When weep holes in the shower drain become blocked or clogged, a disaster may be in the making. Weep holes provide a valuable service in draining away underfloor moisture that has seeped through grouting and corners. If water penetrates through the tile grout and joints, the weep holes help it to find its way into the drainage system. If the weep holes are blocked, the water builds up and is forced into the walls and flooring in a two-story home, you may have damage to the first-floor ceiling.
At the bottom of the pan there are three weep holes in the metal drain. These can be accidentally plugged up during installation, or caused by a build up of lime. Here you'll learn first how to unblock lime scale (Method 1) and how remake the shower base if the problem is being caused by other materials (Method 2).
Method 1 - Remove Build-up
You may be lucky enough to have a simple lime build-up block. Find the weep holes by unscrewing the plug hole/top part of the drain hole. Look inside and you will see small holes around the outside of the main pipe. Stick a piece of thin wire through the holes if you see a white, crusty build-up. If your weep holes are subject to blocking with lime scale, they will have to be cleaned regularly to avoid water building up and damaging the floor.
Method 2 - Remake Shower Base
If the weep holes have been blocked by mortar or tile grout, you will have to pull up the entire shower base and remake it.
Step 1 - Remove the Shower Base
Pull up the tiles and shower base, exposing the sub floor. Remake the shower base, remembering to properly install the new shower base over a pre-sloped floor.
Step 2 - Cement the Floor
Install the new floor mortar while keeping the weep holes open with crushed tile or small pebbles. If you are putting in a tar pan, make sure you place a large nail in each weep hole to avoid the holes being blocked with tar. The nails should still be in the holes after the hot mopper leaves. Wiggle the nails as you remove them so the the holes remain fully open.
Step 3 - Widen the Weep Holes
Before you lay the mortar bed, enlarge the holes with a drill. Take a drill with a 0.25-inch mortar bit. Hold it sideways as close to the tar pan as possible and aim for the tiny existing weep holes in the drain. Throw the bit away after enlarging the holes. Be careful with this step as it is easy to damage the drain pipe.
Step 4 - Tile the Floor
Stack a good amount of gravel or crushed tile around the weep holes. Cut out a donut hole of brown paper to cover the gravel to protect the gravel from tile grout. When installing your shower base, make sure to pile pebble-sized gravel around the drain to keep the weep holes open while cementing