Was the subfloor wet looking up from the bottom?

So, you will see it all over this board - and any others - that grout is not water proofing. If it's leaking on the underside, it's not because of grout - it's because your floor pan/drain was poorly done.

The standard test of a floor pan - before tile and grout - is the flood test. In that, they block the drain and fill the pan up with water and let it sit for 24 hours. If it leaks water it doesn't pass. Again the grout has NOTHING to do with it leaking.

If it's leaking, you almost certainly will have to rip out and replace the shower. I'm sure it can wait until warmer weather, but it will eventually rot the floor.

If it's not leaking, fix your grout, and then figure out how to fix your exposed plumbing for real. Don't count on things not freezing in TX anymore. Just insulating the drain line is not a great fix because it will slow down the freezing - but not much.

BTW: So, that's not a great tile/grout job. On narrow grout lines you use un-sanded grout. On large grout lines you use sanded grout for strength. I suspect you have un-sanded grout on a big fat grout line.

I stay away from the ready to use grout - but a better tile person than me can comment on them. My preference has always been Mapi that you mix with a latex additive.

Subfloor was dry looking up from bottom. We used fusion pro single component grout. It is okay to use for the fat grout lines according to manufacturer.

Question: Who did the pan / tile work? Was that you, or someone else?

My fiancé and I did it. I know it looks wonky around the drain. We live and we learn that cutting teeny tiles with a dremmel is much harder than it looks.

The pan was a prefab with the orange waterproof membrane. Then seams along edges were taped with more orange membrane and a grey goop (maybe thin set?) then everything painted with red water sealant before mortaring tile in.

Pre fab pan, then a waterproof membrane (orange) then red guard? Oh boy, you may have a mess with too many different waterproofing systems and that may be adding to your issues down the road. What sort of prefab pan, as most are waterproof out of the box?

Thanks for the info: The answer is the same - if you are seeing water leaking from underneath (the subfloor is wet) - it will be a rip-out and replace of the shower. There's nothing you can do on the top surface to change that.

It sounds like the base is not leaking - so that's good.

If just the drain itself is leaking, that could possibly be repaired.

And I agree with Millworkman, you mixed waterproofing methods. You don't want t do that. The proof is in the results though.

Freezing temperatures and an improperly waterproofed moisture sandwich= failure.