tile on concrete

[jocar]

If I lay tile on my concrete basement floor should I lay a membrane like ditra between the tile and the concrete floor.

[pushkins]

You don't have to, but it's a good thing to do. Not for the typical reason Ditra is used (over wood substrates to accommodate movement) but as an isolation membrane, the tile glue and concrete will move together so the bond will be strong but if a crack develops in the basement floor the ditra will compensate for it and not crack your tiles and or grout lines.
If the concrete has been down for a few years and you can see the cracks you could just use an isolation membrane over these cracks or control joints in the slab, it will be much cheaper to do it this way and the membrane is super easy to apply, simply clean the floor (which you should do anyway) apply the primer to the concrete with a roller, let it get sticky then remove the paper from the membrane and stick it down. You can tile immediately.

[jocar]

[QUOTE=pushkins;54412]You don't have to, but it's a good thing to do. Not for the typical reason Ditra is used (over wood substrates to accommodate movement) but as an isolation membrane, the tile glue and concrete will move together so the bond will be strong but if a crack develops in the basement floor the ditra will compensate for it and not crack your tiles and or grout lines.
If the concrete has been down for a few years and you can see the cracks you could just use an isolation membrane over these cracks or control joints in the slab, it will be much cheaper to do it this way and the membrane is super easy to apply, simply clean the floor (which you should do anyway) apply the primer to the concrete with a roller, let it get sticky then remove the paper from the membrane and stick it down. You can tile immediately.[/Q
Thank you Pushkins for the helpful information.