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How to Install a Bathtub: Step-by-Step Guide

Nobody wants a moldy old bathtub, so here’s a step-by-step guide on how to install a new one.

Bathtubs are the centerpiece of a bathroom, and they play a key role in creating the room’s overall appearance. However, they shouldn’t only look good, it is also essential that they are installed properly to prevent leaks and ensure proper drainage.

Installing a bathtub can seem daunting but it isn’t beyond anyone with a decent amount of DIY experience. Still, there are some important things to keep in mind to ensure bathtub installation goes smoothly.

In this article, we will explain the different types of bathtubs you can choose from and how to uninstall your existing tub. Then, we will walk you through how to install a new bathtub.

Key Takeaways

  • Choose the right bathtub material: Popular options include porcelain on steel, fiberglass, acrylic, cast iron, Americast, and cultured marble.
  • Remove the old bathtub carefully: Turn off the water, remove connections and fixtures, and remove the surround before taking out the tub.
  • Install the new bathtub properly: Follow specific installation steps for acrylic, fiberglass, steel, cast iron, or marble bathtubs, and ensure proper support and sealing.
  • Consider installing a bathtub surround: This optional extra can enhance the appearance and functionality of your new bathtub, but requires careful installation and sealing.

What Are Your Options?

It goes without saying, but before you can install a new bathtub, you need to have purchased one. If you already have, you can skip this section. If you haven’t, however, keep in mind that some materials are more durable, and other finishes are more beautiful.

Here are the most popular bathtub materials used today:

  • Porcelain on Steel (PoS): These tubs are usually easy to install and are among the least expensive options. They are made of solid steel and then coated with porcelain.
  • Fiberglass: Fiberglass is also an inexpensive option. These tubs are very light, which makes installation easier, but their finish will fade over time.
  • Acrylic: These bathtubs are made from heated acrylic that is pulled over a mold. The acrylic is vacuumed tightly and then reinforced with fiberglass and resin. They are easy to clean and usually durable, but there are sometimes thin areas caused by the acrylic being pulled too tight during manufacturing.
  • Cast Iron: Cast iron tubs are among the heaviest types, so it is usually best to hire a professional to install them for you. They are great if you want a traditional or simple bathtub, but they rarely have the cutting-edge features of some other types.
  • Americast: Americast was created by American Standard and is a lighter alternative to cast iron. Despite weighing far less, it provides the same durability and heat retention as a cast iron tub (1).
  • Cultured Marble: Marble is typically the most expensive of these bathtub materials. It is also the most challenging to install and maintain, but it does provide an unmatched sense of high-end style.
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How to Remove an Old Bathtub

If you need to remove an old bathtub before installing your new one, it is important to complete these steps in order to avoid flooding your home:

  1. Turn the water off: Shut off your home’s water supply to ensure you don’t make a mess. Once the water is shut off, open your bathtub faucets to ensure the lines are completely drained.
  2. Remove the connections: Use a screwdriver to remove the faucet. You will then need to use your tools to remove the handles, overflow drain cover, and drain cover at the bottom of the bathtub. There might be plastic covers on the screws that need prying off in order to access unscrew them. If you are happy to keep your faucet and other parts, you should be able to reuse them as long as you are careful.
  3. Remove the surround: Once the extra pieces are removed, you can go ahead and start removing your bathtub’s surround. Depending on your bathroom design, this could be a tub surround or the surrounding area might be tiled. This might seem like a major step, but you will need access to the wall studs in order to install your new unit.
  4. Locate the plumbing: At this stage, you need access to your bathtub plumbing. Depending on how your home’s plumbing is configured, your pipes might be accessible from the room adjacent to the bathroom. Alternatively, they may be embedded in the floor beneath your old bathtub. You might need to cut a hole in your wall or floor to accomplish this.
  5. Remove the tub: You can finally remove the old bathtub. Unscrew the drain and overflow, then remove the tub. If it is made of acrylic or fiberglass and you intend to recycle it, you can cut it into pieces with a jigsaw to make it easier to remove from your home.

Quick Tip

If you have a tub surround, you can use a utility knife to cut along the outer drywall, then use a pry bar to pry the surround forward. Be mindful of any pipes or wires that may be inside the wall. It is easiest to work from top to bottom during this step.

How to Install a Bathtub

Once you have removed your old bathtub and acquired a new one, it’s time to install it. Before you replace a bathtub, to ensure the process goes as smoothly as possible, make sure you have the following tools to hand:

  • Screwdriver
  • Wrench
  • Pry bar
  • Utility knife
  • Jigsaw
  • Measuring tape
  • 2 x 4 wooden board
  • Level
  • Caulk

Each type of bathtub will have its own installation process but they are generally quite similar. Still, it is important to know the differences and follow the steps for your specific bathtub type.

How to Install an Acrylic Bathtub

Most acrylic tubs come in a standard size, but double check the measurements before you install it. Once you are confident that it will fit your chosen space, follow these steps:

  1. Inspect your floor for damage: Before installing a new tub, make sure the floor where your previous tub was located hasn’t been damaged. If it has, fix it before installing the new tub.
  2. Adjust the tub supports: An acrylic tub needs to have its legs adjusted properly to encourage the water to run into the drain. This means the supports at the end nearest the drain should be slightly shorter than the others. This will ensure that gravity moves the water toward the drain when you empty your bath.
  3. Connect the plumbing: Try not to fit your pipes too close together, if possible. If there isn’t much space between them, it can be more difficult to perform maintenance without removing other pipes.
  4. Install your siding: Most acrylic bathtubs will need siding to complete the overall look and complement the rest of your bathroom’s decor. The siding will need to be watertight to prevent water from seeping into it and damaging your floor.
  5. Apply sealant: Once everything is in place, finish the installation with sealant. Sealant should be applied where the bathtub meets the wall and every other edge. You should allow the sealant to dry for 24 hours before using your new tub.

How to Install a Fiberglass Bathtub

To install a fiberglass tub, you should follow these steps:

  1. Install a ledger board: This will support the back of your tub and keep it level.
  2. Check plumbing and replace if necessary: When you have an opening in your wall, take the opportunity to check your plumbing and replace any parts that need it. This will prevent you from having to access your wall again in the near future.
  3. Install the overflow pipe: Attach the pipe to the tub before you install the unit. Apply putty around the strand piece to secure it and prevent leaks. Place your gasket on the other side and twist the drain until it is secure.
  4. Install the stopper: This will plug the drain. Feed it through the pipe and then screw the topper into place.
  5. Install the bathtub unit: Place your new bathtub into its designated area and check that everything fits properly. Once you are sure everything is in order, screw it into place.

How to Install a Steel, Cast Iron or Marble Bathtub

Installing steel, cast iron, and marble bathtubs is a practically identical process. However, keep in mind that marble bathtubs are significantly heavier than the other two, so you will need some assistance to install one safely.

  1. Dry-fit your tub to ensure it fits: Set the bathtub in its installation location to check that it fits properly. You should also double-check to ensure that all drain holes line up before you install it properly.
  2. Add support: If the tub will be placed against a wall, make sure there is sufficient support to hold its weight.
  3. Attach the drain: Before installing the tub, attach the drain to make installation more straightforward. You should apply plumbers putty to the bottom of the filter to help secure it.
  4. Connect your overflow drain: Feed the trip lever stopper through the drain and use a screwdriver to secure the cover to the inside of the tub.
  5. Secure the tub: Finally, secure your new bathtub in place and use a bathtub caulk and high-quality sealant to finish it off.

How to Install a Bathtub Surround

Depending on your bathtub model, a surround might be an optional extra or an essential part of the installation. Inset baths in particular are often designed with a surround in mind. If you plan to install a surround, it is a relatively straightforward process:

  1. Remove fixtures and clean: Any dirt or other impurities can prevent the surround from fitting snugly. Take the opportunity to clean the area thoroughly as it will be more difficult after installation.
  2. Create a template: This will help you know the location of each hole and fitting. You can do this using a piece of cardboard.
  3. Transfer your markings: Transfer any markings on your template to the area where you’re installing your tub. Then, you can cut any necessary holes.
  4. Dry-fit your panels: This will help you ensure that everything has been measured and cut correctly.
  5. Attach the unit to the wall: To do this, use a strong tub surround adhesive. Press firmly on each panel to make sure they are secure.
  6. Replace all fixtures: Either reinstall your old fixtures or install your new ones, if you are replacing them.
  7. Check for leaks: Caulk any joints to prevent leaks. Allow the adhesive to set for as long as the manufacturer recommends before using your tub/shower (usually 24 hours). This will ensure the adhesive has dried properly before it gets wet again.

Quick Tip

The adhesive should be applied as one continuous line to ensure it is strong and watertight.


What is the Easiest Bathtub to Install?

The installation of an alcove bathtub typically ranges from approximately $250 to $600, based on the material and structure, making it the type of tub that is both the easiest to install and the most budget-friendly option.

Because of the space-saving capabilities of this design, alcove bathtubs are frequently installed in homes as part of shower-tub combinations. These tubs are built to fit within an enclosure with three sides and were constructed specifically for the tub.

It is a specialized kind of bathtub that many people who own their own homes are used to seeing, and it is beneficial when thinking about standard bathtub dimensions in a constrained space.

How Long Does a Bathtub Last?

The lifespan of a bathtub ranges from 10 to 30 years, depending on the tub’s construction. Tubs constructed from modern materials like fiberglass and acrylic are inexpensive and have a lifespan of 10 to 15 years.

A porcelain-enameled cast iron tub can last significantly longer, but the tub will need to be refinished every five to fifteen years.

How Do You Know What Size Bathtub to Buy?

Choose the size of the tub based on how much space you have available in your bathroom and how comfortable you want to be when taking a bath. Most bathrooms will fit a 60 x 32 x 18-inch alcove tub

Standard alcove tubs have exterior dimensions of 60 inches in length, 32 inches in width, and 18 inches in depth. Even small bathrooms usually have enough space to accommodate a tub this size.

The size of the inner basin can change depending on the tub surround thickness. It typically measures 55 x 24 inches at the top of the basin. These dimensions decrease to 45 x 22 inches at the bottom of the tub due to the gentle slope of the tub walls.

The exterior dimensions of extra-large alcove tubs are often between 72 inches in length, 36 inches in width, and 20 inches in height. These dimensions offer ample space for virtually everyone who takes pleasure in taking long, peaceful soaks in the tub.

How Long Does It Take to Install a Bathtub?

The time it takes to install a bathtub fluctuates based on potential requirements, like if you need to change the pipes or redo/install tile around the tub.

How Much Does It Cost to Install Tub?

According to Home Advisor, in most cases, the cost of installing a bathtub is $7,197. The pricing range, which considers labor and supplies, often falls between $4,131 and $10,765.

You can spend as little as $600 or as much as $14,000 on this endeavor, depending on how difficult the task is. The overall cost is determined by the kind of tub and the extent of the work to

Which is Better: Acrylic or Porcelain Bathtub?

In general, acrylic is a material that makes for a far more versatile bathtub than porcelain does. There’s debate as to whether it’s more durable, better at retaining heat, and whether or not it offers significantly greater design and stylistic flexibility.

Acrylic is the material advised for your bathroom if you are not wed to the traditional aesthetic because maintenance and repair costs are comparable for acrylic and porcelain. Still, acrylic is typically less expensive than porcelain.

Give Your Bathroom a Facelift

Replacing your bathtub can rejuvenate a tired-looking bathroom, or serve as the centerpiece of a new build. You will need to choose the right bathtub and ensure it is installed properly.

This is one area where appearance and quality will both be affected heavily by the installation work. Bathtubs come into frequent contact with water, so a snug fit and proper sealing will prevent the buildup of mold and water damage to your home.

Take your time and follow each step carefully. DIY bathtub replacement isn’t an overly complicated task but, if you aren’t particularly confident in your abilities, remember that you can always leave the task to a professional instead.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.