Pro Form Niche Caution [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-28-2004, 01:20 PM
:bang: So we orderd our tile and our Pro Form Bonsal niches (two narrow niches for either side of the shower riser and one wide one for the side wall), framed out the shower and included blocking for the niches. Got the Durock in and am ready to start cutting. Whoa-Nelly!!!

The framing was done from a Noble Company brochure for the PF-305 and PF-304 ProForm(tm) products since the Bonsal PF-305 and PF-304 ProForm(tm) brochure didn't have the outside (back) dimensions. BIG MISTAKE. The Bonsal narrow combination niches (PF-305) were 2-1/2" wider than the Noble Co brochure, 9" overall. I can make it work on the one side but the other side has a water pipe coming right through the edge of the niche.

My question is whether anyone has 'modified' these niches to make them work in a given area. I'd like to take about 3/4" off it and leave it on the shower head wall. I really don't have another wall to put it on. I would use the same PolySeamSeal Pro Siliconized Acrylic Latex Caulk to re-join the niche after cutting the section out that I had planned on using to install the niches in the first place. Whadda you guys think? Smart or asking for trouble?


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08-28-2004, 01:45 PM
Can you use a sawsall to relieve the stud just a little?

08-28-2004, 01:59 PM
Sure, only need an 1/8 off the stud. It's the 3/4" copper pipe on the left of the left niche that's the problem. And with what I went through to get it there, I'm not going to start moving plumbing again.

PS - It's the wife's idea to put the small part of the niche at the top. She thought it made more sense that way.

08-28-2004, 02:36 PM
Hi Stachey.

Guess I don't understand the real problem....from the picture, looks like it fits in there just fine.

08-28-2004, 03:50 PM
Wrong side. The one on the right of the shower head does fit after I took out the blocking. There's a sister niche that will go on the left of the valve and the space from the center 2x to the left 2x is exactly 9", the outside of the niche box. It's the copper pipe right next to the left 2x that is causing problems.

Anyone have any experience cutting and re-gluing these things?

08-28-2004, 06:28 PM
I've never modified a bonsal niche before but have a few ideas on how to do it (I have worked with other extruded cellular foam products in the marine/boat industry).

What's the thickness of the niche sidewall?

And exactly how deep is it, i.e., how far back into the stud bay does it protrude?

08-28-2004, 07:24 PM
The narrow niche has 1-5/16" thick sidewalls, 7/8" thick top and bottom walls, 1/2" thick back and 1/2" front flange. The depth from the back of the front flange to the back of the back is 3-1/2" (also the depth of the niche on the inside). I have an extra 3/4" depth (4-1/4" overall) in the wall cavity since I furred out for the slab depression.

My idea was to cut the side away from the back panel and top and bottom and then remove about 3/4" from the width of the niche (back, top, bottom and shelf) and re-attach the side to the niche. I'd overlap the back panel, top and bottom over the side (side panel inset) so as to get a full glue bond (the 1-5/16" wide).

I'm not sure what type of glue/caulk/adhesive to use to put this back together. If you've worked with the material, maybe you can help. I was going to use a 100% silicone but am open to expert (or at least friendly) opinions.


08-28-2004, 07:57 PM
Without the benefit of actually being there to take in all relevant factors, my approach would be (two choices listed in order of personal preference).

Assumption: Your only clearance prob. is on the sides.

#1. Set up you table saw fence to rabbit 3/8” + 1/16” (7/16” total) from each recessed side. You’ll still have 7/8” side thickness left. Set saw depth to just kiss the inside lip. Measurements should be taken from the back just inside the lip since the cross sectional view looks like it tapers towards the back. Coat the sawn sides with either a roll-on membrane like Custom's Redguard (if you already have some) or a loose mix of thinset with tape. This coating is only to restore some lost strength. Closed cellular foam is already “waterproof” and will continue to be so even after it’s sawn.

#2. Rip the entire unit in half (lengthwise) such that ¾” in total width is removed. Mount the two sawn halves together, the backs now, onto a scrap piece of plywood or CBU using a foam panel adhesive or thinset. Masking tape will help hold things together. Next day after that is set up, tape and thinset the inside cut seam. When dry add two coats of waterproofing membrane, Redguard for example.

08-28-2004, 08:29 PM

Are you saying that these rough-in dimensions from Nobel Company are wrong?

Pro Form Dimensional Details From Nobel (

08-28-2004, 10:48 PM
Yes, Mike, those are the dimensions that I framed to (understanding that the upper part of the narrow niche would not really be 12 x 12 but rather 5 x 12). My assumption (and we all know how to spell assume) was that since both Noble and Bonsal have a trademarked, coated foam niche, that they'd be the same. I haven't really seen a Noble niche, just the Bonsal "ProForm(tm)". Thus my original paragraph:
The framing was done from a Noble Company brochure for the PF-305 and PF-304 ProForm(tm) products since the Bonsal PF-305 and PF-304 ProForm(tm) brochure didn't have the outside (back) dimensions. BIG MISTAKE. The Bonsal narrow combination niches (PF-305) were 2-1/2" wider than the Noble Co brochure, 9" overall. I can make it work on the one side but the other side has a water pipe coming right through the edge of the niche..

I like the idea of just shaving the thickness of the sides, since it retains the integrity of the box. My original framing had 2x4's all around, so I'm not really concerned with a little lost thickness. It'll be getting caulked to the studs on the sides, top and bottom. The alignment with the shower head can be adjusted so that the tiles work out also. I had thought about cutting one side 3/4" but never considered cutting 2 sides 3/8". And I'm an architectural woodwork detailer.

I prefer that method to slicing the entire box just because, once you cut through the closed-cell foam, it's not closed anymore. It would also change the size of the niche compared to its sister.

Thanks alot, Mike.
I'll get some pic's up when we get that far.

08-28-2004, 11:31 PM
I'm glad that will work for you Stachey. On the left side of the niche, you may not even have to rabbit full depth, just enough to clear that pipe.

And by all means yes, pichers. Pichers along the way and pichers when your all done. I can't believe it....100% Yankee, been here for a year and I'm already talkin like a Texan. :D

08-29-2004, 06:10 AM
Sorry I am late to this. I have 3 Noble niches and all were just a hair wider than my stud cavity. Go get your self a 4" angle grinder with a 36 grit sanding disc and sand away some of the studs. You will be fine. I sanded about 1/8" on both studs to get them to fit nice and easy.

08-29-2004, 10:01 AM
I think you should hurry to get your job done so when you have visitors there aren't 4 people trying to share 1 bathroom.

Your son,

08-29-2004, 10:16 AM

08-29-2004, 04:34 PM
I cut the niche with a hand saw, gave me more control. I took off the 3/8 from one whole side (against the 2x) and then marked out the cut from the other side, just deep enough to clear the pipe. Now that my walls are set, I can do my preslope and liner and start on the durock.

Thanks again.

John Bridge
08-29-2004, 05:28 PM
Tell 'im, Scott. Quit screwing around with details and get the shower operational. :D

Kidding, of course.

I would like to clarify something about the difference between Bonzal and Noble Company. Two different outfits, two different products. The Pro-Form inventor, Dale Watnee, currently markets through Noble Company. The Bonzal products are made by someone else. There is litigation involved, but they are not the same products. Since I am friendly with both companies, I'm not choosing sides. That's just how it is. ;)

10-23-2004, 09:01 AM
Stachey (or anyone), which brand did you purchace, exactly? I know you said Bonsal earlier, but your picture doesn't match the pictures in Bonsal's brochure. The edges in the Bonsal brochure look very rounded, whereas in your pics they look very angular & square (which is what I want). And of course, to better add to the confusion they use the exact same part numbers...

Also, what are they actually made of? The Noblecorp site says their pro-form niche is made of extruded polystyrene. AFAIK, polystyrene is styrofoam. However, the bonsal niche in this thread looks like concrete. Can anyone help here? Am I missing something?

10-23-2004, 01:50 PM

I have installed two of the Noble Corp niches and am very happy with them. The foam that they are made of seems different from styrofoam cup material. I think you need to contact Noble Corp or the gentleman that creates the product for Noble Dale Watnee.

John Bridge
10-23-2004, 05:18 PM
The Bonsal niches are coated over with a mesh and cement. The Noble Company niches are not coated, but they are carved, as it were, from solid hunks of foam. The foam is very tough stuff. Either product is excellent. Both are waterproof.

10-24-2004, 02:41 PM
Given that I need to trim 3/8" from each side (just like Stachey did), would one brand be any better than the other (not asking anyone to pick sides, just if one is better for trimming)? It sounds like the Noble niche might be better, since I won't be cutting into any waterproof coating, like I would if I used a Bonsal. I need to order ASAP, since my tile is just about in... ;)

Stachey (if you're still there), did you re-coat the cut rear surfaces of your niche, or did you just install them as-is after cutting?


10-24-2004, 03:58 PM
Thats good. I would have had to take eighth off your copper supply pipe to make up the difference. :dunce:

10-25-2004, 03:50 AM

Don't trim the niche, tirm the studs. In both of our bathrooms the niches wouldn't fit until I trimed some wood away. All I used was a small 4" grinder with sanding disk and went at it.

10-25-2004, 05:56 AM
The niches were Bonsal brand, as I stated in my first post, but I used the rough framing dimensions from the Noble catalogue. I used a hand saw to cut the sides of the back, just enough to clear the stud on one side (3/8" full depth) and the water pipe on the other (3/8" x 2" deep, see picture with one side cut and the other side marked out with cut-out area and dotted warning line for interior of niche). After the cut I DID NOT recoat the back area since it will not be subject to any moisture. The lip will be caulked to the visqueen barrier behind the Durock.

Since we have two bathrooms the project has been on hold since preparations for Frances began. Then Jeanne came and then my job took off and I've been working seven 12's per week since. Come mid-November I'll get a chance to work on it again.

10-25-2004, 08:33 AM
Thanks for the clarification, Stachey. I _did_ read your first post, I only asked because your picture didn't seem to match the picture in the Bonsal brochure - their pictures show the front edges very rounded. I guess they must've trimmed it themselves for the photos so they could put radius tiles on the niche in the picture. *shrug*

Peter - I can't trim the studs - they're _metal_!! Believe me, I wish I could trim them or move them...

10-25-2004, 09:16 AM
Just to make it clear-----NOBLE NICHES ARE THE SIZE WE SAY THEY ARE!!

Noble's rough in dimensions were used for Bonsal products..The name PRO FORM is not Bonsal's name.,and should not be used by them..And the problem is not with either Company's Niches..

Pro Form ,from Noble Co. is made from a soild core of EPS with a cementitious coating.

10-25-2004, 09:42 AM
No worries! I think the caution in the thread title was to warn that you can't use Noble's printed dimensions for a Bonsal product. Since then, we've more been discussing how to trim the various pre-formed niches due to space constraints. :)

Since you're here Eric, I wanted to ask the best way to affix the Noble niche to the wall. Should any screws be used, or does the noble sealant 150 act as an adhesive that simply glues the niche in place?

10-25-2004, 07:47 PM
I recommend a good grade of silicone or siliconized caulk to fasten my ProForm niches to studs and ajoining panels.
You need to use a caulk that has a low VOC content, liquid nail etc. are usually pretty high in VOCs and may present an interaction issue with the extruded polystene cores of my product.
All joints and seams can/should be treated as you would any joints between two panels/backerboards, tape and top with polymer modified thinsets.
The ProForm products are coated, with an elastomeric finish, to provide the best bonding surface for use of both modified and non-modifed thinsets.
Thank you for your interest is ProForm.
dale watnee

10-26-2004, 08:42 AM
John mentioned in another thread that he would use screws as well. For a niche the size of the one I ordered (PF-304), it seems like a good idea (I _will_ have framing around all four sides of the niche). Should I simply screw the niche in through the outer lip (or through the sides of the niche), or will the silicone caulk do a good enough job of holding it in? I don't mind a little overkill... ;)

10-26-2004, 09:30 AM
in most cases the Silicone or Noblesealant 150 alone is enough to hold it to the back ajoining wall and cross bracing ,but if you want to use a nail you may.

John Bridge
10-26-2004, 05:43 PM
". . . a nail" Eric, for Pete's sake, can the man use more than one nail? :D

03-05-2005, 06:01 PM
If the whole idea is to maintain a positive water barrier then why penetrate that barrier with a metal item that will rust out and leave a hole?

I used expensive silicone caulk and put a 3/4" bead on the back at the joint between the flange and body plus a little more on the flange. Whatever was left in the tube went onto the studs all around the sides of the niche cavity. It took some time to push the niches in so that they were flush with the Durock, but I've got time. And using that much caulk, they aren't coming out. They're securely fastened to the studs and have a complete seal with the visqueen around the niche cavity. The visqueen was also glued to the studs with a caulk adhesive.

No nails. Not unless you have some 4d stainless steel finish nails, and then, what support is a little nail going to give in a foam niche?