Do You BackButter Your Tile?

Interesting video; tnx. The narrator did seem to have a bias favoring back-buttering. What this narrator did not discuss is how the substrate does or does not suck water out of the mix. The last substrate, a plastic or synthetic material, showed 100% bond adherence to the non-buttered tile.... and I'll guess that is because the synthetic substrate does not want to suck moisture out of the bond. And both techniques showed poor adherence over plywood.... probably because it sucks the moisture out of the compound a LOT.

OP, if you are going over concrete, the mix and the moisture are gonna be more key than the buttering technique...just my opinion. You ought to have a good firm floor to work over...let's hope!

FWIW..... I put down a moderate bunch of tile 30 years ago when I built our house. It went over cement backer in each case installed over a good, heavy wood floor system with less deflection than the allowed code maximums. No back-buttering, and very little wiggling the tiles in, just a firm press on each; made sure the set compound was adequately wet and the backer board wetted slightly before spreading the compound. After 30 years.. no cracks, no lifted tiles, no grout cracks, no releasing, nothing; both tile areas are in traffic areas. But I don't do this as a trade; if I did, I might back-butter to try to reduce the chances of call-backs.

IMHO, the real matters are firmness and stability of the substrate and the flooring under it, and the wetness to be sure the substrate does not suck out excess moisture and hurt the bond strength. As for end bond strength, it has to be 'good enough'. So that is probably why if you take care of the floor setup and mix, it can work adequately either way.

Someday I may do some facing rock in a cold climate (western WY).... that's gonna be interesting!