How to fix crumbling mortar?

PetaRufo

Hi Community,

I have removed the floor tiles in our laundry and have discovered a 5cm thick morter bed. I chipped up an area to see how deep the morter was as you can see in one of the photos. 

The issue I have is I do not want to remove the entire 5cm morter bed but the edges are quite crumbly.

My question is, how do I repair the edges and what would I use to fill in the hole I chipped out to ensure my new tiles are placed on a sturdy base? The rest of the floor is quite good.

MitchellMc

Hi @PetaRufo,

The best approach would be to keep chipping back all the way until you reach solid, sound mortar. You don’t want to tile over anything that’s already loose or crumbly. Most of those crumbling edges look like they'll come right out with a few blows of a mini-sledge and masonry chisel. Once you’ve got a stable edge, you can use a self-levelling cement to rebuild those sections and re-establish the edges of the mortar bed. The same product can also be used to fill the hole you’ve already chipped out. This will give you a strong, smooth surface and ensure the mortar base is properly supported before you go ahead with laying the new tiles. 

Please let me know if you have any questions.

Mitchell