Make Bathtub Deeper: 8 Tested Extension Tips

We all love a soaking bath after a stressful day, but what if you have a standard tub instead of a soaker one? Sitting around in a puddle of water is no fun, so perhaps you’re looking for ways to make your bathtub deeper

Bathtub liners give you a quick and easy way to make your tub deeper permanently. You could also build a fiberglass tub extension yourself or use an overflow stopper. Covering the overflow is the most cost-effective solution, but you risk creating a mess if you forget the faucet open.

Why Are Bathtubs So Small?

While soaking in a big bathtub at home is sometimes better than the spa, the reality is that most houses have small tubs. Why is that, though?

There are several reasons why builders and tub manufacturers prefer these dimensions. Perhaps the most important reason is the average height of the people using the tubs. In the US, the average adult height is 5-foot 9-inch for men and 5-foot 4-inch for women. Europeans are slightly taller, but the average bathtub size would suit them too: standard tubs are 60 inches (5 feet) long and 32 inches wide.

In a tub this size, people won’t risk drowning if they fall asleep while taking a bath. Thus, safety is one of the main reasons bathtubs are so small.

Water-saving is another motive. It is quite clear that you’ll need more water to fill a large tub. A small tub will not only help you save on utility bills but is better for the environment.

Lastly, builders and interior designers prefer smaller tubs because they are compact and allow for better optimization of the bathroom space. Moreover, small bathtubs are also easier to install compared to their larger counterparts.

Despite these motives, the main reason why you might like a big tub is that it allows you to soak all of your body (without having your shoulders or feet out of the water). Instead of shopping for a new tub, however, you could make the one you have deeper. Here are a few ways to do that.

How To Make An Existing Bathtub Deeper: 2 Height Extenders

The main difference between a standard and a soaker tub is the water depth. This refers to the tub’s height from the bottom of the tub to the lower edge of the overflow. Standard tubs have a water depth between 14 and 16 inches. Soaker tubs boast a depth between 24 and 30 inches. While extending your tub’s height won’t give you so many extra inches, you could up the water depth to 19-20 inches using the methods below.

1. Install a Tub Liner 

A bathtub liner, also called bathtub overlay, is an insert fitted over an existing bathtub to increase its height. The liner will reduce the tub’s length and width by a couple of inches, but it will transform your standard bath into a soaker one.

The tub liner’s main advantage is that it allows you to transform your bath without messes. You won’t have to remove the old tub to install a soaker one, which means less fatigue. 

An overlay is also less expensive than replacing the tub – but this doesn’t mean that it’s cheap. On average, you can expect to pay between $1,580 and $3,230 for the insert and labor. In comparison, a new tub plus installation can cost you anywhere between $3,000 and $6,000, depending on where you live and labor rates in your area.

Tub liners come in various sizes and heights, as well as a variety of materials, including fiberglass, acrylic, and polystyrene. 

When choosing the right insert, remember that the liner can crack or grow mold and mildew if it doesn’t fit properly on the tub.

2. Build a Tub Height Enhancer 

Bathtub liners provide homeowners with a quick and easy solution for making an existent bathtub deeper. However, if you’re more of a DIYer and wouldn’t want to spend too much, you can build a tub height enhancer yourself.

Tools and Materials 

  • ½” plywood 
  • ¼” fiberglass 
  • Fiberglass resin 
  • Automotive spray paint
  • Foam gasket
  • Silicone caulk
  • Circular saw
  • Sandpaper 
  • Goggles 
  • Rubber gloves
  • Face mask with respirator
  • Tape measure
  • Brad nailer
  • Plywood nails

Step 1 – Measure the tub and plan the height enhancer layout

Before building a height enhancer, you must measure the tub and write down the size. The height enhancer must go directly over your tub’s edges, so if your tub doesn’t have a rectangular shape, you should draw the layout on cardboard (at real size) for easier cutting and assembling of the pieces.

Step 2 – Build a plywood frame

Cut the plywood boards to size using the dimensions you just measured. For instance, if you have a standard tub (60 x 32 inches), you need two 60-inch long pieces and two 32-inch pieces. The height of each piece depends on the total height you want your tub to reach, but remember that getting in and out of a tub that’s too tall can be uncomfortable. 

Once you have all pieces cut to size, assemble them to create a frame. You can use plywood nails or wood screws (in this case, you’ll need an electric drill driver, too). 

Step 3 – Cover the frame with fiberglass 

Cut several pieces of fiberglass in both sizes and fix them to the plywood frame with resin. Let each fiberglass layer fix as instructed on the resin package before adding a new layer. Two or three layers should suffice. 

Once you’ve done that, measure the interior of your frame and cut other fiberglass pieces to dimension. Install them on the interior of the frame as you did on its exterior.

Let the frame dry for about 24 hours before proceeding to the next step.

Step 4 – Paint the frame

While fiberglass is waterproof, plywood isn’t. You’ll have to waterproof the frame on all sides to prevent it from becoming a home for mold and mildew. 

The easiest way to do that is by painting it with automotive paint (in your tub’s color). Move the frame outside and place it on sawhorses. Lay a drop cloth underneath it and spray paint it. Let the first coat dry, then apply a second coat. Paint all sides, including the lower and upper edges.

Step 5 – Install the height enhancer 

Fix a layer of foam gasket to the tub’s edges with silicone caulk and let it dry. Once the gasket is fixed, apply a thin layer of silicone caulk on top of it and place the height-enhancing frame on top of it. Press gently to make the surfaces adhere, then let it dry.

Once the frame is fixed, apply a further layer of silicone caulk on the inner and outer joint between the frame and the tub. In this way, you can make the structure impermeable and won’t risk getting out of the tub in a puddle.

All you need now is an overflow stopper to start enjoying your makeshift soaker tub.

DIY: How To Stop The Overflow Drain In A Bathtub

Whether you want to build a tub height enhancer or simply fill your bath to the brim, you can do so with an overflow drain stopper. Here are a few ways to block the overflow.

1. Use a plastic overflow cover 

Plastic overflow covers offer a simple solution when you want to fill the tub higher. These covers feature suction cups and can be placed over the overflow drain or removed as needed.

2. Use moldable glue 

Moldable glue isn’t designed to use in the tub, but the stuff becomes waterproof once dry. If you have an older tub with strain overflow, you can use moldable glue to fill the holes. Let the glue dry for 24 hours before using your tub again.

This method works well and is reversible, but you may have a hard time removing the glue from the strain holes. If the glue falls down the drain, it could also clog your pipes.

3. Install a permanent overflow plate 

Permanent overflow plates aren’t exactly permanent, in that you can remove them and replace them with a tub drain. However, they require you to unfasten the overflow drain and replace it with a ceramic or chrome plate. Fix the plate with screws, seal with silicone caulk, and you can enjoy deep baths.

4. Use caulk strips 

Another temporary solution, caulk strips, allow you to cover and uncover the overflow as needed. Just keep in mind that the strips might not hold up for the whole time you’re in the bath.

5. Block the flow with hair ties 

Hair ties don’t offer you a permanent solution and won’t work on all overflow types. However, if your tub has a modern overflow plate, you can slip a few rubber hair ties over it to create a makeshift seal. This solution will prevent the tub from emptying too fast, but leaks may still occur.

6. Mount the overflow upside down

Another DIY solution tried and tested by homeowners is to unmount the overflow drain and install it on the opposite side. Seal the edges with silicone caulk to create a leak-free solution.

Related Questions

Do you still have questions? Find out the answers below.

How much does it cost to put in a deep tub?

Replacing the bathtub is generally an expensive affair, with prices ranging from about $3,000 to $6,000 on average. These prices include the cost of the new tub, materials, and labor. However, you could spend less if you have a freestanding tub and want to replace it with a deeper freestanding model.

What height should a bathtub be?

Standard bathtubs have a height between 14 and 16 inches. Most soaker tubs are taller than 24 inches, allowing an adult to soak their entire body. At that height, however, you might have to build one or two stairs around the tub for an easier in and out. 

What is a good soaking depth for a tub?

A good soaking depth is between 20 and 24 inches for most adults. If you are particularly tall, you may find a 26-30 inches tub more suitable for you.

How much water can a bathtub hold?

Standard bathtubs can hold about 42 gallons of water when filled to the brim. However, most people use about 30 gallons per bath.


Making your bathtub deeper isn’t hard or troublesome. There are various solutions, from permanent to temporary ones. Decide which works best for you based on your needs and budget.

Have you tried any of the methods above? Have they worked for you? Tell us in a comment.

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