It’s actually not the shower floor, but a small raised platform to step into the shower tray, so it will still get showered on. Concrete base with old tile cement on it approx 1/2 metre square. Got 10 by 10 white travertine tiles to lay, the heavily pitted distressed type ones. What do I need to make it waterproof?

here

http://www.theunderfloorheatingstore.com/prowarm—waterproofing-products-211-c.asp

The sealing compound

(Although mine hasn’t actually been tested yet …. fingers crossed)

But not sure why you’d want to waterproof concrete … ?

Sorry, it’s probably not concrete block, maybe like a breeze block. Also the travertine tiles are very porus I’d assume?. I was thinking there might be a paint on sealant or something?

Yes, you will have to seal them, probably every 6 months.
There are 2 types of sealant, a spirit based one, and a water based one.
I think the spirit one is better, but that’s my opinion, yours may be different.

They crack really easily, and dent easily too – no high heels on them.
I wouldnt be using the pitted/distressed ones for that use, they’ll hold water in the depressions.
(I wouldnt use them at all for flooring, as I think they are too soft, but some people like them)

I’ve got some that aren’t pitted but they’re definitely still tumbled with no finish on them.
Probably not my brightest idea, but I wanted something off white, grippy, rustic

Just google Travertine sealer…there’s a whole host of products.

Does anyone know if you can put sealer on the base and dip the tiles in sealer or won’t the cement / grout stick to it?

Be aware that some seals can affect the slip resistance. Also note that the pits and troughs, depending on depth, will be a nightmare to keep clean.

The spirit one makes you see funny colours if insufficiently ventilated when applying..

My advice – don’t! Useless material for being waterproof.

If you insist on using them then the best way will be to use a tanking system below them.

We have a travertine floor, we just made sure the grout stuff underneath was waterproof. 7 years on no issues yet

As per the last 2 comments. If you need the floor waterproof then tank it underneath. You can try to seal Trav and porous stone but you’ll never 100% get them sealed in my experience.

Lithofin slate seal and HG impregnator are 2 products that seal stone well though and repel water.

I tiled our whole shower in honed and filled travertine, and its been good as gold.
Sealed with Lithofin which does a good job.
Mind you, I would only have done it with honed and filled so you don’t get the holes.
Tiled a shower with the tumbled travertine and all you do is seal the tiles first, then grout the entire face of the tiles which does fill the pitted areas.
Then seal again with at least two coats.