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Question about some old tile adhesive

Would really appreciate if someone can help identify some adhesive under my bathroom wall tiles. Its black and foamy/spongy. I just want to know if this stuff is safe to remove.

Any help is really appreciated.
Thank you for reading.


6 Answers from MyBuilder Tilers

Best Answer

This black mold was formed from wet / moisture that probably got under the tiles because it was a cracked grout. Before laying new tiles, you should clean the substrate with an anti-molding agent, even out if necessary, use a waterproof membrane (or Wedi building boards, Aquapanel cement boards - they are for wet rooms), then good tile adhesive, good grout. In the corners, in the shower, near the sink and bathtub - sanitary silicone.


Answered 5th Sep 2019

It is ok to remove it is a flexible adhesive


Answered 5th Sep 2019

Hi yeah it's safe to remove yourself. I come across it a lot when removing tiles. It's a flexible adhesive.


Answered 5th Sep 2019

Looks like a ready mixed Flexible adhesive... Remember seeing similar stuff years ago..only a guess tho


Answered 5th Sep 2019

The adhesive is adhesive from a tub (ready mixed). The black stuff is mould which has been building up, because over time water has penetrated the wall tiles as they are porous. This causes the plaster board behind to become wet, and the more you use the bath or shower, doesn’t give the plaster board time to dry causing it to rot and mould behind the tile. The water always takes longer to dry at the bottom because this is we’re it holds the most water.
The area around the bath/shower should of been what we call ( tanked out). This is waterproof membrane applied to the walls before you start tiling. This stops any water damaging the walls behind the tiles.
It is ok to remove the mould off the walls, but make sure you wear a mask, goggles and gloves to scrape all the old adhesive and mould off. I would recommend replacing the old plaster board with new and then put a waterproof membrane straight onto the boards. Do not plaster as this will reduce the amount of weight you can put onto the walls if tiling again. Alternatively you can replace the boards with a cement board called Hardi baker board.
With all the mould, old boards removed and replaced, a waterproof membrane applied to walls. Then you will have walls that will last for a long time.


Answered 6th Sep 2019

Youre adhesive could be the old Bal flex ,which is a rubber crumb mixed with a latex liquid,this is safe to remove as its a cement based adhesive.


Answered 8th Sep 2019

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