What you might do instead is go with a premade niche. Then you don't have to worry about attaching anything to the backside of your siding. I've got a link below to some premade niches. As for the insulation, that's a whole other story, and I'll usually discourage the use of a niche if that's the only place to put one, only because even if the rest of the wall gets insulated, there won't be that much insulation, if any, between the back of the niche and the great outdoors, which, if you're in a northern area, can make for some pretty cold showers!! You could always use a couple of corner shelves, instead, but then again, it wouldn't be the first time I was asked to go ahead anyway and install the niche on an exterior wall. Matter of fact, I'll be installing one this week. :-)

Here is a link that might be useful: Recess-it

Could you not glue the cement board on with heavy duty industrial type glue? As to insulation I have a niche in my kitchen over my cooktop on an outside wall - maybe 8" x 12" in size. I live in Zone 7b so similar temps to you, there is no insulation behind the niche and the exterior is stucco. I have my OO there and it doesn't go cloudy as 'cold oils' are wont to do nor do I notice any coldness from this area. And its on a north wall.

I'm thinking you needn't be overly concerned even in a bathroom unless it's a very large niche perhaps. The heat of the shower water will nullify (at least in my mind) any concerns re: chill.

Let me know if it works out should you go ahead with it. If it doesn't work then I won't do it when I reno our bath. LOL!!

Could you not glue the cement board on with heavy duty industrial type glue?

Not safely.

As for the kitchen niche, you also have a source of heat right there that's usually energized when you're near it. As for the heat of the water vs. the cold coming from a bathroom niche, that's fine for while the water's running. But immediately afterward, it can get chilly pretty quick, not to mention the other times you use the bathroom without running the shower. This really isn't a good idea.

Hey Bill,

Thanks for the replies even though it's not what I wanted to hear.

I have a fairly small bathroom and after putting in a 5' tub I'll have room for a shower that is 3'x3'9" and I want to use every inch I have so I want to do a niche. Plus I like the look better than shelves, but if a niche doesn't work out I will go ahead and use shelves.

My other niche option though would be to put one (or two) on the same wall as the faucet/shower head (front wall).

I see two options:
1 - two smallish (width-wise) niches on each side of the front wall with enough room in between for the water pipe and framing on either side of it. So of the three feet width of the shower there would be a couple inches of tile, a 12" niche, a few more inches of tile, a second 12" niche, and then a few inches of tile.

2 - route the pipe for the shower head to the side of the shower wall, then back up and over to the center above one larger niche. The pipe in this case would make a U on it's side. So, in the middle of the shower wall there would be the faucets, above that there would be a 24" wide niche, and above that would be the shower head.

Do you Bill, or anyone else, have any thoughts about these option?

Thanks,

Okay-- one thing you want to keep in mind is that being there's a flange on premade niches, you don't want them too close to any corner, so that more than half the piece of tile is sitting exclusively on the niche's flange. That's asking for trouble. Now, I don't know what the plumber might say, but I like your second idea. That's actually pretty innovative!! The niche stays relatively dry, being it doesn't get direct spray, and it's still immediately accessable, even with soap in your eyes! LOL I REALLY like your second idea, as a PRIMARY location, as opposed to "trying to make it work"!!

Hopefully, one of the plumbers in here will chime in, and it's no more of a problem than added cost. If it IS a problem, then there's another alternative, and that is that the niche doesn't necessarily have to be premade, and it also doesn't necessarily have to be 12" wide:

Hi Bill,

Thanks for responding again. I got sick shortly after posting early Wednesday and am just now back on line for the first time since then.

I LOVE the niche in your post above. It looks great in that location and has nice dimensions. Are the shelf and bottom made from tile, or from thicker stone?

I'm pretty sure we're going to go with option 2, which you liked. We're doing the whole job DIY. My husband has done enough plumbing, for us and family and friends, and says it will work. I've done a little of the actual plumbing work as he's watched, and I'm planning on doing the work on this job as well.

Ok, back to my niche - I'm planning on building it myself rather than using a pre-made one because of the limited sizes. I want it to be about 18" high because my shampoo bottle and conditioner comes in 16" high bottles (from Costco) and I don't want to change. I'm not sure of the width yet.

The part I'm not sure of here is how do I put and attach cement board on the back of the niche. I could put cement board on the entire opposite side of the wall (the not in the shower side of the wall), but I'm planning on painting that wall, so I'd probably put drywall over the cement board if I did that. What do you recommend. This is one of those things that I haven't seen pictures of, or if I have it was before I was this far in the thought process and I don't remember it.

Thanks again.
Alice