to 10mm. Am I going to have a problem and if so, what can I use instead?

 

[simplesteve]

You can’t use ready made adhesive, especially so to ‘floor tile bed thickness’.
You need to buy a bag of proper Flexible Tile Adhesive, which comes in a powder cement form.
As you’re only doing one tile, which I presume can be walked around for 24 hours, you don’t need to buy a Rapid set one - standard ( ‘slow set’ ) will be fine. ( cheaper, and a lower stress level for you)
Re the adhesive left on the tile:- if you’re confident it’s stuck solid you’ll be ok to use the adhesive above to go over it - use the ‘flat side’ of your trowel though to spread a thin coat on the back of the tile before you stick it into the 8/10/12 mm notch adhesive you have on the floor.
Two wee tips:
1. It’s a lot easier when doing a single tile repair to put slightly too much adhesive on, than not enough. With too much, you can squeeze it down, shuffle it, lightly stand on and it keep removing the excess adhesive that squeezes out with a damp sponge.
( if you’re ’under thickness’ then you have to try and lift the tile back out the hole - breaking that nice bond you’ve just made )

2. Buy a white adhesive if you’re using white grout, buy a grey adhesive ( which will be slightly cheaper) if you’re using any other colour of grout. Though you can ignore this tip if your cleaning is immaculate
Just take your time, and Good Luck

 

[dazzystar]

Thanks very much for the reply. Why can't I use the ready made adhesive?

I should add that the floor tile I need to re-do is in an area of the bathroom which won't be walked on. The tile adhesive also needs to stick a wall tile with a similar or even more adhesive thickness!

 

[simplesteve]

If you search, there are plenty of other posts on here explaining why you can’t use an air/evaporation drying adhesive that thick on the floor. ( basically, it will never dry)
If I’m reading correctly, and you’re really putting a bed of more than 10mm on a wall, then there’s something wrong somewhere !

 

[opps]

If you search, there are plenty of other posts on here explaining why you can’t use an air/evaporation drying adhesive that thick on the floor. ( basically, it will never dry)
If I’m reading correctly, and you’re really putting a bed of more than 10mm on a wall, then there’s something wrong somewhere !

As above, the premixed stuff dries via evaporation. The powdered based versions contain cement. If you were to mix sand and cement and leave it in a bucket of water, it would still go hard.

When fitting mirrors into tiled recesses, I use those suction cup thingies for glass.

Something like this

Minotaur Suction Pad

A safe and simple way to move smooth, non-porous sheet materials. With this double suction pad from Minotaur, a maximum lifting capacity of 50kg allows you to lift and shift heavy or awkward items with ease.• Vacuum suction lifter – lifting capacity of 50kg• Double pad – for smooth, non-porous...

www.toolstation.com

But they also do single versions.

 

[dazzystar]

If you search, there are plenty of other posts on here explaining why you can’t use an air/evaporation drying adhesive that thick on the floor. ( basically, it will never dry)
If I’m reading correctly, and you’re really putting a bed of more than 10mm on a wall, then there’s something wrong somewhere !

Here's a pic of the area. You'll see the wall needs a thicker coating!

 

[dazzystar]

I've ordered a bag of this:-

https://www.screwfix.com/p/mapei-wall-floor-rapid-set-flexible-tile-adhesive-grey-20kg/700ag#product_additional_details_container

 

[simplesteve]

Good on you for going for the RapidSet !
Your wall seems to missing something - like some plasterboard

 

[dazzystar]

There was no choice...Only thing they had in stock and I though it's only one tile. Even me should be able to fit it within 3 hours!

There's no plasterboard on that wall. Literally plaster / cement on brick then tiles as you can see but over the years of this dripping bath panel the hardwall or whatever the builders used crumbled away. Could I use this adhesive to fill up the gap? At least I could use up some more of the 20 Kg bag!