When you build a shower you will eventually need to make some holes in it – it’s just part of the overall process. You’ll need to install frames or hinges for your shower doors, grab bars, shower curtain rods, a picture of your pet iguana – whatever. The problem is that now you have that completely waterproof shower you really don’t want to go poking holes into the waterproofing.

No matter which waterproofing method you’ve used any fastener penetrations will have to punch a hole into it. You want to make sure you install your screws properly in order to maintain the integrity of the waterproofing. You don’t want to ruin all your hard work because you need to drive a screw through it!

The first thing you need to do is mark the exact locations of your screw holes. Most things like grab bars come with little templates you can hold up and get exact placement. With shower door frames and stuff like that you can hold up the frame piece and mark the correct location.

Ideally you want to have the placement of things like grab bars in mind before you even put the substrate up on the wall. This way you can instal backing for them. A 2×6 between the studs in the right location eliminates the need to use wall anchors and gives you a solid framing piece to screw directly into. That isn’t always possible (things are added later, layouts change, etc.) but if you can do it you will save a lot of time.

Spade drill bit for tileOnce you have the location of the holes marked you need to take your drill and put a hole there – all the way through the substrate. I normally use the spade-shaped bits for most tile and stone. They look like the little arrow bits and are normally labeled for use with glass tile, they work with nearly any tile. Make sure you get the correct size for either your screw, if you have backing, or your anchor if you don’t. They look like this:

You want to drill slowly! If you attempt to drill too quickly you may burn up the bit and/or crack the tile. That sucks – just trust me on that one. It’s usually easier if you have a spray bottle with water and mist it down as you drill through the tile, it helps keep the bit cooled down.

Holes drilled for screws It’s also much easier to drill through grout lines if you can. That doesn’t always lay out correctly, but it helps tremendously if you’re able to do it.

For this particular post I’ll be using a small two foot grab bar installed on a shower wall. You can click on any of the horrible photos to see a full-size version.

Once you get the holes drilled through in the correct location get some 100% silicone and fill each hole all the way up to the surface. This particular grab bar has a total of six screws – three on each end.

penetrations filled with siliconeOnce the holes are filled with silicone push your wall anchors all the way in. Silicone will ooze out as you do this, it should – it means you have a full hole and there is enough silicone to seal whatever you place in there.

The little red things are the screw anchors I’m using. If you have solid backing behind your screw locations you can just skip this step – you know – since you aren’t using screw anchors.

If you do have backing and aren’t using anchors you need to ensure that you have screws long enough to penetrate through the tile, through the substrate and into the blocking you placed back there. 2″ or 2 1/2″ screws are normally what you want.Screw anchors placed in holes

When you have your holes filled with silicone, and your wall anchors in if you’re using them, go ahead and install your grab bar or whatever is causing you to drill holes into your brand new tile.

As you drive the screw in the silicone will seal the penetration. No matter which waterproofing method you’ve used, the hole will be sealed all the way from the surface of the tile to the area behind the tile substrate.



Waterproof grab bar installed

And there you have it. Completely waterproof fastener penetrations in your brand new tile. As long as you fill those holes with silicone you will never have problems with leaking or any other issues that commonly derive from poking a hole in your waterproof wall.

Besides, if you’re hanging a picture of your pet iguana in your shower you already have bigger problems to deal with…

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  • david

    I am using kerdi board in my shower. Since the Kerdi board has a soft foam core, I assume it is wise to install grab bar brackets directly into the studs before installing the Kerdi board for proper anchoring of the grab bars; or, even if the Kerdi board flexes to some degree, is it acceptable to tile over the Kerdi board, then mount grab bars after drilling through the tile ? My concern is the flexing of the walls at the grab bars because Kerdi board is “soft”. Is the latter type of installation acceptable, or will the tile eventually crack because of the repeated flexing of the wall due to the continual pressure on the grab bars ? If the former installation is better, what kind of grab bars can you recommend for mounting directly to the studs before installing the Kerdi board ?

    • Roger

      Hi David,

      The best thing to do is install a 2×6 between the studs where you want to install the grab bar, install the kerdi board and tile normally, then drill through the tile and kerdi board into the 2×6 to anchor your grab bar. Fill the drilled holes with silicone before inserting your screws.