You buy 2, and join them, cutting 1 to size. Kerdi band on all corners and joins, bonding it to the Kerdi walls and shower tray. This is basic Kerdi bath 101. Simple. Simple Simple. If your installer doesn’t understand how to work with Kerdi, you need a different installer. Future Help Disaster post in the making.

Better rethink the design to work with the space you have, instead of the imaginary space you dont have.

Option -Call these folks. They'll make whatever you need. Possibly save a few bucks.

https://builtwithfoam.com/

Thanks! I will check them out.

Please do. Paul is great at this!

Thank you so much!! I visited the website and think the foam extension along with the Kerdi band to connect it to the longer bench will work well!

I've never understood benches in showers. Tile in a toe hold for leg shaving and call it good please.

I did built-in tile benches topped with quartz in my previous house, when I remodeled 3 bathrooms. They look nice and are ok to sit on, but they are so hard and cold.

We built a house this past year and I went with large enough showers to allow space for free-standing teak benches.

I ordered one from DecoTeak to try out. Really like the design, more ergonomic for human bottoms, doesn't feel cold when used and is very solid/sturdy with adjustable feet. I will be ordering 2 more for the other showers. They have the lighter teak color too and many styles, sizes and heights. The one I got is 30" wide.

I have a lot of reasons for wanting a built in. I like to sit to wash my feet/shave and am planning to age in place. I had a teak stand-alone bench in another bathroom and it molded between the slats. I also like that it is easy to squeegee/clean built-ins.