floor sealer required before tiling porch?

[The Night Tripper]

Hi All My next project is tiling our front porch. This has a concrete floor; I don't know if it has a DPM. I have been reading up on preparation and testing whether there is a damp issue which will need to be treated.

Thee is currently some vinyl flooring thrown down there, and if I feel underneath it is *slightly* damp. This might indicate that the floor will need sealing beforehand (ugh, I'm hpoing not to do this).

However my feeling is that is is more likely due to condensation in the unheated porch, rather than damp coming through the floor.

Any thoughts on whether I should be cautious or bold in my approach to this? Recommendations for what product to use if I were to seal very welcome as well. The porch is about 5 sq.m. in area BTW.

Thanks a lot Jon N

[The Natural Philosopher]

tiles are their own water barrier.

Think swimming pool.

No need for a DPM.

[jkn]

Ah - good. That's what I was sort-of hoping.

Thanks Jon N

[Tim Watts]

If you rely on the tiles to block damp, *do* use a suitably rated powered cement based tile adhesive and powdered grout. Pre-mixed either is a lot less resistant to damp weakening it.

[jkn]

Yes, I was planning to use as good a quality adhesive and grout as possible.

Thanks J^n