There are two types of water drainage called weep holes. There are weep holes in the shower drain in the floor beneath the tile, and there are (should be!) weep holes at the bottom of the tile installation on shower walls above a tub or acrylic shower base. They both do the same thing (allow water behind the tile to drain), needed for different installations. I will address both here.
Weep holes in shower drains beneath shower floor tile
In a traditional shower floor (with a pre-slope, rubber liner, top slope then tile) weep holes are required in the shower drain. The top mud deck, or top slope (the deck mud onto which the tile is installed) will remain saturated with water (if the shower is used regularly). This is called a water-in, water-out system. Water will get behind your wall tile, and beneath your floor tile. When properly constructed your shower has the waterproof liner installed over a pre-slope, then deck mud is installed over that with tile bonded directly to it. The water that gets behind your tile will run down your waterproofing and into the floor liner. That water will soak into the deck mud on the top slope. This is normal! With every use, the water will flush through, with new water getting behind your tile and forcing the old water down, eventually into the drain. This is water-in, water-out. When unused, gravity will draw that water down toward the drain. Since this layer is below your tile, so below the top opening of your drain, that water needs a way to enter the drain. That is the purpose of weep holes in your shower drain. Regardless of your brand of clamping drain, the weep holes will be integrated into the upper flange. A clamping drain is called that because the rubber liner…wait for it… is clamped between the upper and lower flange, creating the seal. Tile product manufacturers aren’t known for their originality.🤷♂️ This image shows the hole in the liner, centered over the lower flange (place silicone beneath the liner to help seal it). The upper flange is the black ring sitting next to it. The keyhole-shaped holes are placed over the bolts, twisted to lock in place, and tightened down to clamp the liner between the two flanges and seal it. If you look at that ring the four little channels along the edge that run inward toward the four holes are your weep holes. The water runs through those channels and down into the weep holes into the drain.
Since I’m just a tile guy I”m not usually up on all the new technological crap that has nothing to do with tile, like online video or the ‘SlapChop’. I’ve decided that since I spend most of my days in other people’s showers that I should get out more and learn something else.
So naturally, since I own kitchen knives and don’t need a SlapChop, I decided to make a video about a tile subject. So here is my first video, sans sound because in audio I sound like a drunk leprechaun, for my readers. Umm – that’s you.
And since I actually have a day job and bills to pay all you get is a time-lapse photography of the creation of a mud deck for a tiled shower floor. But I’m gonna call it a tile video ’cause Google loves that shit.
Once you have your entire perimeter done you simply need to pack deck mud into the rest of the base from the perimeter to the drain. Once again – beat the hell out of it. Seriously, pack it in there really well. The more dense your floor is the better. You need to ensure that the line of the floor is straight from the wall to the drain all the way around without any major humps or dips. It takes time and patience – use both. This step is critical since this is the substrate your tile will be installed upon.
Well, you’ve made it to the final step. If you have arrived at this portion of the instructions without first reading the rest, start with How to Create a Shower Floor. Go ahead, I’ll be right here when you get back. I’ll just sit back and drink this beer Pepsi while I wait.
Okay, now that we’ve ensured that your shower liner is indeed waterproof and won’t leak into your dining room and carve the Grand Canyon into your basement we’re ready for the final portion. The top mud bed is the surface onto which your shower floor tile is actually installed.
What we will now be doing is fabricating your top mud bed directly over the top of your waterproof liner. The top bed will be 1 1/4″ to 1 1/2″ thick – consistent throughout from the drain to the wall. Since you have a pre-slope beneath your liner (umm, you DO have a pre-slope beneath your liner, right?) you already have the correct slope for drainage. By making a consistent mudbed for your top slope it will follow the slope for the same amount. Know what I mean?
Well now we’re ready to waterproof your curb. If you have reached this post before reading the previous two, start with How to build a shower floor from the beginning. Now that you’re ready to get the curb cut and waterproofed lets get it done.
And yes, I know my pictures suck – I’m a tile guy for cryin’ out loud, not a professional photographer. Until you try to balance a liner, a razor knife, a margin trowel, and a camera while trying to take a photo don’t give me any crap about it. Oh, and you can click on any of the images for a full-size version – partake in the full glory of how much my photography sucks.
We need to start by finding the inside lower corner of your shower pan and making certain that the liner is pressed firmly against it. Then follow it up the corner of the curb and wall to the top inside corner of your curb. This is the spot at which you will start the cut in your liner.
Now that you have your curb built and your pre-slope done (if you haven’t done this yet check out How to create a shower floor, Part 1) you are ready to install your waterproof liner.
Purchasing a waterproof liner
When you order or buy your liner you need to get one large enough for your shower. The liner you get has to be at least one additional foot larger than each of your measurements. For instance, if your shower floor is three feet by five feet your liner needs to be four feet by six feet. This allows enough to run the liner up the wall behind your backerboard six inches each way. You also want to purchase two “outside” corners for your curb. These are pre-formed corner pieces to waterproof the ends of your curb after you cut the liner.
I usually order mine two feet larger in each direction. Six inches is the minimum. Specifications state that your liner must run up the wall at least three inches above your curb. So if your curb is three inches high your liner needs to run at least six inches up each wall. I usually go a foot above the curb – overbuilding your shower is rarely a bad thing.
This series covers building a traditionally waterproofed shower floor using a clamping drain and rubber liner. Each step builds on the previous one — skipping steps is how shower floors fail.
Building the curb and installing the pre-slope<-You are here Creating the foundation that ensures water moves toward the drain — not into your framing.
Positioning and installing the shower liner Correct placement of the liner over the pre-slope and into the drain assembly.
Forming the liner around the curb and flood testing Properly wrapping the curb and verifying the liner is watertight before moving forward.
Finishing the drain and forming the level perimeter Setting drain height and creating a consistent, level perimeter for the final mud bed.
Tying in wall waterproofing and finishing the mud bed Integrating the walls with the floor and completing the final sloped surface.
Curb and Pre-slope
Properly built shower
There are a couple of options to create a shower floor for tile using deck mud. The first is a single-layer shower floor which can then be coated with RedGard or a similar product or covered with kerdi to waterproof it. The other is a normal shower floor with a liner which will have two layers – a preslope, the liner, then the top slope which is then tiled. This series of posts will describe the latter.
Before we start I should note that unless you are using the kerdi waterproofing method or utilizing a liquid membrane as your floor liner you should not have the backerboard installed in the bottom part of the shower. Your waterproof membrane for a shower floor will be installed behind your backerboard. The curb and pre-slope need to be completed before installing the lower wall substrate.
Creating the curb for a wooden floor
The first thing you must do is create the outside curb of your shower. You need to create the “box” which will become the inside of your shower floor. Depending upon whether your shower will be created on a wood or concrete floor will dictate what material you use for your curb.
If you have a wooden floor you want to use regular dimensional lumber. The 2 x 4’s they carry at Home Depot – those. That is the easiest and most readily available material. Ideally you want to use kiln-dried lumber. That is lumber that is, well, dried in a kiln. By removing moisture in this manner the moisture content of KD lumber is normally between six and eight percent compared to regular dimensional lumber at close to 15%. Why does that matter? Well moisture and wood don’t mix. As it dries wood has a tendency to warp and twist. The less moisture initially in the wood the better. KD lumber is best and regular air-dried dimensional lumber is also acceptable. NEVER use pressure treated lumber – ever.
