The shower pan is the waterproof floor beneath the tile, and it is the most failure-prone part of any bathroom. A pan that leaks soaks the subfloor, rots framing, and stains the ceiling below, and the repair almost always costs more than the original installation. Building one from tile over a mortar bed produces a custom floor that fits any footprint, and a competent DIYer can finish the job in about eight hours of working time spread over three days, with materials running $400 to $1,000 for a typical alcove shower. Before committing to the build, understand that the waterproof membrane is the part protecting everything else: a torn shower pan membrane repair is the most common reason tile showers leak years after installation.
The steps below assume the pan goes over plywood subflooring. If you are building on a concrete slab, you will need a riser kit to raise the drain above the slab, and the liner work changes accordingly. This is an advanced project; even experienced remodelers describe the pan as one of the harder jobs in a bathroom.
Basics of Tiled Shower Pans
A shower pan, floor, or receptor is the sloped base that directs water to the drain. The classic mortar bed construction stacks three layers: a sloped dry-pack mortar base called the preslope, a waterproof liner, and a second mortar bed that carries the tile. The preslope guarantees the liner sits on a slope so water always runs toward the weepholes around the drain instead of pooling against the walls.
Mortar beds have been the standard for decades because they work. The materials are cheap, the geometry is forgiving, and a pan built this way can be re-tiled later without tearing out the floor. The trade-off is labor: mixing, packing, and curing add days to a project that a prefabricated pan finishes in an afternoon.
Pan Types Compared
| Pan type | Material cost | Skill level | Main trade-off |
|---|---|---|---|
| Mortar bed with liner | $400 to $1,000 | Advanced | Custom fit, repairable, slow |
| Prefabricated pan | $150 to $600 | Intermediate | Fast install, stock sizes only |
| Foam pan with coating | $200 to $700 | Intermediate | Lightweight, needs flat subfloor |
Prefabricated pans install quickly but lock you into stock sizes and a factory slope. Mortar beds take longer and demand more skill, yet they adapt to any drain location and any footprint, and a damaged section can be repaired rather than replaced. Whatever the pan type, the liner and its seams carry the waterproofing load, and damaged shower pan membrane repair starts with finding the tear before water finds the framing.
How the Layers Work Together
Each layer has one job. The preslope moves water toward the drain, the liner blocks it from reaching the subfloor, and the top mortar bed protects the liner from traffic and tile work. The liner laps up the walls 6 to 8 inches and over the curb, with inside corners folded and patched so the membrane stays continuous at every change of plane.
Why the Preslope Matters
Without a preslope, water sits under the top bed against the liner, and standing water eventually finds a pinhole. The preslope pitches 1/4 inch per foot toward the drain, enough to keep the liner dry between showers.
Planning and Materials
Measure the shower footprint and confirm the drain location before buying anything. The floor must slope a minimum of 1/4 inch per foot from the farthest wall to the drain, and a drain that cannot be moved forces the slope to work around it. Sketch the layout, mark the wall studs, and order everything at once so the job does not stall mid-build.
Material List
- Dry-pack mortar mix made from sand mix and Portland cement
- PVC or CPE shower liner membrane
- Liner sealant and prefabricated corner patches
- Clamping drain with weepholes
- Cement backer board and waterproofing membrane for the walls
- Thin-set mortar, tile, and grout
Order the liner and drain as a matched set. Liners and clamping drains are sized to each other, and mismatched parts are the most common reason a pan fails during the first fill test. Most suppliers sell the two together, and the few dollars saved by mixing brands is not worth a redo.
Tools You Will Need
A trowel, a level, a straightedge for screeding the slope, a utility knife for liner cuts, and a rubber mallet for seating tile. A margin trowel and a wood float speed the mud work. First-time installers should watch a complete walkthrough before cutting anything, such as the tile shower installation video series from Fine Homebuilding, which covers the pan from preslope to finished tile.
Step-by-Step Shower Pan Construction
The work splits into three sessions so each mortar layer cures before the next begins. Work in the order below and do not skip ahead, because each layer hides the defects of the one underneath.
- Build the preslope. Pack dry-pack mortar from the drain to the walls at 1/4 inch per foot, screeding against guides marked on the studs, and cure overnight.
- Install the liner. Cut the membrane to cover the floor and lap 6 to 8 inches up the walls. Fold the inside corners, patch them with membrane, and seal every seam with liner sealant.
- Set the drain. The clamping ring traps the liner against the drain body, and the weepholes must stay open so water from the top bed can escape.
- Build the curb. Stack treated lumber or pack mortar into a curb form, wrap the top and sides with liner, and staple the liner above the finished curb height. The curb is the foundation of the shower entrance, and a durable shower pan threshold depends on a solid core before any tile goes on.
- Pour the top mortar bed. Pack mortar over the liner at the same slope, feather it at the drain, and cure before tiling.
- Waterproof the walls and curb with sheet or liquid membrane, then set tile with thin-set, grout, and sealant.
The Preslope Is Not Optional
Skipping the preslope is the most common shortcut, and it is the one that fails first. Without it, water pools beneath the top bed, the liner stays wet, and the pan develops a musty smell within a year. The extra half day of work costs almost nothing in materials.
Sealing the Drain Connection
The drain is the only penetration through the liner, which makes it the most likely leak point. The liner must be clamped watertight between the drain body and the clamping ring, and the weepholes must stay clear of mortar so water collected on top of the liner can drain out. Check the clamp pressure twice before pouring the top bed, because the drain is impossible to reach after the mud sets.
Waterproofing the Curb and Corners
Corners and the curb concentrate stress: the liner folds at every inside corner, and the curb takes standing water, foot traffic, and the constant spray from shower doors. Each transition needs its own waterproofing detail, and skipping any one of them opens a path for water.
Corner Patches
Liner folds leave gaps at inside corners. Prefabricated corner patches, or hand-cut squares of membrane sealed with liner sealant, close the gaps. Do not force the liner flat at corners; folds that are cut and patched seal better than folds that are stretched thin.
Seal the liner to the drain flange with a bead of sealant as well. Two layers of protection at the highest-risk point cost pennies and save a full tear-out later.
Curb Height and Slope
Most building codes require the curb to sit at least 2 inches above the finished drain height, and the top surface must slope back toward the shower. A level curb holds water on its top, which wicks through grout and into the wall over time. The doorway side of the curb follows the same rules: shower pan threshold design and installation needs a waterproof core, a sloped cap, and sealed transitions at the jambs.
When to Hire a Professional
Experienced tile setters build mortar pans quickly because they have done hundreds. A first-time DIYer should weigh the material bill against the cost of a mistake: a leaking pan discovered after the bathroom is finished means tearing out tile, bed, and liner and starting over.
Signs the Job Is Beyond DIY
A pan that must sit over a slab without a riser, a drain that needs relocating in concrete, or an out-of-level floor all push the job toward a professional. Unusual shower footprints multiply the liner-folding work at every corner. The curb and threshold are a reliable difficulty gauge: leakproof curb installation requires folded liner, dam corners, and a sloped cap, and anyone uncomfortable with those details will struggle with the rest of the pan.
What a Pro Costs
Professional tile showers typically run $1,500 to $4,500 in labor for a standard alcove, with the pan representing a third or more of the total. Compare that with a DIY material bill of $400 to $1,000 and the savings are real, but they evaporate if the first attempt leaks. Budget for the drain assembly and the liner as the two items where cheaper parts cost more later.
The mortar bed pan rewards careful work: each layer depends on the one below it, and the order cannot be rushed. Build the preslope, seal the liner, protect it with the top bed, and waterproof the transitions, and the floor will outlast the fixtures around it. Homeowners who want reliable waterproofing without the mud work can switch to grout-free engineered stone shower panels, a solid-surface alternative that skips mortar and tile entirely while delivering the same leak protection.