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5 BIG Shower Niche Install Mistakes to Avoid in your Shower Remodel

Broken horizontal niche illustration - SNIM post

Steve Gehrmann is a remodeling contractor (SKG Renovations) as well as a partner in Redblock Industries

It’s truly frightening how many shower niche install mistakes that can happen in a typical shower remodel, especially if your contractor is building you a custom shower niche.

But even if you are planning to go the much safer route and install a pre-manufactured tiling niche or finished niche, you still must adhere to a few rules and procedures.

Following this advice could save you the nightmare and expense of moisture and mold growth in your walls, and tearing out your dream shower to do the job correctly a second time.

This is Steve from SKG Renovations with a few tips you must know to avoid the 5 BIG shower niche install mistakes during your next shower remodel.

If you’ve not yet committed to a shower niche, check out my Complete Shower Niche Guide.

The 5 BIG Mistakes:

Don’t Skip the Waterproofing

Don’t Install a Retrofit Niche

Make Sure It Integrates with the Waterproofing Membrane

Don’t Compromise the Wall Structure

Don’t Install in an Outside Wall

Bonus Tip: Installing the Wrong Shower Niche Shelf

Don’t Skip the Waterproofing

A bathroom remodel contractor waterproofing a custom-made shower niche

If you plan to install a custom shower niche into your shower wall, and you want to avoid making one of the biggest shower niche install mistakes, you must make sure that you or your contractor doesn’t forget the waterproofing step.

When a custom niche is built well, it can look very sturdy, solid and deceptively waterproof. This is an assumption made far too often when shower niches are framed into the shower wall.

No matter how tight the joints may look in a newly constructed niche, they will not keep water from penetrating and running into the stud cavity if it is not properly waterproofed.

You may be thinking that a leak like this seems unlikely if the niche is properly tiled & grouted after construction, and you would be right… for awhile.

The constant water exposure and regular temperature changes makes the shower environment quite unforgiving. These environmental stresses cause all parts of the shower assembly to move slightly, mostly through expansion and contraction.

Without a waterproofing membrane, this movement almost always causes grout line cracking in your shower niche. It usually starts out as very fine cracks at the corners that can’t easily be seen. But even the smallest cracks will allow moisture to penetrate, moving easily through the backer board seams, to the framing beneath.

The rest you can imagine; moisture in the walls, which leads to mold, dry rot, etc.………. something you can easily avoid.

Whether you or your contractor uses a liquid or sheet style waterproofing membrane, it does not matter, as long as you don’t skip this important step during your next shower remodel!

More info on shower waterproofing: Shower Membrane Waterproofing – The Definitive Guide

Don’t Install a Retrofit Shower Niche

If you decide to install a pre-manufactured, or finished shower niche instead of a custom built one, you can avoid another shower niche install mistake by making sure that you never install a retrofit shower niche.

A retrofit niche is a product that is installed in the process of a new shower remodel project after the shower wall tile has already been installed and grouted.

During a complete shower wall reconstruction, the retrofit niche hole is cut out of the the tile backer board after it’s attached to the shower wall framing. The tile is then applied on the shower wall as usual, but the hole is left exposed so the retrofit shower niche can later be inserted into it.

The niche is placed into this hole, and the outer flange on the niche is pressed against the tile. A bead of silicon around its perimeter completes the installation.

It doesn’t take a waterproofing expert to see that this tiny silicon bead is the only defence against water running into the wall cavity. Does that sound sensible to you? If you said no, you would be correct.

It may seem like a slightly easier way of installing a shower niche, but it’s not really much easier than the membrane bonding finished shower niche products out there, and it violates the industries recommended “best practices”. It’s really not worth the risk.

Make sure it Integrates with the Waterproofing Membrane

N1014 partially mounted to show MBlock flange and membrane bonding

Image of Schluter Niche - Amazon affiliate link via popup
Schluter Kerdi Board 12″x20″ Shower Niche
Ad: The above image is an Affiliate link

To avoid this BIG shower niche install mistake, you must choose a shower niche with an integrated  waterproofing membrane bonding flange as seen in the two examples above.

The first niche shown is a finished shower niche. This niche is made from sheet stainless steel with a brushed finish so it does not require tiling.

The membrane bonding flange mounts on the backer board surface with screws, and the waterproofing membrane is attached to the top surface of this flange (as seen in the above image).

The other niche shown is a tileable foam shower niche that has a 1/2″ thick foam perimeter flange that also serves as a mounting flange and a membrane bonding flange similar to the stainless steel niche.

The difference is that this niche must be mounted on the framing instead of the backer board surface, so that it’s 1/2″ flange can be flush with the 1/2″ thick tile backer board that surrounds it.

These flanges are critically important to maintain the integrity of the shower wall waterproofing membrane.

See more info on shower waterproofing: Shower Membrane Waterproofing – The Definitive Guide

Don’t Compromise the Wall Structure

Another BIG one among shower niche install mistakes, is the construction of a custom horizontal tiled niche that compromises the structural integrity of the shower wall.

If you’re considering building / installing a niche in your new shower remodel project, you have likely seen many examples of this type of niche. These horizontal niches are the epitome of opulence, sometimes spanning the entire shower wall and offering a huge area for storage.

There is a way to install these shower niches correctly and safely, but unfortunately many contractors fail to accomplish this.

Long horizontal tiled niche - stock pic

Most horizontal niches are built into the back shower wall; usually the longest, and therefore, the most flexible wall in your shower surround.

Sometimes this is a bearing wall that the structural integrity of your home depends on, and sometimes it’s not. Either way, cutting a horizontal swath out the structural members of this wall to make room for a niche is a problem.

Most decent contractors will say that applying the correct structural framing around the niche will adequately fortify the structure. The problem is that these measures mostly address structural stresses applied from above, but do not often address the increased flexibility (reduction in rigidity) caused by cutting out the vertical framing.

The integrity of a tiled assembly requires significant rigidity in this wall to reduce the chance of grout cracking, tile delamination, and failure of the waterproofing membrane. Some contractors do not even install the minimal surrounding structure required, which profoundly compromises the wall’s structural rigidity.

Constructing a New Wall for your Niche

If your new horizontal niche will span more than a couple of wall studs, the safest way to build your shower niche into this wall is to construct a new wall adjacent to it, to contain the niche.

This new wall allows you to build / install your custom shower niche with only minimal support above the new niche opening because the entire wall is anchored to the stud wall behind it. Super solid, super rigid, and super safe, because the original wall structure remains completely intact.

Another huge benefit of this parallel wall design is that it basically gives you the green light to install your niche into an outside shower wall (see below for more details).

In my opinion, a typical structural header and jack stud assembly can still be acceptable in some circumstances if the wall is non-structural, but this assembly must be built flawlessly. Nothing is safer that the parallel wall design I mentioned above.

Talk to your contractor about it, because it’s extremely important that you avoid this huge shower niche install mistake.

Don’t Install in an Outside Wall

This installation is often a BIG shower niche install mistake because moisture can easily condense behind your niche if you don’t do this install correctly.

In general it’s always the best idea to mount / build your tiled or finished shower niche in a wall that is not an outside facing wall.

The problem is that the shower environment is a very moist one, and some of this moisture will always make it into the stud cavity through the wall tile, your tile backer board, and often through your tiled shower niche.

How much water vapor will move into the stud wall is entirely dependent on whether or not a waterproofing membrane has been installed on the shower wall and how well your shower niche resists moisture penetration.

The moisture permeability of your niche will vary greatly, depending on the type of shower niche you decide to build / install, and the waterproofing strategy, of course.

Worth the Risk?

With this moisture penetration problem in mind you can probably see why it’s risky to install your shower niche into an outside wall.

In most older homes, the stud cavity is only 3 1/2″ thick and the comfort of your home often depends on this space being filled with insulation.

Even in a relatively mild climate, the colder months can result in a vast difference in temperature from inside to outside. Only a small temperature differential can cause the moisture in this shower wall to condense on the inside of the wall.

Even without a shower niche, this can easily occur within a 3 1/2″ stud wall in the colder months, especially if there’s no waterproofing membrane on the shower wall. With a shower niche taking up most of the space in a 3 1/2″ stud cavity, moisture condensation in the wall cavity is virtually guaranteed if the temperature drops a few degrees outside compared to inside.

Of course, none of this will necessarily occur if the shower wall and niche are properly waterproofed, and there is enough space behind the shower niche for adequate insulation.

Needless to say, there is a complex series of factors to consider like stud wall thickness, local climate, waterproof integrity of your shower, and the quality and thickness of the wall insulation.

In other words, you should definitely ask a trusted local contractor before you decide to build a shower niche into an outside wall to avoid this potential shower niche install mistake.

Bonus Tip:

Don’t Install the Wrong Shower Niche Shelf

This may not be considered a BIG shower niche install mistake but as a shower remodel contractor I hear a lot of people express regret about choosing the wrong shelf option for their tiled niche.

Usually the cheapest shelf option is a tiled shelf constructed with wood framing (if a custom niche) or 2″ inch thick foam board (see below).

Schluter Kerdi Niche 12x20 with arrow pointing to shelf 150W
Image courtesy of Schluter Systems

This is often a the most regrettable shelf option because it’s difficult to clean (especially the corners), and the grout lines stain and get moldy.

Another alternative is the glass shelf. A bit more expensive for the material but it’s usually the “go to” shelf alternative for most tiled shower niches. These shelves are so popular because they’re subtle, modern looking, and considered attractive by most.

Custom built tiled shower niche, glass shelves, white metal edging
Image courtesy of SKG Renovations

However, many people complain that glass shelves are hard to keep clean and soap slips off too easily.

The most practical and coolest shower niche shelf in my opinion is the stainless steel shower niche shelf. In fact I thought it was so great that I decided to design one to meet my clients needs.

Image courtesy of Redblock Industries

If you’re interested in this shower niche shelf or all kinds of other shower shelves, you can check out my shower niche shelf post.

Wrap Up

Installing a shower niche can be a deceptively complicated and risky endeavour, but it is possible to avoid the 5 big shower niche install mistakes.

If you need help with shower niche placement and design feel free to check out my Shower Niche Planning, and 9 Great New Shower Shelf Options posts.

Good luck with your new shower remodel project, AND enjoy your new shower niche!

Please leave a comment below if you’d like to ask any specific questions about shower niche installation. I am happy to help!

This post is for information purposes only and should NOT be interpreted as professional advice. You should always consult a licensed local contractor before undertaking any remodelling work in your home. Click here for my full Personal / Professional Disclosure.

There are 67 comments on this post:

  1. Steves User Profile Image

    Hi Hyaleah,

    It sounds like you put a lot of time and effort into your shower remodel project, especially your niche.
    There’s nothing like the satisfaction of doing a job correctly! Am I right?


  2. Avatar photo

    I’m doing a shower at the moment. put up cement board and Regard to the ceiling. The niche was on the outside wall but I built a second wall against it to give me the depth of the niche without disturbing the existing outer wall insulation, except for where I added another 2×4 for the rear wall of the niche for added support. I ended up putting in additional studs in all the walls because the walls in this closet turned shower had the most impractical stud spacing, nothing below 18″ on center, some as high as 26″. Modern construction at it’s best. 🙁

  3. Steves User Profile Image

    Hi Shawn,

    Congrats! Sounds like it was a fun project.

    It’s great to hear that you were not deterred by the sometimes intimidating prospect of tackling your own bathroom remodel project. It seems like you also felt some pride and satisfaction from your accomplishment… as you should.

    I think it would be reasonable for you to ask them to replace the frameless glass panel and door if it bothers you. It seems like you’re being quite forgiving of the mistake that they made (I agree with your evaluation, btw).

    Enjoy your new bathroom!


  4. Avatar photo

    Hi Steve, Great advice to everyone. I recently remodelled my wife’s retreat bath using a Schluter pre-fabricated niche and it saved so much time and hassle. I saved and reglazed the tub and it looks (performs) wonderful. I spent 3 months doing the project, three different kinds of marble two fans (to exhaust better as she like it hot and uses lots of product). It’s was a perfect job except when the frameless glass was installed, the installers drilled the glass for the towel bar and handle at a whopping 56″ above the ground. The miscalculated using measurement for a walk in shower I believe, rather than glass on tub. They claim 56″ height is industry standard. I believe industry standard height is 44-48″? Also a number of the hinge screws were not flush but angled and they claimed it was to give it strength. I am an engineer and have never heard such a thing. Straight, flush screws are needed to keep the hinge from torquing the tile and screws. Their angled screws into marble caused the front edge of the hinge to pull away (walk back from the tile face). Other than that, it has been a fun project?

  5. Steves User Profile Image

    Hi Ruxandra,

    Thank you for your comment!

    I’m not sure I understand your situation exactly, but what matters most is the distance between the back of the niche and the outside wall sheeting. I would recommend at least 3 1/2″ of space behind the niche if you’re insulating the wall with fiberglass. If this gap is any smaller, you should surround the niche body with spray foam. This will improve the R-value behind the niche and reduce the chance of moisture reaching the niche.

    As for the niche itself… it sounds like your contractor is planning to install a retrofit niche. Because this niche is designed to be installed after tiling, the silicon bead become the only thing keeping moisture out of the stud wall. In my opinion, all niches should bond with the shower wall waterproofing membrane whether they’re finished stainless steel or prefab tiled. Just to be clear… it’s the type of niche that you have chosen to install that’s likely the problem, not your contractor’s installation strategy.

    As far as I am aware, the Redblock niche and the Easy Drain niche are the only stainless steel niches designed to bond with the shower wall waterproofing membrane. Without these options, you’re probably better off installing a regular tiled niche using something like Schluter Kerdi SN. At least with this type of install, you can waterproof the wall recess properly.

    Good luck with your project!


  6. Avatar photo

    Hi Steve, we are in the process of renovating our two bathrooms and are planning to install a shower niche in each.
    I was wondering two things:
    1) You mention that it’s NOT recommended to install it on an outside wall. In our case, there would be a good 6 inches distance between the shower wall and the rest of the bathroom wall that is facing outside. Does this change things or is the condensation problem still an issue regardless?
    2) Our contractor told us he plans to prep the hole for the niche, install the ceramic tiles, then as a last step, apply the niche on top and finish with a bead of silicon to waterproof it. If I understood your guidelines correctly, the niche should be installed first, made 100% waterproof (using membrane) and the ceramic tiles should come after. Not the other way around. Have I got this right?

  7. Steves User Profile Image

    Hi Karen,

    Thank you for your comment!

    If you have a standard 3 1/2″ stud framing in this outside wall, it’s very likely that there’s a condensation/mold problem behind the niche, regardless how well they waterproofed it. To test this, you can let the shower dry out for a few days and test that back of the niche with a good quality moisture meter. Other than tearing everything out, this is fairly reliable way to find out whether there’s condensation behind the niche.

    As for the tile/ tub margin… the best way is always to silicon this margin. Grouting this margin seems like a better idea to the average homeowner (and the novice pro) but this is always a bad idea because the tub and the shower wall assembly expand and contract at different rates so the grout will always crack and break away over time. An expansion/ contraction joint is required here and silicon serves this purpose well.

    However, you should pay attention to any cracks that may have occurred within the vertical grout lines above the H tub/tile margin. If there are hairline cracks here (there often are after the grout has broken away beneath) moisture can infiltrate and pool over the silicon bead. This can cause mold to grow here which is not disastrous but it doesn’t look very nice. A good grout sealer will help reduce this problem (Sealers Choice Gold by Custom Building Products).

    Good luck!


  8. Avatar photo

    Hi, Steve! What a wealth of information! Wish we would have known some of this 5 years ago when we had our bathrooms “professionally” remodeled. There were so many things done that we now realize were probably not done well/correctly. We had a niche installed (3-1/4 inches, 4″ with the listello) in an outside wall of a shower. We live in Missouri so we have hot summers and fairly cold winters. Besides this problem, the angle is terrible and things often slide off the shelf. How can we tell if there is a problem behind this niche? We wish we would have gone with an Onyx shower surround. Also, in the other bathroom, there was no caulk placed between the tub and the tile wall – it was only grouted. Now some of that grout has broken. The company that we are considering for the repairs plans to just caulk over the grout, including the space where the grout has broken out. Maybe this isn’t such a good idea? The bids that we have are from companies that specialize in grout repair.

  9. Steves User Profile Image

    Hi Kelly,

    I think your husband has the right idea.

    The safest solution would be a sheet of plate steel behind the entire niche. Most electrical & plumbing codes accept 16 gauge steel (1/16″) for protection plates, so that’s what I would suggest. You can get a piece of galvanized steel cut at any sheet steel supplier or fabricator in your area.

    The easiest option would be simply to install your shower niche below 3 feet. The chance of anybody screwing something into the wall below 3 feet are very low. Tenants will usually be hanging a picture or coat hanger; probably nothing below 4 feet in other words.

    Good Luck!


  10. Avatar photo

    Hi, Steve.

    If installing a shower niche on in interior wall, what do you suggest putting behind it to prevent someone from puncturing it from the other side? We are worried someone might decide to drill through it to hang something on the wall behind. Ideally, extending the stud greater than 4” would have been best, but it is a really small powder room with a closet being converted to a shower and every inch counts. It is a rental property and we could just warn tenants not to hang anything there, but in our experience that usually never ends well. Is there a protector you can buy to install on the back of the niche? My husband thinks we should have a piece of sheet metal cut and installed.

  11. Steves User Profile Image

    Hi Jamie,

    Thank you for your comment!

    You definitely need to do something about these problems areas to reduce the chance of moisture getting behind the tile.
    Unless there are large areas without any grout, silicon caulking would probably be your best option because it’s very difficult to get new grout to adhere to existing grout, First you should remove the remaining spacers and clean out these areas (and all other voids) as best as you can. Use a grout removal tool to help with this and to remove any loose bits of grout.
    After vacuuming out all the dust, you should let the wall dry for a couple of days (a heater blower unit would be great to speed things up) to make sure any moisture trapped behind the tiles dries out.
    Seal the grout (and the voids) thoroughly with a grout sealer like Sealer’s Choice Gold. Follow the directions to make sure it dries thoroughly. The sealer is super important to ensure you get a good bond between the old grout and the new caulking.
    Then apply silicon caulking (only 100% silicon) to fill the voids.

    Good luck!


  12. Avatar photo

    Hi I have a new build ( 2 years old). They didn’t fully grout so there was a few missed tile that they just caulked instead of re grouted should I be concerned? They also left some of the spacers in and grouted over them. Also, the door has a quartz lip where the quartz meets the tile and between the tile and quartz there is a hole and can see the water dripping off the bottom. They left it open meaning I can see through from the outside/inside of the shower and when getting down and looking at the quartz/tile junction. Should I be concerned of this as well?


  13. Steves User Profile Image

    Hi Shawn,

    Thank you for your comment!

    Your acrylic idea is interesting and it may work, but it would be a bit risky to ask your tile installer to cut and install this material since he/she has probably never handled this kind of material. Acrylic is also super soft. It will scratch and get foggy over time, and I would guess that harsh cleaners like bleach would accelerated this process.

    I am not surprised about the $1,200 quote. Some stone fabricators may help you out with a couple of easy cuts, but as soon as it’s perceived as a “job”, they will want to be paid well for it. The safest way to get a good deal on scraps is to buy them as is, and get your tile installer to cut it.

    You should also check your local tile store. You should be able to easily find a large format natural stone or quartz composite tile, 3/8″ to 1/2″ thick. And again, your tile installer would probably be happy to cut & polish the edges for your niche.

    Have fun with your project!


  14. Avatar photo

    Super helpful post! I like the Redblock corner shelf design; especially the fact that it doesn’t interfere with the waterproofing membrane and it’s a bit more transitional design than the Schluter option. One question regarding niche box and shelf components: what about the use of thinner (e.g. 1/2″ thick) acrylic solid surfacing materials? I just got a quote back for 2cm quartz pieces for a custom niche, and it was over $1,200! If a smaller sheet (perhaps remnant) could be purchased of 1/2″ thick solid surfacing material in a color very similar to the shower wall tile, wouldn’t a good tile setter be able to cut that to create the niche box (sides, bottom, top, shelf)? It isn’t going to be quite as stain and scratch-resistant as quartz, but I think it would be safe, waterproof, durable, and easy to clean (potentially even bleach-cleanable). You could still use the wall tile or an accent tile for the back wall of the niche. Thoughts? Concerns?

  15. Steves User Profile Image

    Hi Mona,

    Thank you for your comment, and I’m sorry to hear about your troubles with your niche install.

    I would suggest that you get rid of the niche if it’s already causing problems. After a shower wall is tiled, it’s too risky to attempt to repair or re-build a shower niche at this point.

    Your best bet it to remove some tile around the niche, open the wall, remove the niche, install some new bracing between the studs, insert insulation to re-fill the niche cavity, then patch the hole with a new piece of backer board (attached to the new bracing).

    After the board’s perimeter is patched, taped and sealed, they will need to apply a new piece of waterproofing membrane to cover the patch. Make sure the new membrane overlaps the old one by at least 2 inches. Then tile and grout!

    Good luck! I hope the repair works out.


  16. Avatar photo

    Hi there,

    I have a niche install on an outside wall and now is bad condensation, I have the builders coming back to rectify. But I would be grateful if you could let me know what would be the best way to do this? Both if we wanted to keep the niche? And if we wanted to block it up, what materials ways should this been done to ensure the integrity is restored?

    Many thanks

  17. Steves User Profile Image

    Hi Lydia,

    Thank you for your comment!

    If I understand you correctly, you have furred out the wall to create a ledge upon which you will affix a marble shelf. Assuming this is correct, I would suggest that you install the shelf before the tile. The general rule is to install the horizontal finished surfaces in the shower before the vertical. That goes for shower floor and wall tile but also stone shelves and ledges.

    Generally speaking, it’s not good to install the vertical tile (or stone) first because water that runs off the vertical tile surfaces could settle at the gap between the floor and wall tile. If the sealant is compromised here, water could recede into gaps with nowhere to drain. If horizontal tiles are installed first, the water would have to move upslope under the wall tile in order to make it to the wall, which is much less likely. This makes it a much safer install.

    You should also make sure the shelf is sloped slightly outwards. Your bar soap will probably slip off the shelf, but you don’t want water pooling at the base of the wall tiles regardless of how well you’ve sealed this margin.

    Bonus tips: Make sure you seal this shelf with a good grout/stone sealer. Marble can discolor quite easily if not sealed, but you should always keep it clean because sealers are not perfect (nor permanent).

    Good luck!


  18. Avatar photo

    Hello Steve,
    Really good article. In our new shower, we built a knee wall in front of an exterior wall to put a shelf on. My question is about the installation of that shelf. We want to use a single-piece of marble for the shelf. The wall behind is subway tile, and another accent tile to the left. Is it okay (or preferable) to install the shelf itself last, or should we install the shelf prior to tiling the surrounding walls?

  19. Avatar photo

    Hi Rich,

    Thanks for your comment! It’s always great to hear from a fellow contractor.

    Yes, I agree that the structure required for a horizontal shower niche is the same as what’s required for a window in an exterior wall.

    I think it’s great that you use rigid foam to insulate behind the niche because of its high R value. With 2×6 exterior wall framing, there’s always a bit of room for some insulation behind a typical shower niche install. It becomes a much bigger problem when the wall studs are 2×4.



  20. Avatar photo

    I’m a tile contractor. You can absolutely do this as the writer mentions if done correctly. I just did a 52″ linear niche in an exterior 2×4 stud wall cavity. It’s accomplished with framing protocols to comply with your local codes. Frame it like a window! Windows go in exterior walls so you treat your niche framing as you would a window going in. Run a 2×8 or 2×10 header, king stud jack stud, ledger and cripples. Behind the niche you waterproof the exterior wall board with red gard, then a thin later of insulation. All of our cavities we use 3 inches of foamular rigid foam board giving an r value of r15 before tiling. We use hydro ban and laticrete sealant and water proofing. We also ran lighting by philips Hue strips in the niche. It’s a rock solid installation with hydroban vapor and waterproofing barriers. Just remember…FRAME it like a window and waterproof!

  21. Avatar photo

    Hi Betty,

    Although your outside wall may not be subject to the same temperature changes as an exposed outside wall, foundation walls like this can be troublesome because of moisture. No matter how well sealed, every foundation wall will be relatively moist. The amount of moisture in this wall will determine your best move so you should really get a local expert to advise you.

    Regardless of the results, I would install another stud wall adjacent to your existing wall and insulate this wall. Depending on the degree of moisture, I may not insulate the existing wall so air can circulate between the shower wall and foundation wall.

    I would also suggest installing an extremely good sheet waterproofing membrane. See my waterproofing membrane post for more info.

    There is a lot more I could say on this, but I think you get the picture 🙂

    Good luck with your shower project!


  22. Avatar photo

    These are all so informative!

    I am in the midwest (St. Louis) and planning a shower niche in a basement bathroom on an outside wall that is completely underground as well as having a 6′ deep front porch beyond that so there will be no outside air hitting that wall at all. The wall is framed with metal studs and reinforced with wood and there will probably be some air circulation at the tops of the walls above the drywall ceiling into the joist area because the metal studs are not very air tight. The bathroom wall is 5′ long, and once you get past that, you are in an unfinished space next door.

    Can you tile right on the concrete wall, use the waterproofing membrane all around and have good results? It will be a single 30″ square niche.

  23. Steves User Profile Image

    Hi Janine,

    It depends a lot on how cold it gets in the garage but even if it doesn’t reach freezing temperature, moisture could still easily condense in the stud cavity. In other words, it’s very difficult to say for certain if it will work out well in the end, but there are ways to dramatically reduce the risk if you really want to build this niche.

    The most important part of this project will be your undertile waterproofing. I would suggest that you apply a VERY GOOD sheet waterproofing membrane, not a liquid membrane. You need a membrane with a very low perm rating like the Durock sheet membrane or Wedi Subliner Dry. This will reduce the amount of water vapor entering the wall to the bare minimum.

    Installing porcelain tile on the shower wall instead of ceramic with a sealed grout like Mapei Flexcolor CQ, will also greatly reduce vapor transmission into the wall.

    Thirdly, I would insulate with spray foam if possible. Foam board is not ideal because it is important to fill the entire cavity behind the niche with insulation (no voids). It would be great if you could fur out that wall to make it a bit thicker. This would allow you to add a bit more insulation behind the niche, but either way you should use spray foam because it has a greater R-value per inch of thickness.

    It would also be important for you to remove the vapor retarder plastic sheet in this wall. This sheet will only provide a condensation surface for moisture. Best to get rid of it.

    Lastly, I also have to warn you about the risks of installing a long horizontal niche. I suggest that you please re-read that section of my 5BSNIM post so you are aware of the risks, and the additional structure required for this type of installation.

    Sorry for all my rambling but this is important stuff…. Good luck with your shower project!


  24. Avatar photo

    what about a niche the full length of a 5 foot shower. It is an exterior wall to a garage that is insulated. We are in Chicago which of course gets very cold in winter. Should we still stay away from a large horizontal niche on the wall to the garage or will it be ok using foam board and spray foam behind niche?

  25. Steves User Profile Image

    Hi Lorenzo,

    Thank you for your comment.

    I am not too concerned about cutting out 1 wall stud to accommodate your shower niche, as long as the appropriate structure was installed to reinforce the wall and support the niche.
    A single porcelain/ ceramic soap dish may not have been considered a significant breach in the original shower wall but a shower niche may be a different story. You would have to check with your local building authority about this.

    I would be more concerned with the use of Kerdi Board to replace the 5/8″ drywall of your shower wall. I have never seen any “fire rating” on any foam backer board. I would guess that using Kerdi Board in this situation compromises the firewall. In other words……when the people at UL gave you their opinion, they may have assumed that the tile substrate was fire rated drywall, not foam backer board.

    Unfortunately, I’m not really qualified to say what your HOA may do in this situation. I think it would be a good idea to get some kind of written assurance from your tiling contractor that your shower was rebuilt by qualified installers following the industry “best practices”. That may be your best evidence for your HOA in case they have any questions.

    I’m sorry that I couldn’t provide you with more reassurance.


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