I appreciate all your help!

Hi Triet. I suggest you read this article here about porcelain tile for a garage floor. You need PEI 4 or 5 rated tiles. The thinset should be applied with a 1/2″ x 1/2″ notched trowel. Make sure to back butter the tiles as well. There should be no air gaps under the tile or at the edges. Use an epoxy type of grout. It will not stain.

A few questions
1. What PEI rating is recommended for garage tiles?

2. How thick for Thinset?
3. Can you add anything to grout to stop staining?

Hi Tang. Your best bet it to check the sales at your local home improvement centers. We hear many reports from our readers finding PEI 4 and 5 porcelain tiles for around $1 per square foot, sometimes a little less.

Interested in porcelain tiles with PEI rating 4 or 5. Any recommendations/leads?

Thanks,
Tang

Hi Sandra. Large cracks and crumbles does not sound good. We highly recommend that you first determine that the slab is sound before you do anything. If the cracks and crumbles run down to the ground in places, then all you will be doing is building up a floor surface on a poor foundation. This can lead to tiles cracking and a host of other issues. It’s going to require that you remove and chip away at all the loose materials until all that is remaining is solid concrete. Providing the remaining slab is sound, you will need to determine which polymer-modified concrete repair material you will need to use to fill in the voids. You can’t use regular cement. It does not adhere well and will eventually break loose. Ardex Americas is good product to source. It will require calling customer service and describing in detail the condition of the floor after you remove the all the loose materials. CTS products is another.