Hi there, first time posting.
I was inspecting a new (2021 build) condo today and found the tile guy had left the underside of the built-in corner seat (master shower) exposed. There’s also no grouting along the course of tiles where they meet this seat.
Has anyone else seen this?
Welcome to our forum Michael!..Enjoy and participate. 
Just narrate/report what you see and refer it out for correction, as needed, to prevent rotting seat support.
Looks like Schluter Kerdi membrane.
If so, they have install guidelines available for downloading.
Thank you, for the confirmation Dominic! I was on the Schluter page reading about it when your reply popped up.
Correction as needed, or if needed.
In this particular case adding caulk or grouting may not be the right solution, as the grout can’t prevent entry of water vapor from the showers but more grout could slow drying.
Think of the seat as a “roof” and ask if it’s built right to shed “rain”. Just swap the words “seat” and “shower” with “roof” and “rain”. Look up “drip edge” or “capillary break” as well. And be sure you know if it’s actually wood, or a composite rated for wet areas.
Your likely trouble is deeper, if water can get to wood, before hitting some form of membrane or shower pan.
its really not hurting anything. there are tons of unfinished items that you dont normally see.
Yes, I have seen unfinished work. Somethings are really simple, do not overthink. @lkage had it right.
Unfinished tile work in the shower observed. Recommend correction by a qualified contractor.
Precisely why I, typically, did not narrate a solution in the report…let the qualified professional decide the fix and then the monkey is off my back.
kerdi board is waterproof. If thats what it is, then there is no issue, it’s just considered a cosmetic issue (that nobody will see)
I would still recommend that joint be caulked to prevent moisture intrusion between the tile and substrate. (which may also be kerdi)
Caulk will last as long as caulk lasts, then likely never be replaced. A drip edge would keep water out of that area for the entire lifetime of the shower. The older solutions (e.g. drip edge) are often the ones that last…
