The Anatomy of a Bathtub and How to Install a Replacement

Learn all about bathtubs including how to remove and replace one.
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Subway Tile with Dark Grout in Bathroom

Subway Tile with Dark Grout in Bathroom

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Bath Crashers

Photo by: Sarah Wilson / Getty Images ©2014, Scripps Networks, LLC. All Rights Reserved.

Sarah Wilson / Getty Images, 2014, Scripps Networks, LLC. All Rights Reserved.

Bathtub dimensions can vary. Before you buy, check the dimensions of a new tub so that it will fit in the same spot as the old one. Another consideration with very large tubs is whether you will be able to maneuver it through your home to the bathroom. Room to work is also important — especially in smaller bathrooms. It will sometimes be necessary to remove the other bathroom fixtures in order to remove an old bathtub and install a new one.

Anatomy of a Bathtub

Connecting the water supply to a bath is much the same as for a basin. The main difference when installing a bath is that it may be large and heavy, and access to the plumbing can be difficult.

Cast-Iron Bathtubs

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©2007 Dorling Kindersley Limited

2007 Dorling Kindersley Limited

Bathtub Plumbing Overview 01:44

Amy demonstrates the process of plumbing a bathtub drain and overflow.

Decorative cast-iron tubs may be candidates for reclamation. If not, these heavy items can be broken up using a sledgehammer and all of the material recycled. When you do this, drape a drop cloth over the old tub to stop flying debris and be sure to wear protective goggles, ear protectors and gloves.

When installing a cast-iron tub, ensure that its weight is evenly distributed across several floor joists. Planks of wood underneath the tub feet can help spread the weight. In some cases, you may need to reinforce the joists below.

Removing a Bathtub

Before you begin, make sure you have enough room to fit the bathtub through the doorway. Turn off the water supply. After the water has been turned off, open a faucet below the tub level to drain the water supply lines. Remove the faucet, the drain, and the spout. If your bathtub is sandwiched between two walls, with the faucet and shower head located on one wall, you may be able to disconnect the piping and then pull the tub out. If this doesn’t work, you may have to remove a section of the wall around the bathtub, cut the piping, and remove the bathtub through the wall. If your bathtub is freestanding, removal is somewhat easier. After disconnecting the piping, you should simply be able to lift the tub out.

Installing a Bathtub

Before installing a new bathtub, make sure that your selection is an exact fit into the old bathtub space. Make sure it is apron-styled or drop-in, and that the drain is on the same side, because bathtubs can have right-hand or left-hand drains. If the bathtub is not an exact fit, the piping will have to be modified for the new bathtub. If it is an exact fit, you’ll follow the same steps for removing the old bathtub, just in reverse. You may need to repair the wall surface so it rests on the flange of the new tub. Always use cement backerboard under tiles in the bathtub or shower areas for moisture protection and to prevent a possible mold problem. Regular drywall is not rated to handle extreme moisture.

Measuring the Position

Measure and mark the location of the bathtub's ledger (Image 1).

Attach the ledger board, which will support the bathtub’s ledger (Image 2).

Connecting the Drain

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

While the tub is on its side, dry fit the drain and water supply pipes (Image 1).

Install the rubber gasket on the bathtub overflow tube, and attach it to the tub (Image 2).

Use the fittings provided to attach the stopper retaining bracket (Image 3).

Apply a ring of plumber's putty around the drain flange (Image 4).

Attach the drain to the bathtub, using screws to secure it in place (Image 5).

Connect the Stopper

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Use needle pliers to connect the stopper chain mechanism to the stopper fit (Image 1).

Route the chain from the stopper fit through the bathtub, adjacent to the retaining bracket (Image 2).

Secure the stopper fit in place using the fittings provided (Image 3).

Lift the bathtub in place and insert the drain and water pipe assembly into the drain (Image 4).

Securing the Tub in Place

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Nail the flange to the wall studs (Image 1).

Make sure the bathtub is level, then finish the surrounding walls (Image 2).

Adjusting the Stopper

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

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Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

With time and use, a bathtub stopper may cease to block the water flow efficiently. Remove the stopper face plate from wall.

Expose the mechanism and then adjust the chain to fit.

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