Installing a bathtub on your own can be a daunting task, but also an incredibly rewarding and cost-effective home improvement project. With proper planning, patience, and by following crucial safety precautions, even novices can install a bathtub safely and correctly. This comprehensive guide will provide you with everything you need to know for a new bathtub replacement and installation from start to finish.
Bathtub Installation Planning and Preparation
Before you start ripping out walls or lugging tubs into place, careful planning and preparation is key. Rushing into a DIY bathtub installation unprepared can lead to frustrating, costly, and dangerous mistakes. Follow this bathtub installation checklist to ensure your project goes off without a hitch:
Choose the Ideal Bathtub Type For Your Bathroom and Needs
Bathtubs come in a wide array of sizes, shapes, materials and configurations. Before purchasing your tub, determine:
- Budget: Acrylic and fiberglass tubs tend to be the most affordable options, while cast iron, copper and solid surface tubs come with higher price tags. Determine how much you can reasonably spend before shopping.
- Tub capacity: Consider both the interior tub dimensions as well as its capacity to hold water. Larger tubs require more floor space and water to fill, while compact tubs may not allow comfortable bathing for larger users.
- Material: Key bathtub material factors include heat retention, ease of cleaning, durability and repairs needed over the tub’s lifespan. Porcelain-enameled steel and acrylic tend to strike the best balance across these categories for most homeowners.
- Configuration: Key options include alcove tubs, corner tubs, drop-in tubs, freestanding tubs, under-mount tubs and walk-in tubs. Make sure to select the configuration best suited to your existing bathroom layout and plumbing.
- Special features: Consider any special therapeutic or accessibility features you may desire, like massaging jets, heated surfaces, grab bars or low thresholds for walk-in access.
Inspect and Repair Subflooring
Before installing your tub, inspect the existing floor structure beneath your bathroom. Water damage or weak, unstable subflooring must be addressed or it can undermine the stability of your newly installed bathtub.
Key subfloor inspection and repair must-dos include:
- Check for water damage or soft, spongy areas on your subfloor.
- Identify areas where subfloor panels may have come loose or unattached from floor joists.
- Use an electronic stud finder to locate and mark floor joist locations.
- Check that floor joists are level and capable of supporting a bathtub filled with water, which typically weighs over 100 lbs per cubic foot.
- Reinforce, sister or replace any damaged, unstable or under-dimensioned floor joists prior to installation.
Gather Tools, Materials and Protective Equipment
Bathtub installations require an array of common power and hand tools. Make sure to gather all necessary tools before starting demo work to avoid dangerous bathtub removal delays.
Essential Bathtub Installation Tools
- Tape measure
- Level
- Adjustable wrenches
- Channel lock pliers
- Hacksaw (for cutting drain pipes)
- Utility knife
- Caulking gun
- Pry bar
- Claw hammer
- Flat pry bar
- Reciprocating saw (for tile or fiberglass tub demo)
- Rotary hammer drill (if drilling through tile or concrete)
- Personal protective equipment like goggles, gloves, knee pads, N95 mask
Key Materials
- New bathtub
- Drain assembly and P-trap
- Bathtub faucet and valve assembly
- Plumbing pipes, fittings, fluxes and solders
- Bathroom silicone, tub & tile caulk
- Galvanized roofing nails, furring strips or ledger boards
- Tub gripper pads, pliers and custom drain linkage for freestanding tubs
Turn Off Home Water Supply and Drain Existing Bathtub Pipes
Before demolition, locate your home’s main water shut-off valve and turn it off to prevent leaks. Typically located near your main home water meter, the water shut off valve turns water flow from the street off at your home’s main line.
Open all bathtub faucets to drain the remaining water from pipes and allow air entry to prevent vacuum pressure and leaks during removal.
Place a large bucket beneath the existing tub’s drain pipe to catch the remaining water exit. Have towels on hand to contain any small drips during the demo.
Create a Game Plan for Debris Removal and New Bathtub Entry
Determine your plan for sliding, pivoting or tilting your new bathtub into place before you begin demolition. With obstructions cleared, some tubs may fit through doorways while larger tubs may require window or wall removal.
Similarly, have a plan for clearing bathroom demolition debris before smashing up your old tub and surround. A wheelbarrow and tarps to contain dust and debris can simplify debris removal via nearby windows or doors.
Read More: Your Bathroom Cleaning Chemical Guide
Removing Your Old Bathtub and Surround
With preparations complete, it’s time to remove your existing tub and surround. This process entails disconnecting plumbing, demolishing tile and securely extracting the physical tub itself without collateral damage. Follow these steps to safely clear space for your new bathtub:
Step 1: Disconnect and Remove Fixtures, Drain and Water Supply Lines
Removing toilet paper holders, towel bars, shower curtains and related fixtures clears the way for demolition. Place removed hardware like faucet handles in bags for potential reuse or safekeeping.
Before smashing adjacent tiles or walls, disconnect and remove:
- Bathtub drain pipes, P-trap and overflow elbow
- Supply lines including shut off valves (capped to prevent leaks)
- Wall-mount faucet handles, valve assembly and tub spout
Tip: Scratch aligning marks on joints to ensure correct plumbing reassembly later. Photograph connections before disassembling.
Step 2: Demolish Wall Surfaces and Associated Plumbing
With fixtures cleared, use a mini-sledge, hammer and pry bar to demolish tile, drywall or fiberglass tub surround panels. Carefully demolish walls only to the extent needed for removal to simplify repairs later.
Create clear access above and around plumbing pipes. Remove or disconnect abandoned supply and drain pipes at the wall or floor level. Consider wearing goggles, gloves and an N95 dust mask for demolition.
Pro tip: For cast iron tubs with tile surrounds, consider renting a demolition hammer or rotary hammer drill to smash through surfaces while minimizing wall damage.
Step 3: Secure the Bathtub for Safe Extraction
Before attempting to dislodge the physical tub itself, brace the tub to prevent sudden crashes that can damage tubs, floors or installers.
Slide wood boards, lifts, appliance dollies or furniture sliders beneath the tub to create a sliding pathway. For freestanding tubs, tipping slowly onto a padded surface can simplify removal without damage.
Use pry bars or 2×4 boards wedged beneath lip edges to stabilize. Attach ratchet straps or rope around the tub anchored to secure pillars, joists or doorknobs to prevent sudden slipping.
Step 4: Dislodge the Tub and Remove it from the Bathroom
With bracing and sliding mechanisms in place, work cleanly around the tub perimeter to dislodge it from nails, hardware or adhesive contact points. Maintain the tub’s balance and prevent sudden twisting or toppling throughout removal.
Create an angled slide pathway using planks to roll, pivot or slide the tub out on dollies or boards. Or, lift the tub at contact points along walls or at opposite ends by two installers. Carefully work the tub through doorways, around corners or through temporary wall openings.
Preparing Walls and Floors for New Bathtub Installation
With the old tub removed, inspect the newly exposed surrounding walls and subfloor. Address any structural or water damage issues before mounting backing boards or installing a new tub:
Step 1: Inspect Subfloors and Wall Framing for Damage
Exposed wall studs and subfloor areas should be checked for levelness, water damage and material integrity necessary to support tub weight.
Use a level on walls and wood framing to determine plumpness. Shim loose wall studs with wood spacers until properly oriented vertically. Address mold, rot damage or improper floor heights before moving forward.
Step 2: Install New Blocking, Ledgers and Plumbing
Many bathtub installations require newly constructed framing structures to provide anchored support against wall studs or floor surfaces. Common tub bracing structures include:
- Ledger boards: Long horizontal boards screwed atop subfloors along which tub bottom edges can rest.
- Nailers: Vertical boards attached to wall studs and/or floor to brace tub sides.
- Corner blocking: Diagonal wooden braces installed behind tub corners for added support.
Use pressure-treated lumber sized appropriately for your tub weight (2 x 4, 2 x 6 etc.). Drill pilot holes and toenail boards into place atop flooring or behind wall stud areas blocked off by your new tub.
Rough in replacement plumbing pipes and drain lines before tub installation.
Step 3: Install Backerboard, Moisture Barriers and Drains
With framing constructed, install tub surround foundation materials:
- Cement backerboard panels covering walls to improve waterproofing and tile application later.
- Vapor barriers like painter’s plastic over wood surfaces to prevent moisture damage.
- Subfloor drains covered with hair catchers to prevent below-floor moisture.
Screw backerboard panels into wall studs. Seal all seams and floor/wall edges with thinset mortar to waterproof. Install drains per manufacturer instructions.
Installing Your New Bathtub
With demolition debris cleared and adequate structural support in place, it’s finally time to install your new bathtub!
Carefully measure for proper positioning and use shims liberally during the installation process to ensure your tub base ends up perfectly level.
Step 1: Dry Test Tub Positioning Before Permanent Mounting
Before sealing a tub into its final position along wall studs or flooring, do a “dry run” test positioning.
Carefully slide the tub part way into your bathroom, tilting it to fit through doors and clearances. Gauge positioning tightness between opposite walls, corners or alongside toilets.
Mark original planned position lines with tape or chalk. Ease the tub out and make any positioning adjustments necessary to your backing boards or framing before final placement.
Step 2: Apply Sealant and Set Tub into Position
After confirming tub positioning logistics, run a continuous high quality silicone bead along its bottom edges (allocating caulk underneath rather than between the tub and studs). Also, apply continuous vertical beads along wall stud locations or bore lines for nailers where sides will contact framing.
With a helper, gently lower and angle the tub into place atop caulked ledger boards aligned against wall studs or cross-braced floor joists. The tub backside should press into caulked wall studs marked during dry runs for even weight distribution. Carefully check for levelness on all sides.
Step 3: Secure the Tub Against Shifting
With the tub centered and pressed into position, drill guide pilot holes for screws through tub rim edges, sides or base into wall or floor anchors below. Cover holes later with escutcheon plates.
Consider using adhesives like panel bond or construction adhesive between tub and walls for added adhesion. Place shims to wedge the tub into a tightly leveled alignment against the framing as you secure.
Alternative Freestanding Tub Anchoring
For freestanding tubs placed away from walls, use plumber’s putty, silicone or molded plastic to seal tub bases against subfloors. Weigh down the tub interior or brace the exterior strategically with lumber blocks to prevent shifting.
Installing Plumbing Fixtures and Surrounds
With tubs positioned and secured, complete installation by adding faucets, supply lines and surround surfaces:
Step 1: Attach Plumbing Fixture and Accessory Mounts
Having removed wall-mount faucet handles and valves during demolition, reinstall mounts secured firmly between wall studs or atop backing boards. Attach tub spouts and shower heads directed to appropriate tub locations.
Fasten any desired cleaning accessories like soap trays, shelves or niche shampoo holders centering over the tub as desired.
Step 2: Connect Drain Lines and Trap Assemblies
Attach a trap assembly to tub drain lines, curving pipes appropriately to meet downward through subfloor drain routes. Add tub overflow elbows and route to meet main drain lines below floors or behind walls.
Tip: When cutting or attaching drain pipes, maintain overall downward slope gravity flows.
Step 3: Run and Pressure Test Water Supply Lines
Measure and cut replacement copper, PEX or PVC pipe between tub valve inputs and bathroom water supply lines. Solder copper joints carefully using fluxes and sand cloths.
Use elbows and T joints to deliver separate lines to the tub spout, shower head and faucet inputs based on your fixture layout. Ensure all lines are anchored securely along runs to prevent leaks over time.
Turn the home water supply back on (capping any unconnected lines during testing). Check for immediate leaks at nearby connections before covering with finishes. Consider pressure testing lines for 12-24 hours capped before finishing the installation.
Step 4: Install Wall and Surround Finishes
Apply water-resistant drywall, greenboard or backerboard across wall areas surrounding your tub. At seams and floor edges, maintain waterproofing from tub install stages.
Finish by tiling, or adhere one-piece tub surround fiberglass or acrylic surround paneling. Use silicone caulk between panels and where surrounds contact tub rims for flexibility and water protection.
Common Bathtub Installation Issues and Solutions
Even if all preparation and installation steps are completed carefully, adjustments may be needed over time as homes and tubs shift:
Tub Leaking Issues
Leaks typically occur at pipe joints or connections. Check for cracks or separated caulk beads between the tub and walls or surrounds. Recaulk with silicone sealant. Replace worn gaskets or washers in faucet assemblies.
Drainage Problems
Clogged hair catchers can block subsurface drains. Flush with drain snake monthly. Check trap assemblies for snug fit without leaks. Confirm gravity flows downward on all drain line routes.
Noisy Pipes or Faucets
Loose pipes or valves can develop loud banging noises over time, especially with higher water pressures. Tighten loose mounts, refasten pipes or replace compression gaskets to reduce echoes. Consider pressure-reducing valve installs where pressure exceeds 80 psi.
Shifting Tubs
Improperly shimmed, anchored or weighted tubs can gradually shift out of level. Check for gaps behind tubs. Recaulk and install additional ledger boards, L brackets or plumber’s tape strips to reinforce stability.
Mildew Growth
Standing moisture fuels ugly mildew spread on grout, caulk beads or tile edges. Improve bathroom ventilation. Routinely apply spray cleaners containing bleach or tea tree oil to deter growth.
Conclusion
We hope this comprehensive DIY bathtub installation guide has equipped you to tackle a bathtub replacement or upgrade with confidence. While the demolition work takes time, new installation with proper planning can typically be completed over a focused long weekend.
The upfront effort pays dividends for years through added home functionality and thousands of dollars saved over contractor costs. Just be sure to gather tools, brace old tubs for safe removal and take a methodical approach to new tub installations.
With some sweat equity, you can enjoy a like-new bathtub installation that will provide enjoyment and elevated home value for decades to come!