Ditch the curb, you don't need it, and roll into the wettest area of your home. And another misconception, drains don't have to be in the middle of the floor. Whether custom tile, insert or tub-to-shower conversion, you can have a shower with flush entrance. Water will not get everywhere and can be directed as desired by gravity or even sucked down the drain.
Bottom line, curbed showers are dinosaurs, and only present an accessibility challenge if you ever lose mobility for any reason (e.g. pregnancy) or tripping threat if you're not paying attention (e.g. children).
Account for all life circumstances and achieve maximum accessibility and convenience by planning a roll-in shower, or better yet, make the entire bathroom a wet area for even easier cleaning. Design a universal shower usable by anyone including the space for a potential care giver or parent assisting young children.
The absolute minimum shower space, whether insert or tile, is 36 inches by 36 inches and no more than a 1/2 inch curb if you must, beveled to provide a tiny "ramp". Ideally, you want a flush entry. I cannot overemphasize there's no need for the curb.
For a true roll-in shower, allow no less than 36 inches by 60 inches and ideally 42 inches by 60 inches, or better still, 48 inches by 60 inches. Also plan a seat or built-in bench inside the stall. Splurge on space to make your shower the most convenient and safe for lifetime use regardless of how life happens.
And about those drains, here's a picture of Quick Drain USA's Pro Line linear drain, also known as a channel drain. Would you have known it was a drain if I didn't point out?
Linear drains can be placed along any edge. Some pans under the floor even feature a pump to pull the water out, otherwise the floor is gently and unnoticeably sloped, a maximum of 1/8 inch per foot, and the water can be directed to a side or corner to feed water into the drain, just as with the traditional drain in the middle of the floor.
Finally, install anti-slip flooring, throughout the entire bathroom but particularly in the wet area, and for additional comfort, consider a low voltage, radiant heated shower floor!
As mentioned previously, block behind the whole wall, floor-to-ceiling, on all sides with 3/4 inch plywood or comparable backing to enable custom height adjustment in the future for safety bars, fixtures or seating if you're not already including.
Next I discuss one of the most misunderstood bathroom fixtures.
President Todd Hawkins preaches building science and Universal Design (UD) to teach the benefits of an efficient, convenient, comfortable and flexible Lifetime Home. Also follow him on Twitter @BuilderFish for short tips about how kid-friendly UD makes home life easier and more secure for any person of any age or ability.