Wood Bathtub

Woodworkers constantly try new and fancier ideas and ways to use their materials to improve our homes and lives. Even so, one room of the house has defied the attention of woodworkers: the bathroom. It seems that bathrooms are not all that conducive to wood and ideas, perhaps because of all the water in them. Water and wood in baths aren’t a great mix.

Nevertheless, some inroads are being made into this sanctum space as woodworkers find better ways of waterproofing their projects. We see this mainly in the bathroom sinks and vanity countertops of luxury, where natural edge wood slabs are finding their way into fancier homes. But a wood bathtub is the ultimate luxury of putting wood into your bathroom.

Cost of Wooden Bathtubs

Wood bathtubs can run for upwards of $30,000, making them some of the most expensive wooden or copper bathtubs on the market. You can spend more buying something carved out of solid crystal or marble. But it is possible to make your wood bathtub. While most of us cannot carve a two-ton piece of crystal or copper, wood bathtubs are, in part, even if we could find one to carve.

Kinds of Wood Baths

To clarify, there are three different things that you can refer to as “wood bathtubs:”

  • A Japanese-style deep wood hot tub 
  • A freestanding bathtub made of wood (essentially a modification of the Japanese hot tub, in the shape of an old-fashioned freestanding bath)
  • A laminated hardwood tub

Compared to the laminated hardwood tub, the other two bathtubs are cheap. You can buy them for a few thousand dollars. You can even find them for sale at your local building materials center. These are “natural wood” tubs made out of wood that can withstand decay (cedar, walnut, or rubber wood) caused by water. The laminated hardwood tubs are made of hardwoods by only one company, NK Woodworking and Design.

Either the style of the laminated wood tubs or the freestanding ceramic found at the home and bathroom centers are much like a barrel, with staves fitted together and banded to hold them in tight contact. NK woodworking’s wooden bathtubs are made more like a ship, as the founder, Nathie Katzoff, got inspired for his start in woodworking by learning boat building.

Yet both types of tubs are installed in your bathroom just like any other shower or freestanding tub would be installed. All you have to do is set the tub in place, then connect the faucets and drain. It’s easier than installing a built-in tub.

Can You Make Your Own Wood Bathtub?

Of course, you can!

Since you’re on this website, I assume you’re asking yourself the same question I asked myself – can you build your collection of wooden bathtubs on your own? Looking at the price and quality of the finished bathroom tubs from the NK woodworking site and Design, I would have to say yes, but it will take a lot of time. While I haven’t seen them build one, I can see how it would have to be built, especially assuming that the artist is working from a background of building boats.

Steps on How to Make a Wooden Bathtubs

To start with, you’ll need a framework. Any boat I’ve ever seen built starts with a framework. In this case, the framework won’t become part of the finished tub but will help in the layup and gluing of the tub. To work, it needs to follow the inside contour of the finished tub, keeping in mind that the final dimensions of the inside of your tub will be slightly larger than the dimensions of the framework. Once laid up and glued, the final contour will be created by planning and sanding the tub’s interior and exterior.

I would recommend waxing the outside of your framework so that the glue from laminating the layers of your tub together can’t stick to it. It would be possible to break the framework and then clean up any scrap from the inside of the shower tub, but waxing the framework will eliminate the hassle of doing this, saving you time.

Working from the bottom up, you’ll want to assemble the base first, shaping and gluing the pieces together and setting them on your gluing bench. I’d recommend using some template or jig to hold them in place to ensure they don’t move as you add additional layers.

The following piece is the floor of your tub. This is flat, assembled by joining ¾” planks, much like making a tabletop. I would recommend using dowels or biscuits when assembling this for added strength. Once laminated, please attach it to the base, ensuring it is properly centered.

With the tub floor attached to the base, the easy part of the project is completed. It is now time to start laminating the sides. If your tub has tapered sides, each layer must be cut differently, as each layer will be slightly larger than the one below. The layers are cut oversized, with extra material to the outside and the inside (which sits up against your framework to give you a good reference for shaping the tub), leaving that material for final shaping.

Traditional wood bath, inside shot

As with boat building or laying a hardwood floor, it is necessary to stagger the joints from one layer to another. Even so, making the long sides with fewer joints will be easier, as they won’t be necessary. More joints will be needed at the ends due to the curvature running out of the sides of the boards.

It would be helpful to make cardboard patterns for each layer as you go to avoid wasting material. The pattern can be taken off the layer below and suitably modified to keep it in contact with the framework at all points. Depending on the complexity of the overall design of your tub, curves cut out of thin plywood can be used as patterns for the corners, as the curvature of the corner will stay consistent in some designs.

Two layers of wood planking can be laminated and cut out on the band saw to make the needed size. It will be necessary to verify that the four to six pieces that make up a layer fit snugly together, without any gaps, before installing them to create the tub.

Clamping the tub as you build it up is another challenge to overcome. The secret here is to use wood bridges over the top of the added layer, with bar clamps going from there to create the bottom side of the bathtub benchtop. You may need some help clamping to tighten both sides of the bridge simultaneously.

Keep each layer clamped until the glue has a chance to dry. This will, of necessity, make this a prolonged project to complete, as it will take longer for the glue to dry than to cut the next layer of parts to install.

Luxury Bathtub

While you can make your tub wooden bathtubs of any shape you want, most luxury bathtubs are built with a slight taper and rounded ends, bottom, and corners. This isn’t an absolute requirement for luxury bathtubs, as there are modern tub styles that are squared off. NK Woodworking and Designs even have them.

Shaping the Tub

With the glue-up of the whole bathtub tub completed, the final shaping must be accomplished. You will need to carve the final form of the tub from the rough glue-up you have made. Layers must be blended into each other, as the overall thickness of the tub’s sides is brought down to roughly an inch.

Ensure you drill the appropriate holes for the faucets and drain before you get too far along in the bath and shaping process. If you wait until you have the bathtub shaped, you may end up with chips from a hole saw to deal with. You’re better off doing that earlier in the week during the shaping process, so you can smooth the edges of those holes as you shape and sand the bathtub.

Several different tools can be used for this shaping process, depending on what you have available in your workshop. Some possibilities include:

  • A chainsaw cutting wheel mounted to an angle grinder
  • A spokeshave (a bit small, but possible)
  • Wood planes (there are planes with curved soles, which could be used for the inside of the tub)
  • Mallet and chisels 

Most likely, you will find that you will need to use a combination of different tools, as they vary in function as you work over the tub, smoothing it inside and out. Once the final shape is completed, the tub must be sanded, starting with coarse-grade paper and gradually moving to finer and finer grades.

wood bathtub, wooden

Wood bathtub, Indo Gemstone

Finishing the Tub

A proper finish must be applied to the tub to protect the wood from water damage. For this, we can take a page from the playbook of those who make the stunning luxury, natural edge, wood slab countertops. They use a thick epoxy coating for their finish because it is waterproof and durable. It is possible to tint the epoxy, as is done with “river” maple countertops, but to enjoy the wood’s full natural beauty and warmth. You’ll probably want to leave it clear.

Since you will be working without a mold, you’re better off with a heavy-bodied epoxy with a high viscosity than a thinner epoxy, leaving you with runs in your finish. The heavier-bodied the epoxy is, the faster it will build up a finish. But it will also make it more extensive and more complicated to hide runs if you are not careful.

Having worked with this sort of epoxy on a curved surface like this before, I can tell you that the trick is figuring out how thick a coat you can apply without the coat starting to sag and run. You’ll also need to keep track of the time because you don’t want to try to use the epoxy once it starts to set up, as the gel-like consistency will tend to leave lumps in your finish.

It is probably better to use an epoxy with a short set time so it doesn’t have much time to run. But this will require that you mix your epoxy in small batches, no more than you can work with, in the space of time you have before it begins to gel. Don’t worry. You can always mix more.

Each coat of finish must be sanded lightly to remove any sags and give it a rough enough surface for the next coat to adhere to. How many total coats you go for will depend on you and how heavy-bodied an epoxy you use. I would recommend a minimum of 20 coats on the inside and at least 10 on the outside.

If you look at the pictures on the NK Woodworking and Design website, it is clear that they use a lot of coats of finish on their tubs, although it is not clear how many total coats they have.

Nevertheless, considering the amount of work it takes to make this sort of bathtub, you don’t want to short-change yourself. While epoxy is waterproof, it is only if an unbroken film exists. Any pinholes in the finish or dents after the tub is installed will ruin the waterproofing, giving water access to the wood beneath.

To Avoid the Damages

With that in mind, special care should be taken when moving or installing the tub to ensure the finish isn’t damaged. Even the smallest of dents could have dire results on the quality and longevity of your tub, causing the finish to fail long before it should.

Having never owned a $30,000 bathtub, I can’t tell you how long the finish will last before the tub is refinished. You will want to keep an eye on the finish, ensuring it doesn’t become damaged and the wood doesn’t become exposed. Adding additional coats of finish over the existing finish is much easier if you can manage to do it before there is any damage to the existing finish or the substrate it is on.