Ceramic tiling over expansion joint

[SkyHook]

I have had a new room built about 3m X 8m. , on a concrete slab. I am going to lay ceramic floor tiles (I am an amateur, but have done this once before). There is an expansion joint in the slab about across the middle. There is already a hairline crack there.

I have been given two bits of advice so far:

1. Use a flexible adhesive under tiles, so any movement does not crack them

2. Make sure there that a join line between tiles coincides with the expansion joint in slab.

Does anyone have any opinions, or more advice?

Thanks

Mark

[Honorary Bloke]

I have had a new room built about 3m X 8m. , on a concrete slab. I am going to lay ceramic floor tiles (I am an amateur, but have done this once before). There is an expansion joint in the slab about across the middle. There is already a hairline crack there.

I have been given two bits of advice so far:

1. Use a flexible adhesive under tiles, so any movement does not crack them

2. Make sure there that a join line between tiles coincides with the expansion joint in slab.

Does anyone have any opinions, or more advice?

Thanks

Mark

First off, be glad there is a hairline crack there--it means the expansion joint did its job.

I don't like flex adhesive under floor tiles. I would use modified thinset or whatever the OZ equivalent is. But I would like to see an expansion membrane put over the crack (joint) to uncouple it slightly (isolate the joint) from the tiles. Ask your tile dealer.

It is nice if the join line coincides with the joint but that rarely works out in real life. If you can do it, good onya.

HTH

[SkyHook]

Thanks for the advice,Bob