The Ultimate Guide: Installing Pan Liners Easily

Installing a shower pan liner is a complex process that requires advanced knowledge of construction and plumbing. It is a crucial step in shower installation, as it ensures waterproofing and protects the subfloor from water damage. The shower pan liner is a waterproof mat installed under shower tiles, preventing water from seeping through to the floorboards. The process involves multiple steps, including preparing the slope, measuring and cutting the pan liner, installing the drain base, and securing the pan liner. The type of liner used, such as PVC or CPE, and the specific installation method may vary depending on the shower design and subfloor material.

How to Install a Pan Liner

Prepare the subfloor

The subfloor is the bottom-most layer of your shower floor. Before installing a pan liner, you must ensure that your subfloor is clean, dry, and free of debris. It is also important to check that your subfloor is level and structurally sound. If there are any uneven areas or damage, you will need to repair them to create a smooth and sturdy surface for your pan liner installation.

Once the subfloor is prepared, you can begin creating a slope. This is typically done using a mortar bed, which should be applied at a slope of 1/4" per foot, sloping inward from the wall framing towards the top of the drain base. Make sure to follow the manufacturer's instructions for the recommended slope and curing time. After the mortar bed has cured, you can determine the dimensions and placement of your pan liner.

It is crucial to ensure that your subfloor is properly prepared and level to create a solid foundation for your shower pan liner installation. Any imperfections or unevenness in the subfloor can affect the final outcome and the overall performance of your shower. Take your time during this step to ensure a successful installation.

Another critical aspect of preparing the subfloor is ensuring proper waterproofing. This is essential to prevent water damage and the growth of mould or mildew. After the mortar bed has cured, apply a layer of waterproofing material, such as a shower pan liner kit or a liquid membrane. Follow the manufacturer's instructions for proper application and curing time.

After the waterproofing layer has cured, you can proceed with the next steps of the installation, including measuring and cutting the pan liner to fit your specific shower dimensions. Remember to refer to the manufacturer's instructions or seek guidance from a professional if you are unsure about any aspect of the installation process.

Cut a hole for the drain

To cut a hole for the drain, you will need to follow these steps:

First, ensure that your pre-sloped mortar bed is completely dry and free of debris. Make a five-inch mark up from the curb onto the wall framing. Take measurements from that mark down to the mortar bed to determine the application height.

Next, lay the shower pan liner on a clean, flat surface. Measure and mark the total length and width of the mortar bed according to the diagram provided. Finally, cut the pan liner according to your markings. The total mortar bed length should be twice the application height, plus the mortar bed length. The total mortar bed width should be the total curb width, plus the mortar bed width, plus the application height.

Now, remove the test plug from the drain and drape the pan liner over both the mortar bed and the drain base, ensuring that the wall-facing edges are folded according to the length of the application height. Make sure the pan liner is centred before you locate the drain plug. Cut X shapes over the four bolts that the clamping ring screws into. Also, cut out a hole over the drain hole.

Fold the pan liner halfway over to expose the drain base and apply silicone caulk around the surface of the inner flange. Fold the liner back over, push the bolts through the X shapes in the liner, and screw the clamping ring down over the four bolts. Finally, tighten the bolts until the ring has a snug fit against the liner. Put the test plug back into place.

Now, work the pan material from the drain body to the sidewall framing and curb threshold so that it lays flat on the floor surface. If desired, an adhesive can be used to bond the pan liner to the floor and curb. Prior to the use of adhesive, make sure the adhesive is compatible with the pan liner.

Finally, locate where the drain hole is on the drain base and cut out the pan liner material to the dimension of the drain hole on the drain base. Place the clamping ring over the bolts and slide the ring counterclockwise so that it's locked in place. Tighten the bolts so that they are snug. Make sure the weep holes are clear of any residual pan liner material or silicone.

Install the drain base

To install the drain base, start by cutting a 4-1/2-inch diameter hole in the centre of the shower floor for the drain assembly. You can start with a smaller hole and cut away more material with a utility knife if needed. Place the drain base in the hole and ensure that the liner doesn't block the drain's weep holes. You may need to route a channel to ensure the top of the drain flange is flush with the subfloor.

Once you have a good fit, use adhesive silicone caulk on both sides of the liner where it contacts the drain. Then, solvent-weld the drain base to the drain pipe using the appropriate solvent cement. Cover the drain base opening with duct tape to keep debris from entering the drain.

Now, lay the liner over the subfloor and cut a hole for the drain. To prevent the small weep holes in the drain from getting clogged with cement or debris, place washed pea gravel over the holes. Cover the drain base opening with duct tape to keep out debris until you’re ready to add the finished drain.

Measure and cut the pan liner

Before you measure and cut the pan liner, you must install a sloped mortar bed. This is an essential step in the installation process, as it ensures that any water that gets through the tile and grout is channelled into the weep holes in the drain assembly.

Once the sloped mortar bed has cured, you can determine the pan liner dimensions. The pan liner should be large enough to completely cover the floor, turn up all sidewalls at least 2" above the finished curb height, and adequately cover the curb.

Now you can measure and cut the pan liner. Lay the liner on a clean, flat surface. Measure and mark the total length and width of the mortar bed. Finally, cut the pan liner according to your markings.

Total mortar bed length: 2 x application height + mortar bed length

Total mortar bed width: total curb width + mortar bed width + application height

Attach the pan liner to the drain

Attaching the pan liner to the drain is a crucial step in the installation process. Here is a detailed, step-by-step guide on how to attach the pan liner to the drain:

Prepare the Drain Base:

Start by placing the drain base into a pre-cut hole. The recommended size is a 4-4.5 inch hole for a tile shower drain. Screw the flange of the drain base securely onto the subfloor. If your drain is pre-assembled, loosen the bolts connecting the clamping ring to the flange and remove the ring, keeping the drain plug in the middle. Cover the drain hole with duct tape to prevent debris from entering.

Create the Slope:

You have two options for creating the slope: using mortar or a pre-made product like Oatey's Perfect Slope. For the mortar option, pour mortar onto the subfloor at a slope of 1/4 inch per foot, sloping inward from the wall framing towards the top of the drain base but not over it. Allow the mortar bed to cure according to instructions. If using a pre-made product, follow the manufacturer's instructions for installation, ensuring it fits flush with the drain.

Apply Adhesive to Drain Base:

Before installing the pan liner, remove the duct tape from the drain base. Apply a bead of 100% silicone caulk around the upper surface of the drain base, approximately 1 inch from the outside edge. This creates a seal between the pan liner and the drain base. Screw the clamping ring bolts into the drain base, leaving 2-3 thread depths exposed.

Position the Pan Liner:

Lay the pre-measured pan liner over the drain body and the mortar bed or pre-made slope, ensuring it is centred. Cut X shapes over the bolts of the clamping ring and a hole over the drain hole. Ensure the liner doesn't interfere with the drain's weep holes.

Secure the Pan Liner to the Drain:

Fold the pan liner in half to expose the drain base. Apply silicone caulk around the inner flange. Fold the liner back and push the bolts through the X shapes. Screw the clamping ring down over the bolts and tighten until snug. Put the test plug back into the drain.

Test the Installation:

After allowing adhesives to cure, perform a flood test. Securely plug the drain pipe and fill the shower bed with water up to the curb height. Let it sit for at least 2 hours (or 4 hours, according to some sources) to check for leaks. If the water level hasn't dropped and the surrounding area is dry, your installation is watertight.

Frequently asked questions