Not sure where they came up with the 26" door thing. Not in our world. That door and the glass panel above the pony wall would all be custom, and the door would not be less than 30". Who designed this? These things are generally determined in advance.

No way is the standard size 26" (unless this was 1920 when that's how they did things). Every one of our doors is custom. Standards are based on type of door (roller or hinged, thickness of glass, clearance when opened, etc). Most often we do 29-32", but again, many design and technical considerations. I assume you have a shower door contractor involved? Might want to talk with them as well.

Did you pay for custom sizes rather than stock? Did you pay for full waterproofing and not just the pan?

As Sophie alluded to there is apparently no waterproofing on the face of the cement board. How is this shower waterproofed? Cement board is not waterproof on its own.

Geesh.

Regardless check your design, what is a comfortable opening for you to get in and out - if the opening is 26 the glass door itself may be smaller depending on type you get - are you doing framed? frameless? pivot? is your door swinging in or out? if your design had measurements and the shower is not the way it was specified then the builder needs to fix it, if your design had no measurements then the builder did it his way... decide who is at fault - have it fixed to what you want otherwise you will not be happy when it is done. Also check what the minimum code in your state is for the door opening.

@ Addy T - since you did not give him the measurements and just a general idea and you are not happy then if possible just pay to have the wall cut down and a larger door installed - check the pricing of the glass & door if you leave it as is versus the cost to cut back pony wall and the wider door; keep us posted and you will sort it out.. I do like your layout.. edit.. after looking at your design i noticed that you only have the 'half wall' with the arrow pointing to the back where the seat is.. was your intention to have the entire 'front' of the shower glass? then point this out to your builder..

It sounds like they made up an arbitrary door width. Anything below 28" would be the exception not the rule. Call several glass companies and ask them what size doors they usually recommend. Then use that as your argument with the builder.

You can get pivot doors that open both ways. That allows you to swing the door in to let water drip inside the shower.

Shower door can swing out or in / out - cannot swing in only for safety reasons. shower door opening as per UPC code 2012 is 22" for egress / ingress... who is doing the glass? the builders vendor or your own?

Call your own shower glass vendor (or more than one) - tell them what you want and get a price from them / measure as it is now and as you would like it to be and get both costs from them including installation - do not go to the builders vendor as they may have an agreement - since your builder is using his own vendor he will get you the cheapest set up. Is it frameless? framed? I would ask builder for photos of what he is planning to install with the measurements and ask him for his price options to make the pony wall narrower with a larger door / opening - discuss with hubby what is the size you want the opening / door to be and work from there.. your builder will probably not give you the price of the glass unless your contract / estimate / bid states materials costs.. I am a plumber and we work on flat rate - we use standard items unless clients want something other and we price on flat rate not time / labor / materials... I am sure you are stressed right now.. it will all work out - if you can live with it the way it is then do so - if not make the changes :-)

Around here the glass companies won't give you a quote over the phone. They want to see the job. The only argument you need right now is the standard size of a shower door opening per several glass companies and the builder's explanation of why he used a much narrower door when you had so much room. When you get to the point of choosing the glass and the door, you need
to be more involved in those decisions--thickness of glass,
water--spotting treatment, etc.

I don't think it was a great design to start with. How are your going to sit on the bench and have the water spray 7' from the opposite wall?

Not a good design to begin with. And no design measurements, or real documentation. The 4K upgrade for custom glass is on you. And there is no waterproofing on the bench or walls as shown. With tile going on top of an unwaterproofed substrate.

When doing a 12K shower, you can’t afford to not get professional design help. And if you didn’t pay 12K just for that gym shower, then your contractor isn’t doing the things that need to be done. Like waterproofing correctly. Like a secondary water outlet at the bench. Like custom 1/2” starphire glass.

Our custom glass shower door is 28" and feels 'normal' to me. It looks like you have another door next to your shower door and I'm not sure how these two will work together. Are you planning on glass above the half wall? How will it be installed? I think you should have 2 or more local glass shops come out and give you options and prices. You mentioned your husband is a large guy -- that might be the reason to make the opening bigger.