Epoxy grout is more difficult to install (time consuming) because it must be done in "batches" (it "sets up" very quickly). Stick by your decision re: epoxy. If a contractor doesn't have an installer familiar and experienced with the product keep looking.

I don't like using it either but I can and do, and in our world, if the client wants it (and it is a recommended product for the application and in accordance to standards), the client gets it. Agree with chiflipper, keep looking as an experienced Pro can work with it.

Thanks. We only have a few design-build firms to choose from (after narrowing down the ones in our area to the best few). So I don’t feel like it’s as easy as just crossing one off our list and finding another that does have a tile installer who uses epoxy. So I guess I’m hoping I can push back on our top firm and request that they use epoxy — but then I’m nervous that they aren’t experienced with it and it will be my fault if they do a bad job.

I think what we might be suggesting is that if the contractor's installer can't do epoxy it could be an indication of their overall experience in general. This would bring me pause and you may want to research the qualifications of the contractor's installer. Grout selection may not be your biggest concern.

Skip design build. Work with a designer first. They will have pre screened contacts that do the higher end work that you want.

Epoxy isn’t the pinnacle of a perfect tile job. Very often its not a good option. Sometimes it is a good option. It’s always the most expensive option. Spectralock is probably 9x the cost of standard grout. So is the labor. Just know what you’re getting into here by asking for the most expensive job possible.

A design build firm is at best for core/ shell issues. Not the grout in your bath. Kitchens. baths, should involve a certified designer for just those areas. Grout is the least of the issue.

I will say if this is the start of a relationship with a design / build firm IMO your insistance about grout at this stage would be a red flag for me to back away.In the grand scheme of things this would be far down my list of issues I would want dealt with.