Build Your Own Bathtub From Scratch: A DIY Guide

Are you renovating your bathroom and looking for the perfect tub? It won’t take long to realize that most tubs are either ridiculously small or ridiculously expensive. You could have it built to size, but a bespoke fixture will likely break the bank. There is a solution, though.

You can make your own custom bathtub from wood, concrete, or stone. All you need is carpentry or construction skills, time to spare, and a handful of tools and materials based on the tub you want to build. This guide will teach you how to do it.

Is It Easy To Make Your Own Bathtub?

Building your own bathtub isn’t easy nor inexpensive. However, it is often cheaper than building a custom-size tub and definitely doable.

The project is more suited for skilled DIY with experience in carpentry or construction. You’ll also need some plumbing knowledge to build the drains and install your tub properly.

You can still build a tub if you’re a beginner, but the project could take longer, and you might find some parts frustrating. That said, read on to find how to make a wooden, tile, or stone tub.

How To Make A Wooden Bathtub

Wooden bathtubs are the epitome of elegance. They are also easier to make compared to tile or stone tubs. You could opt for a rectangular design or ask a lumber or carpenter to cut the pieces for a curved bathtub.

Things You Will Need

• Bamboo or cedar wood
• Circular saw
• Wood steamer (optional)
• Sandpaper (220-grit)
• Water-resistant wood glue
• Waterproof wood finish
• Screws 
• Butt joints
• Electric drill driver
• Measuring tape
• Paper 
• Pencil 
• Protective equipment

Step 1 – Select the desired wood type

Wooden bathtubs can add visual appeal to all bathrooms, but you can’t use any type of wood to build them. It is crucial to pick a water-resistant wood, such as bamboo or cedar. Teak is another excellent choice or, if you have the skills, you could build a bathtub from walnut, maple, or oak.

Step 2 – Create a bathtub layout

Decide what type of tub you want to make. Freestanding wooden tubs look fabulous, but you could also opt for a built-in tub surrounded by steps for a spa-like experience. Moreover, a smaller, rectangular tub could be a better choice for a small bathroom.

Measure your space and decide how big you want the tub to be. As a reference, standard tubs are 60 inches long, 32 inches wide, and about 16 inches tall. You can obviously make your tub bigger or smaller, based on your space.

Once you’ve decided the dimension, draw the tub layout on paper – you may want a round, oval, square, or rectangular tub.

Step 3 – Cut the wood to the required size

Cut the wood to the required size and shape. If you want a curved, oval, or round tub, you’ll have to use a wood steamer machine to bend the boards – if you’ve never done this before, ask a lumber or carpenter to cut and bend the wood pieces for you.

Step 4 – Build the tub bottom and frame 

Cut the bottom of the tub from a larger wood board; ideally, the bottom should be made of one piece of wood so that it doesn’t require any gluing. You can build the tub walls from as many pieces of wood as you like and glue them together.

Once you’ve cut the bottom, build the tub frame of 2-by-4 boards. Join the lumber with butt joints and screws, then assemble the tub’s wall on the frame, angling them in a way that it feels comfortable to sit in it. 

Don’t mount the bottom yet, but cut a hole where the tub drain should go.

Step 5 – Install the rough-in plumbing 

Rough-in the tub drain and faucet. When installing the drain, remember that you should maintain a slope of ¼ inch per foot of pipe from the tub’s drain hole to the point where the tub drain joins the main drain pipe.

Once you’ve roughed in the plumbing, place on the floor two layers of 19/32-inch exterior grade waterproof plywood. Cut a hole in the plywood above the tub drain so that you can connect the tub’s flange to the pipe. Fix the plywood to the floor – this layer will act as a base for your tub.

Step 6 – Cement the tub floor

The tub floor consists of the plywood layers you installed at step five. This floor is level, but you need a slope to aid the water drain from the tub. Thus, you’ll have to add a layer of Portland cement or mortar mix over the plywood, maintaining a slope of ¼ inch per foot toward the drain. Let the cement dry.

Step 7 – Install the tub

Place the tub’s bottom over the cement base and fix it with water-resistant wood glue. Let the glue dry for a few hours, then install the sides. 

Use screws to fix the sides to the bottom and apply a thin layer of glue along the joint to create a watertight seal. Wait for the glue to dry, then apply another layer of glue.

Step 8 – Treat the tub

Once all joints are sealed, and the glue is dry, treat the entire tub with waterproof wood coating. You could use a transparent coat to let the wood’s beauty shine or use a translucent varnish. 

Sand the surface with 220-grit sandpaper to improve grip and apply a coat of primer. Let the primer dry, then apply the first coat of lacquer or varnish. Let it dry and apply a second coat

Step 9 – Hook the drain and faucet 

When the topcoat is dry, install the flange and connect the tub’s drain to the drainpipe. Fix the faucet on the tub, then run the water to check for leaks.

Fill the tub with water and let it sit for at least a day. In this way, you can check the joints and make sure nothing leaks. Drain the water and enjoy the tub.

How To Build A Bathtub From Tile

Tile bathrooms look like opulent, Roman baths and could make your bathroom feel like a home spa. Most DIYers find it easier to build a concrete or brick tub and tile it rather than make a wood tub. Here’s how to do it.

Things You Will Need

• Bricks or concrete 
• Plywood (optional)
• Brick cement mix (optional)
• Fiberglass panels 
• Fiberglass glue 
• Tiles or mosaic 
• Tile cutter
• Saw 
• Measuring tape
• Protective equipment

Step 1 – Decide the tub size and layout 

Unlike a wooden tub that can be removed easily, a tile tub is a more permanent construction. This is why you should take your time to decide the tub’s size, layout, and position in the bathroom.

Step 2 – Install the rough-in plumbing 

Based on the measurements, layout, and placement decided previously, rough in the drain and faucet. Because you won’t be able to change the tub’s position once it’s built, it is essential to think things through before roughing in the plumbing.

Step 3 – Build the tub walls

You can build the tub walls with bricks or make them of concrete. In the first case, simply build a brick “wall” by arranging the bricks one on top of the other and fixing them with brick cement. 

If you want to make a concrete tub, you’ll have to build a plywood mold first. Cut plywood boards to make an empty box (only walls, no bottom or top) fixed with screws at the ends. Pour the concrete mix into the box and wait for it to dry before removing the plywood sides.

Step 4 – Build the tub floor 

Make a cement floor for your tub, maintaining a slope of ¼ inch per foot from the far end of the tub toward the drain. Let it dry.

Step 5 – Install the fiberglass and tile the tub

Concrete and brick are both porous and will eventually leak. For this reason, you must coat the tub’s interior with a fiberglass layer before installing the tiles. 

Cut fiberglass sheets to dimension and glue them to the concrete frame with resin. You should coat the tub’s walls and bottom, then seal all joints with waterproof glue.

Once the glue is dry, install the tiles both inside and outside the tub. You can use any tiles you like, but mosaic could enhance the visual appeal. Don’t forget to cut the drain hole in the tiles when installing them.

Step 6 – Install the drain and faucet 

Hook the tub’s drain to the main drain pipe and install the faucet. Fill the tub with water and let it sit for at least 24 hours to check for leaks. After this time, empty the tub. That’s it.

How To Build Your Own Stone Bathtub

Stone bathtubs are made of crushed stone bound by polymer resin and natural minerals. This type of tub is perhaps the easiest to make, as long as you have a mold.

Things You Will Need

• Fiberglass bathtub mold
• Crushed stone
• Polymer resin
• Measuring tape
• Protective equipment
• Diamond hole saw 

Step 1 – Design the tub

Following the steps explained above, measure your bathroom and decide what shape and size your tub should have.

Step 2 – Make the stone tub

Fill the bathtub mold with crushed stone, then prepare the resin mix as instructed on the package. Pour the bonding agent over the crushed stone and let it dry for the time specified on the resin package. 

Step 3 – Install the rough-in plumbing 

Rough-in the drain and faucet using the same method as explained above. Don’t forget to leave a slope to ensure adequate drainage.

Step 4 – Cut the drain hole into the tub

Cut the drain hole into your stone tub using a masonry-grade diamond hole saw. 

Step 5 – Install the tub

Position the tub in its place and install the drain and faucet. The polymer resin used as a bonding agent is already waterproof, but you can apply a lacquer finish if you want to. That’s it. You can now use your tub.

Frequently Asked Questions

Perhaps you now know how to build a bathtub, but you might have other questions. Check out the answers below.

How much does it cost to build a bathtub?

Building a tub could cost you anywhere between $500 and $10,000, depending on the materials you use and whether you need additional help or can do everything yourself.

What are tub shower combos made out of?

Most tub and shower combos are made of lightweight fiberglass or acrylic, but you could make it from concrete, stone, or wood if you want to.

Is it cheaper to build a homemade bath or shower?

Building a bath or shower yourself is only cheaper if you don’t require any additional help and use cheap or mid-range materials. If you dream of a high-end tub and require professional help in addition to what you can do, it might be cheaper to find a ready-made tub and buy it.

Do bathtubs have a weight limit?

The structure of your home generally determines the weight limit of a bathtub – an architect or builder could help you find out the maximum weight the floor can withstand. As a general rule, standard tubs weigh about 400-500 pounds when full. 

Summary

Building your tub from scratch is a challenging yet rewarding project. If you like to stand out and decorate your home with unique items, then you should definitely go for it.