DIY Wooden Bathtub

I wanted a small bathtub for my small wooden cabin. It turns out small bathtubs are really expensive so I made one from a big plastic tank and some scrap wood panelling. I loved the result and it's now in use for one year and a half and it works great, plus it's surprisingly comfortable!

For this project you will need:

• 1 big plastic tank (this one is 220Lt)
• Tongue and groove wood paneling
• Wood paneling invisible clips
• Pencil
• 30un. 8mm wood dowels
• Around 40 Screws
• Wood glue
• A piece of 20mm thick plywood (the same diameter as the tank rim)
• 10 pieces of 2x8x30cm wood for the wood rim.
• 1 Drain
• Silicone sealant
• Woodworking tools such as a power drill, table saw, jig saw, angle grinder and sander.
• Marine Varnish (matte finish) and brush.
• Cement mixture
• Water
• bucket and spatula for the cement

I went to the hardware store and sat inside every tank available. I ended up choosing this 220Lt one. It's perfect for sitting inside and laying back. It's much more comfortable than it looks and it can even fit 2 people inside! As it is deeper than a normal bathtub, you're fully immersed, even while sitting. It costed around 30€ (in Portugal).

To begin I cut the base of the bathtub out of 20mm thick plywood. The diameter of the base should be the same of the external top rim of the tank so the wood paneling will stand vertical.

To draw a circle I placed the tank upside down on the plywood and outlined it with a pencil.

After cutting the plywood base with a jigsaw I drilled a hole (a bit wider then the water outlet pipe) in the center of the base.

Next I applied two coats of marine varnish.

To prepare the bathtub base I started by drilling a hole in the center of the base of the plastic tank. The diameter of the hole should match the drain you choose. After, I installed the drain and added some sealant on the bottom part. Then I filled the tank with water to check if there was any leaking. (There wasn't :D)

Because my tank was somehow hollow I made some cement paste, turned the tank upside down and filled the concave bottom to make the base steadier. On top of the wet cement paste I placed the plywood base and let the cement dry. (Check the final notes to find out what my mistake was here).

To start applying the tongue and groove wood paneling I had to make sure the surface where I was going to apply it was even. My tank had two little handles that I removed with the angle grinder so the panelling would lay perfectly.

I measured the height from the bottom of the plywood base to the top of the tank rim and cut all the wood paneling to size.

I started by screwing the first wood panel to the plywood base and to the tank rim (don't screw anything to the tank walls, otherwise the water will leak!). Then, using paneling clips it was time to install the rest of the wood paneling. To do this you insert two clips in the groove of the first piece of wood, one at the base and one at the top and screw the clips to the plywood base and plastic rim, then fit the second piece of wood inserting the tongue inside the groove of the first piece (I used a hammer to carefully push the tongue inside). Repeat the process until the tank is fully covered. This was a surprisingly fast process.

To make the wooden rim I used some reused pine wood scraps 2cm thick and 8cm width, previously sanded.

I planed to make a circular rim but I ended up making a decagonal shape.

To find out the angle of each piece I used adobe illustrator. I drew two circles with the diameter of the edges of the tank rim and then drew two decagon shapes that would cover the circles. I decided to go with 8cm width so I could used the bathtub rim to place the soap or maybe a glass of wine. From this drawing I found out the angle which I had to cut the wood.

To cut the wood I used a table saw and made a simple jig to make it easier to cut all the pieces with the same angle.

To attach the wood to the tank rim I used stainless steel screws (I thought I would have to use bolts and nuts for this but screws ended up working fine) and then I covered the screws with wood dowels.

I made a paper jig to mark the center of the holes for the dowels. I marked each of the ten pieces of wood using the paper jig and a pencil. Then I drilled the wood with a 8cm drill only half the thickness of the wood.

I placed the wood rim on top of the tank in the right position and clamp all the pieces in place. Then I screwed the wood to the tank and used wood glue to cover the screws with the dowels. After the glue dried I cut the tip of the dowels and sanded all the sharp edges.

Finally I applied two coats of marine varnish and took the bathtub home. (Make sure to verify if it will fit trough your doors!!)

I placed the bathtub in place and connected the pipes together (in my case this was really easy because I can access the pipes from under the house, depending on your house structure this can be a bigger challenge)

Then I installed the faucet on a piece wood that I had cut with the same angle and dimensions of the rim pieces but 3cm thick. I drilled the holes for the water pipes and screwed everything from the back so it's not visible. My pipes are exposed so this was quite simple. Depending on where your water comes from you might have to do this in another way.

In the end I added a black circular curtain rod and some white curtains.

I really loved the outcome of this project and I've been using this bathtub to shower and bathe everyday for a year now without any problems. However, there are some things I would improve and others that I don't mind but you should have in mind when building this:

The main mistake I made was the hole in the center of the tank. Because from the inside of the tub the bottom is convex and the drain is in the center, this means the water doesn't completely drain because the sides are a bit lower and some water get's stuck there. If your tank is also not flat I would put the drain on the lower place of the tank (the sides in this case).

In retrospective maybe I should have spent some extra money to buy a black tank, this color is funny but I think black would be nicer.

The bathtub is quite high so think about that if you have low mobility or small children. Maybe adding a wooden step or choosing a lower tank could also work.

There is no overflow drain so you must be careful not over fill the tub.

This would also be a perfect outdoors bathtub (I'm planning to make one for the garden this summer :D).

I hope you like this project and I hope I was able to explain everything in detail, please feel free to drop me any questions you have and I'll try to help you out.

I never thought of building a bathtub before but I manage to do it in 3 or 4 days, alone, so you can do it as well!!