Installing a tub with a built-in shower is a practical solution for bathrooms where floor space is at a premium. Modern designs combine a deep soaking tub with an integrated showerhead, allowing you to bathe children, rinse off after a workout, or enjoy a quick shower without the need for a separate shower stall. When installed correctly, this setup adds functionality and value to your home. This guide walks through every stage of the process—from planning and material selection to final waterproofing and maintenance—so you can achieve a professional result.

Planning Your Installation

Successful installation begins with accurate measurement and thoughtful layout. Start by measuring the available alcove or corner space, noting the rough opening width, depth, and height. Standard tub-and-shower combos range from 48 to 60 inches long and 30 to 36 inches wide, but compact models as short as 40 inches exist for tight spaces. Confirm that the doorway and any interior corners will allow the tub to be maneuvered into the room.

Check the location of supply and drain lines. If you are replacing an existing tub, the new tub's drain and overflow must align with the existing waste line, or you will need to relocate the plumbing. For new construction, position the drain within 6 inches of the tub's drain outlet to avoid excessive pipe work. Also verify that the floor is level and strong enough to support the filled tub (a standard 60-inch tub holds 40 gallons, adding over 330 pounds of water weight). If the subfloor is compromised, reinforce it with plywood or sister joists.

Consider clearance for doors and windows. A shower curtain or glass door needs enough swing space. If you plan to add a hinged door, check that the door will not hit a toilet or vanity. Lastly, check local building codes—most areas require a licensed plumber for drain lines and may require a vapor barrier behind cement board for wet areas.

Choosing the Right Tub-and-Shower Combination

Types of Tub Units

Alcove tubs are the most common choice for built-in showers. They fit between three walls and often come with an integral tile flange. Corner tubs fit into a 90-degree corner and can free up wall space. Drop-in tubs require a deck to be built around them, which adds cost but allows custom styling. Some freestanding clawfoot tubs now include a telephone-style shower attachment; while they save physical space, they usually lack the containment of a traditional enclosed shower.

Materials

Acrylic and fiberglass-reinforced plastic (FRP) dominate the residential market due to their light weight, ease of installation, and low maintenance. Acrylic is more durable and resists scratches and fading better than gel-coated fiberglass. Enameled steel tubs are heavier and more chip-resistant but can be cold to the touch. For the shower enclosure, consider solid-surface or tile for a premium look, but be prepared for added weight and waterproofing complexity.

Features to Look For

Look for a tub with a pre-leveled base and an integral tile flange to simplify waterproofing. Slip-resistant floor texture is important for safety. Some tubs include molded storage ledges or grab bars. Choose a shower trim kit with a hand-held sprayer for versatility. Ensure the tub's depth allows comfortable bathing: 14-inch depth is standard, while 18–20 inches offers a deeper soak.

Essential Tools and Materials

  • Tub-and-shower unit (with flange, drain, and overflow pre-attached if possible)
  • Plumbing supplies: copper or PEX pipes, brass fittings, Teflon tape, pipe cutter, crimp rings (PEX), and solder/flux (copper)
  • Drain and overflow kit (if not included with tub)
  • Cement board or foam backer board (1/2-inch thickness for walls)
  • Waterproofing membrane (liquid-applied or sheet membrane like Kerdi or RedGard)
  • Cement board screws (alkali-resistant, 1-1/4 inch for cement board to studs)
  • Thin-set mortar (modified for tile and waterproofing membrane)
  • Tile and grout (choose porcelain or ceramic rated for wet areas)
  • Caulk (100% silicone for corners and joints; avoid acrylic caulk in wet areas)
  • Shower valve, trim kit, and showerhead/arm (verify flow rate and handle style)
  • Level (4-foot and torpedo), measuring tape, carpenter's square
  • Drill with screw bits and mixing paddle, diamond blade or tile cutter
  • Rubber mallet, shims, utility knife
  • Protective gear: gloves, safety glasses, knee pads

Preparing the Bathroom

Before the new unit arrives, empty the room. Remove the old tub, toilet, vanity, and any wall surface material down to the studs within the shower area. Inspect the subfloor and wall studs for water damage, rot, or mold. Replace any compromised wood and treat the area with a borate-based preservative if moisture issues were present.

Install an exhaust fan if one is not already present; it should be rated for the bathroom's volume and vented to the exterior. Fan placement near the shower outlet is ideal. Consider adding a vent pipe for the tub drain if the existing waste stack is too far away. All venting should comply with local codes—typically a 1.5-inch or 2-inch dry vent running to the main stack.

Level the floor in both directions. If the floor slopes more than 1/8 inch per foot, use a self-leveling compound. A level base prevents water from pooling inside the tub and keeps the tile flange aligned correctly with the backer board.

Installing the Tub

Positioning and Leveling

Set the tub in place temporarily to test fit. Check that the drain outlet aligns with the stub-out in the floor. Mark the stud locations for the flange and shimming. Remove the tub, then apply a thin layer of mortar (or a bed of sand) on the floor where the tub base will sit—this supports the bottom and prevents flexing. For acrylic tubs, some manufacturers recommend a polyurethane foam bedding kit instead of mortar.

Set the tub back in place and press it into the mortar. Use a 4-foot level to check both lengthwise and widthwise. Shim behind the flange at each stud to plumb the tub vertically, using plastic shims. Over-shimming can crack the flange; drive the shim gently until the level reads true. Secure the flange to the studs using tub screws or roofing nails with neoprene washers. Do not overtighten—cock the fastener so the flange lies flat.

Connecting the Drain and Overflow

Attach the drain shoe and overflow pipe per the manufacturer's instructions. Most modern kits use a compression gasket on the overflow hole and a threaded drain tailpiece. Apply plumber's putty under the drain flange and tighten the strainer into the shoe from above. Connect the waste line to the trap (typically a 1.5-inch PVC or ABS trap). Run the trap to the building drain using a 90-degree sweep elbow. Test for leaks by pouring a few gallons of water into the tub and checking under the floor.

Installing the Shower System

Install the shower valve body before the walls are closed. Mount the valve at a standard height of 38–42 inches from the floor, or adjust based on the homeowner's needs. Use drop-ear elbows or a valve box to secure the valve to a stud. Solder or crimp the connections, then apply water pressure to test for leaks before installing the backer board. Cap the valve openings temporarily to keep out debris.

After tiling, install the shower arm (typically 5–6 inches from the valve center to the showerhead height of 72–78 inches). Use Teflon tape on threaded joints. Attach the showerhead and handle trim, applying a thin bead of silicone behind the escutcheons to prevent moisture behind the trim.

Waterproofing and Backer Board Installation

Cut cement board or foam backer board to fit the shower walls. Leave a 1/4-inch gap at the tub flange and at floor level to allow for expansion. Fasten the board to the studs using approved corrosion-resistant screws every 8 inches along the edges and 12 inches in the field. Do not over-drive the screws; the head should sit flush but not break the fiberglass mesh.

Apply waterproofing membrane over all seams and corners. Use a fiberglass mesh tape embedded in thin-set or a liquid-applied membrane over cement board. For maximum protection, coat the entire shower area with two coats of liquid membrane, overlapping each coat by at least 2 inches. Pay extra attention to the flange and curb areas. Let the membrane dry fully before tiling.

Tiling and Finishing

Layout and Cutting

Draw reference lines on the wall to ensure the tile layout is symmetric and avoids thin slivers at corners. Start tiling from the bottom, using a ledger board to keep the first row level. Cut tile with a wet saw for straight cuts and a diamond hole saw for pipe penetrations. Back-butter each tile with a notched trowel (1/4 x 3/8 inch for floor tile, 1/2 x 1/2 inch for large format). Press the tile into place and use spacers for consistent grout joints (1/8 inch is standard for walls).

Grouting and Caulking

After the thin-set cures for 24 hours, remove spacers and apply unsanded grout for joints under 1/8 inch, or sanded grout for wider joints. Wipe diagonally with a damp sponge, being careful not to wash out the grout. Let it haze over, then buff with a microfiber cloth. Wait 72 hours before applying silicone caulk at all changes of plane (corners, tub-to-wall junction, shelf edges). Caulk also around the shower valve escutcheon and showerhead arm. Use a high-quality 100% silicone; avoid caulk labeled "bathroom" or "kitchen" if it contains acrylic, as it shrinks and cracks in wet environments.

Final Touches and Accessories

Install a shower curtain rod or glass enclosure. For a seamless look, consider a frameless glass panel supported by hinges on a solid wall. If using a curtain, choose a heavy-duty fabric liner with a rustproof grommet top. Add a grab bar if needed—anchor it into blocking or use toggle bolts in tile.

Lighting should be rated for wet or damp locations, depending on its proximity to the shower spray. Recessed LED fixtures with a vapor barrier are a good choice. A wall-mounted diverter or hand-held sprayer with a slide bar adds convenience for rinsing the tub or assisting a pet.

Consider adding a recessed medicine cabinet or shelving niche in the adjacent wall for toiletries. A heater or towel warmer can also be wired into the circuit if you plan ahead.

Maintenance and Long-Term Care

Keep the tub and shower clean with non-abrasive products. Avoid bleach and ammonia-based cleaners on acrylic surfaces; instead, use white vinegar diluted with water. Recaulk the tub-to-tile joint annually or when you notice hairline cracks. If the grout starts to crumble, remove and regrout promptly to prevent water from seeping behind the tile.

Check the drain assembly for slow draining—hair and soap scum can accumulate in the overflow pipe. Use a zip tool or plumbing snake monthly. For hard water stains on the showerhead, soak the head in a bag of vinegar overnight. Replace the showerhead rubber nozzles if they become clogged.

If you notice a musty odor, inspect the backer board and subfloor for moisture intrusion. A moisture meter can help pinpoint the source. Prompt repairs prevent rot and mold, which can lead to costly remediation.

When to Call a Professional

While a confident DIYer can handle most of this project, certain tasks may require a licensed plumber or electrician: moving drain lines between joists, connecting to cast-iron waste pipes, installing a new vent stack, or adding a dedicated circuit for an inline shower heater or heated floor. Additionally, if your home has a concrete slab foundation and you need to break up concrete to relocate plumbing, a professional with a jackhammer and rebar cutter saves time and prevents structural damage.

If you live in a multi-story building or condominium, check with your HOA; plumbing modifications may require permits and professional oversight. Some jurisdictions also require a licensed contractor for any alteration that involves a wet area, even if the work is done by the homeowner.

Investing in a pro for complex plumbing or waterproofing may cost more upfront, but it protects the investment in your bathroom and prevents headaches down the road. For the right balance of time, skill, and budget, many homeowners choose to install the tub themselves and hire a licensed plumber for the final connection and inspection.

With careful planning, quality materials, and attention to waterproofing details, a tub with a built-in shower can transform a cramped bathroom into an efficient, comfortable space. The key is taking the time to get each step right—especially the leveling and membrane work—so your installation lasts for decades without leaks or repairs.

For more detailed guidance on drain sizing and venting, refer to the Family Handyman tub drain installation guide. The This Old House series on shower surrounds offers clear video walkthroughs. If you are tiling the surround, the Fine Homebuilding waterproofing guide provides best practices for liquid and sheet membranes. Finally, the Home Depot tub-shower combo buying guide helps compare models.