I think the reason this isn't normally done is due to waterproofing issues. Generally when you get a tile guy who knows what the heck they are doing to build a shower with a bench for you, they build the bench INSIDE the of the shower pan out of masonry (CMU most of the time) and it becomes like one big monolithic unit. If you are doing this with a shower base, you obviously can't do it that way.

That said, I had a similar condition, just not the neo-angle shaped shower base. I did not want to deal with 1) finding a competent tile guy who I trusted enough to build a second floor shower base for me after we gutted this bathroom due to a leak in the first place and 2) deal with having to clean grout in the shower base (in my experience it's the grungiest part of the shower) but I did want a bench.

What I did is probably not approved by all of the tile guys on john bridge, I'm not sure what the ones around here will think, but I think it will work. We basically built the bench out of regular 2x framing, sheathed it with 3/4" plywood and then 1/2" durock and then waterproofed the whole thing with Kerdi membrane. It's pretty much rock solid though. The bottom of the bench acts as the 4th wall, and then it turns back to make the bench and then continues upward. I don't have great pictures, but here's the best one I have:

I don't think this is a smart thing to do with anything other than kerdi for your waterproofing - the chances of a catastrophic failure are just too high. I think the big thing that tile guys might disapprove of is the potential lack of rigidity of the wood frame bench cracking the grout and/or tile. I don't know if this is an even bigger issue with larger tile, I'm sure someone will weigh on on it though. I just know the princess (moi) wanted what she wanted and this was the only way she could have it ;). We just overengineered the heck out of the bench.

BTW I saw a neo-angle shower with the bench at once side in a display at an Expo store once and I thought it was the nicest neo-angle shower I've ever seen.

The only thing I can recommend is using one of the "Better Bench" pieces that bolt to the wall. THen you don't have to worry about conflicts between the bench and shower pan, because the two never meet.

Here is a link that might be useful: Innovis Better Bench

But then you would have to have a custom shower pan that extends under the better bench, wouldn't you? You couldn't get a standard neo-angle shower plus the extra "elbow room" a bench at the side of a neo-angle shower would provide.

But then you would have to have a custom shower pan that extends under the better bench, wouldn't you?

Not at all. Look at the link. The bench has no interaction with the shower pan whatsoever. THey can be used with prefab or custom shower pans.

Thanks for the input!

kgwlisa, your bench is exactly what i was thinking of. It looks like your wall tile goes pretty much down to the floor of the base. The ones I've seen have a bit of a shoulder, so the tile sits up higher on the wall.

I probably didn't explain myself clearly in the beginning, but I'm looking to have a bit more elbow room in the shower than a 42" neo angle will provide, hence the idea to add a 12" bench along one of the "long" sides of the neo angle, which will basically give me 54x42 of shower area.

From the pic, it looks like the better bench product will mount on the wall, so if I use the 42" neo angle prefab base, I'd still have 42x42 of shower area.

I've been reading all the kerdi stuff - I may change my mind and have a 54x42 base built, kerdi the whole thing - and use the better bench to have my extra elbow room...

I looked at the link, the point is that you don't get any extra elbow room with a bench that overhangs your shower pan unless you get a larger shower pan, and a 42x42 neo-angle is not that big to begin with. I certainly wouldn't want to lose 12" down one side of it and bring it down to 30x42.

fluke, I know exactly what you were talking about because as I said, I've seen that shower setup before and it was nice. It's the only way I'd consider a neo-angle again (I had a smallish one in my old bathroom and just HATED it - though some people have rather large ones here that wouldn't be as bad as mine was). It really just felt like a much more luxurious shower.

My base is built a slightly different way than a lot of the stock ones you see. It's built from corian and has a 5" flange around the perimeter. You shim out your studs and put your cement board overlapping it rather than just having it come down to the tiny "lip" on top of the more traditional type of pans. I really preferred the look and needed a custom pan anyway but it was pricey enough without adding another 18" of length to it so I went with this solution. I also personally prefer the look of a grounded bench over a floating one but I suppose you'd get a little more foot room with a floating bench and a pan that passes under it too.

I've sat on that bench a couple of times and it did not appear to flex, did not crack any of the tile etcetc so I'm not really worried about it. I view it as no different than having a knee wall that a big heavy piece of glass sits on top of at one side of my shower.

In case anyone else is thinking of doing this, I spoke to folks at Royalstone and Transolid, and they both said that it was not a problem to build a bench on a side of the pan. You treat the part of the bench taht runs perpendicular to the pan like any other wall shower wall, and make sure that the bench is not supported in any way by the pan.