Bathtub Pan Liners: Necessary Or Not?

A shower pan liner is a waterproofing membrane that looks like a thick plastic sheet. It is installed under the tile or acrylic shower pan and beneath any grout or mortar used to fix the shower enclosure in place. It is a completely watertight base that prevents water damage to the floorboards underneath the shower.

A bathtub liner, on the other hand, is a solid insert that is placed inside your existing tub to give it a new look without the hassle of installing a new one. It is moulded out of PVC or acrylic and fits over the current tub, reducing its size slightly.

So, while a shower pan liner is necessary to prevent water damage, the need for a bathtub liner depends on the condition of your current tub. If your bathtub is worn out, chipped, or rusted, you may want to consider either installing a new one or giving it a facelift with a liner or refinishing.

What is a shower pan liner?

A shower pan liner is a waterproofing membrane that looks like a thick plastic sheet. It is installed under the tile or acrylic shower pan and beneath any grout or mortar used to fix the shower enclosure in place. It is made out of a single sheet of polyvinyl chloride or PVC and is installed under everything else used to build your shower.

The shower pan liner serves as a final layer of protection for your home against any water that might escape from a damaged shower floor or pan. It is designed to capture any droplets and stop water from damaging wood studs, the subfloor, or the structure of the home. It is a completely watertight base for your shower enclosure.

The installation of a shower pan liner is not an easy task and is quite difficult for beginner DIY enthusiasts. However, more advanced DIYers with construction and plumbing knowledge will find it an enjoyable project. The process is quite involved and requires specific materials, such as a Portland Sand/cement mixture, and careful adherence to the installation steps.

The shower pan liner is an important component of a shower as it provides a durable and effective defence against water damage, which can be costly to repair.

Pros and cons of a shower pan liner

A shower pan liner is a waterproofing membrane that acts as the final layer of protection for your home against any water that might escape from a damaged shower floor or pan. It is made out of a single sheet of polyvinyl chloride or PVC and installed under everything else used to build your shower.

Pros:

• It provides a completely watertight base for your shower enclosure, preventing water damage to the floorboards and the structure of your home.
• It is durable and long-lasting, with an expected lifespan of up to 50 years.
• It is hidden and does not affect the aesthetics of your shower.
• It is cost-effective, with pre-measured kits available for around £50-£100.

Cons:

• Installation can be difficult and time-consuming, especially for beginners. It requires advanced knowledge of construction and plumbing.
• It may not be necessary in all showers, depending on the design and materials used.
• It adds an extra step and cost to your shower installation process.

Installation of a shower pan liner

Installing a shower pan liner is a complex task that requires advanced knowledge of construction and plumbing. It is not recommended for beginner DIYers. Here is a step-by-step guide on how to install a shower pan liner:

Step 1: Cut a Hole in the Shower Floor

Cut a 4.5-inch diameter hole in the centre of the shower floor where the tile shower drain would typically be located.

Step 2: Prepare the Tile Shower Drain

Disassemble the tile shower drain and lay the drain base in the opening. Ensure that the flange of the drain base rests on the subfloor.

Step 3: Solvent-Weld the Drain Base

Use the appropriate solvent cement to solvent-weld the drain base to the drainpipe.

Step 4: Cover the Drain Base

Cover the drain base opening with duct tape to prevent debris from entering the drain.

Step 5: Apply the Mortar Bed

Apply a Portland Sand/Cement mixture mortar bed over the subfloor. Ensure a slope of 1/4 inch per foot from the wall framing to the top of the drain base without covering it. The sloped mortar bed should be flush with the top surface of the drain base.

Step 6: Measure and Cut the Pan Liner

After the mortar bed has cured, measure the pan liner dimensions. It should cover the floor, turn up all sidewalls at least 2 inches above the finished curb height, and adequately cover the curb. Lay the pan liner on a clean floor, measure, and cut to size. Seaming may be required for larger showers; follow the instructions on the bonding adhesive.

Step 7: Prepare the Drain Base and Pan Liner

Remove the tape from the drain base and apply a 1/4-3/8 inch bead of 100% silicone caulk around the upper surface, 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. Lay the pre-measured pan liner over the drain body, cutting an "X" at the top of each bolt to slide the liner over the bolts and onto the drain base. Press the pan liner firmly to ensure a seal.

Step 8: Work the Pan Liner into Place

Work the pan liner material from the drain body to the sidewall framing and curb threshold, ensuring it lays flat on the floor surface. If desired, use an adhesive compatible with the pan liner to bond it to the floor and curb.

Step 9: Secure the Pan Liner

For outside corners or curbs, cut the pan liner as needed and use a dam corner to cover the cut area. Use the appropriate adhesive for PVC or CPE liner installations.

Step 10: Cut Out the Drain Hole

Locate the drain hole on the drain base and cut out the corresponding area in the pan liner. Place the clamping ring over the bolts and slide it counterclockwise to lock it in place. Tighten the bolts, ensuring the weep holes are clear of any residual liner material or silicone.

Step 11: Water Test the Installation

Close off the drainpipe opening and fill the shower floor with water just below the top of the curb. Let it sit for four hours and observe for leaks. Repair any leaks found and retest until the installation is leak-free.

Step 12: Apply a Reinforcement Bed of Mortar

Before applying the final mortar bed, nail water-impervious drywall to the wall studs, approximately 1 inch above the pan liner surface. Then, place pea gravel over the weep holes to prevent them from being completely covered by mortar. Apply a minimum 1-1/2 inch reinforcement mortar bed of concrete over the pan liner, leaving space for the final thin-set and tile application.

For further information, there are several YouTube videos available that demonstrate the installation of a shower pan liner.

Cost of a shower pan liner

A shower pan liner is a waterproof mat that you install under shower tiles to prevent water from seeping through to the floorboards. Installation is not a simple task and is not recommended for beginner DIYers.

The cost of a shower pan liner varies depending on the size of the shower, the type of liner, and whether you hire a professional or do it yourself.

Cost of Materials

Basic prefabricated shower pan models, such as those made of fiberglass or acrylic, are the most affordable option, starting at around $150. More durable options include PVC and stone resin, while natural stone, cast iron, or tile are premium options that will cost more.

Cost of Professional Installation

Labor costs for a professional shower pan installation typically start between $350 and $570 for a simple replacement. The overall cost will depend on the size and type of shower pan, as well as the complexity of the installation. For example, a custom shower pan will cost more for both materials and installation.

Additional work, such as tiling over a basic shower pan liner or installing a new drain line, will also increase the total cost.

DIY Installation

If you have the necessary tools and skills, you can opt for a DIY installation to save on labor costs. A DIY shower pan installation can cost as little as $220-$520 for a fiberglass shower pan, including the cost of the pan, shower drain assembly, plumber's putty or silicone caulk, and mortar.

However, it's important to consider the heavy labor that may be required for a DIY installation, especially if you're working with heavier materials like cast iron or stone.

Other Factors Affecting Cost

Several other factors can influence the overall cost of your shower pan installation:

• Accessibility modifications: Low-threshold shower pans and other accessibility features for walk-in showers can increase the cost by $700-$1,000.
• Pairing with other projects: Combining your shower pan installation with other projects, such as replacing your shower door or installing tile shower walls, will add to the overall cost.
• Plumbing alterations: If you're moving your shower to a different location, you may need to move the drain and cut a new drain hole, which will require plumbing services.
• Shower base replacement: In some cases, you may also need to replace the shower base or subfloor, which can cost an additional $225-$650.
• Permits: Certain projects, especially those involving structural changes or plumbing alterations, may require permits, which can cost anywhere from $30 to $500.

Example Quotes

To provide a frame of reference, here are some example quotes for shower pan liner installations:

• An $800 quote for a mud pan installation, including labor and materials, for a 3'x4' shower.
• A charge of $30 per foot, including materials, exclusively for the shower pan installation, with tile installation as a separate cost.
• A basic shower liner installation, including labor and materials, starting at $1,468-$1,801 per shower.

Comparison to other options

There are three main options to consider when dealing with a worn-out bathtub: replacing the bathtub, refinishing the bathtub, or installing a bathtub liner.

Installing a new bathtub is a good option if you are remodelling your bathroom and replacing the tiles or tub surrounds. However, if you are not planning other changes, installing a new bathtub may involve more construction than desired. Replacing a whole bathtub can cost thousands of dollars and may involve fixing the floor, walls, and plumbing.

Refinishing or reglazing the bathtub is a cheaper and faster alternative to installing a new bathtub or a bathtub liner. It involves removing the outer surface of the bathtub, sanding it down, and then resurfacing it with a special paint designed for bathtubs. Refinishing can be done yourself or by a professional and usually takes about five hours, with an additional one to twelve hours of drying time. A restored bathtub can last another ten to fifteen years, which is similar to the life expectancy of a new tub.

Compared to refinishing, installing a bathtub liner requires less construction in your house as most of the work is done in a shop. However, bathtub liners are more expensive, with prices starting at around $850, and they can be prone to mould and odour issues due to water becoming trapped between the liner and the bathtub. Liners also reduce the size of the bathtub basin and may feel weak or spongy underfoot. Additionally, the acrylic finish of bathtub liners is noticeably different from the glossy finish of porcelain tubs.

Frequently asked questions