Can I safely tile on a tappy concrete floor?

[Russ42]

I have extended the laundry on a concrete slab floor and have concreted the area which was not tiles previously to get it up to the same level as the tiles (I have scuffed the tiles with an angle grinder). One part of the new concrete is tappy. Can I safely tile on this section or should I remove the concrete and redo it with a bondcrete sealer?

[EricL]

Hi @Russ42

There is the possibility that an air bubble was trapped in the concrete while it was curing. It's often caused by poor settling and not enough checking. If during the years that you've walked on this particular part of the floor and no cracks or spider veins have formed does not guarantee a sound base for tiling. The consequences of this part of the floor failing mean that the tile at the top will either come off or crack along with the floor. In the interest of longevity and the fact that I'm paranoid about proper tiling, I recommend refinishing that particular area. It may be extra work for you, but at least you'll have peace of mind that the floor is solid.

Please keep us updated with your progress, we look forward to seeing the start of your tiling project.

If you need further assistance, please let us know.     

Eric

[Russ42]

The original floor is a solid garage floor so prob no bubbles. I think the tapping is because the new concrete didn't bond to the old. The new is 25mm thick. My decision is to do as you have said and jemmy up the tappy part and seal it well before re-concreting it. There is aggregate in the new so I thought someone may have put me out of my misery and said it will be OK......