Restoring an old pool and plan to tile the whole surface.

[Lzylizrd]

I have an old pool 1956' Concrete, plaster then Marcite then diamondbrite on tidal property.
I removed the diamondbrite, found loose plaster in sections of the floor.
Question: Do I need to remove all the plaster down to the concrete or can I patch with Mapei patch.
I plan to use masalastic to waterproof the pool.
My concern is will the patch under the waterproofing bond?

[PoolDoc]

That's a really ambitious project, for someone who's not already an experienced tile setter. In fact, I've found experienced tile setters often don't want to go near pools!.

I'd recommend some serious investigation of some commercial tile sites, and then some long conversations with their tech people . . . if they're willing to talk to you.

People who are experienced -- and skilled -- in tiling entire pools are rare. It's pretty high end stuff, and requires some serious skill and knowledge.

It's not something I can help you with.

I can offer one bit of advice that applies to painting, re-plastering, AND applying tile: no surface is better than what's under it. If you don't have a sound surface under your tile, you'll never have a good tile application!

[Lzylizrd]

Thanks for that, but my question is about the substrate.
Should I take the whole bottom down to the concrete or patch the loose areas I have removed.

[PoolDoc]

I can offer one bit of advice that applies to painting, re-plastering, AND applying tile: no surface is better than what's under it. If you don't have a sound surface under your tile, you'll never have a good tile application!

That sort of covers it.

Whether a sound subsurface requires removing everything or not can't be determined from here -- not even with photos! But, if you want to be 100% certain, then removing everything won't hurt.

The difficulty may come if you find rotten gunite under bad plaster. In many pools, you have to make choice between patching and complete replacement.