Introduction: Custom Bathtub Front Support Panel

This project is not likely something that many people will need to build, but you could easily make a sweet table top out of this, and it would be much easier.

We are remodeling our basement, and using plumbing that was installed when we bought the house. I did not want to break the concrete up to move the plumbing, and so I needed space to install my drain plumbing between the basement floor and the bottom of the tub. I decided to lift the tub up 6.5 inches to give myself room for plumbing. (In hindsight I would build it taller...probably 8 inches if I am honest). Our project was further complicated by purchasing a curved tub. It fit the space really well, but severely complicated this project.


Supplies Needed

  1. 3 sheets of birch solid core plywood
  2. waterproof wood glue (I used about 3/4 of a gallon)
  3. sandpaper
  4. table top pourable epoxy(1 gallon kit should do)
  5. Mixing supplies for epoxy (measuring cups, mixing cup, stirring sticks)
  6. Sanding Belts
  7. Construction adhesive

Tools required

  1. Kreg Jig Table saw ripping guide
  2. Bar clamps (way more than you think you need)
  3. Large Band saw
  4. 12" Large round power sander
  5. Kreg Jig Tool, Large one and screws)
  6. Large Router
  7. Large Roundover bit
  8. Belt sander
  9. Random orbit sander
  10. Level
  11. Caulk gun
  12. propane torch
  13. bevel gauge

Step 1: Cut Plywood Into Squares

In the picture above, you will see what the back of my car looks like with three sheets of plywood cut into 6.25" x 10" rectangles. I share a shop with a family member, which is great, other than the distance I have to drive to get to it. So I had to transport the material there before beginning the glue up.

I ripped the plywood into 6.25" inch wide strips with a kreg jig rip guide. You could do so on a table saw if you prefer. I then set a stop guide on my miter saw, and cross cut them to 10" long strips. It made for much faster cutting.

Step 2: Face Glue the Rectangles Into Rectangular Cubes

The whole point of this project was to see the end grain of the plywood projecting out from under the bathtub. To get started with this I faced glued pieces of plywood into about cubes that are about 10" wide, but the same dimensions as the plywood pieces were cut into.

In the picture you can see that I have lots of blocks clamped up for the glue to set. I tried to glue up three large blocks in one set of clamps so that I would have enough clamps.

I let the glue set for three days. I think that it only needed one or two days, but I just didn't get back to it the next day.

Step 3: Cut Rectangular Cubes Into Trapezoids

In this picture you can see the cardboard pattern that I made to make sure that I followed the curve of the tub.

Since it was a corner tub, I started with a square end, and then built around the curve as I went. I used a bevel gauge to mark out the angle that I needed to cut each block into so that it would fit on the curve. I wish that I had taken a picture, but I did not. I placed one end of the bevel gauge against the block that I had set down, and then moved it till it matched the diagram on my template. I then took that mark to the outside edge of my block, and used it to get a line that I could cut on the bandsaw.

Once the sides were cut with the band saw, I then used a 12" spinning disc sander to make the faces smooth, so that I would get a solid glue joint.

I ended up cutting 11 large blocks in order to make the curve. After they were all cut and sanded, I glued pairs of them together. I had no way to clamp up more than two of them, and so that was how it was decided.

The picture above shows the dry fit of all the blocks before I glued them up. You can also see a couple of the extra cubes that I made in case they were needed.

Another two day wait time...

Step 4: Connect the All of the Blocks Together.

When it came time to final glue everything together, I had no way to clamp it all together. I tried screwing blocks to the table, and clamping against them, but got unsatisfactory results.

Lacking a better plan, I used a Kreg Jig Extra large sized jig to screw the larger blocks together while the glue set. In the picture above you are looking at the top surface, as it has kreg jig holes on the back edge (where it would not be seen as it will be under the tub). The bottom surface has 2 lines of kreg jig holes on it, so that it would hold better while the glue was setting. Wait another two days to move that the glue would hold.

Step 5: Making a Fair Curve

So here is where this got really time consuming.

I needed to fair the "pointy" segments on the front of the curve, so that it looked like a smooth radius. I used a 4" belt sander and about 7 sanding belts to accomplish this. I held the sander on it its side, with the belt against the front face and just kept sanding till it had a smooth curve that I was looking for on the front face. I also used the belt sander to flatten out the top and the bottom of this project so it would sit more smoothly on the floor. This was the part that was very time consuming. If I were to do something like this again, I would actually make it about 3/4" taller than I wanted it in the final measurements, and pay a cabinet shop with a wide belt sander to bring it to my final dimension.

After it was flat, I sanded it as smoothly as I could with my random orbit sander, on the top and front faces. I did not bother on the bottom, nor on the back, as no one would see those faces after they were installed.

After final sanding, I used a large router, with a larger round over bit to make a simple round edge. I think that the plywood blocks would take whatever edge you wanted to rout into them, but I opted for a simple profile.

Step 6: Making It Water Proof, With Pourable Epoxy

This project is meant to be under the bathtub that my children will be using for the next 8-10 years. If you do not have kids, you need to know that your beautiful offspring will get water and mess everywhere, every time they bathe. That being the case, I decided that I wanted to make sure that I would not ever have any problems with moisture on this.

The first pictures taken after I poured the third or fourth coat of pourable epoxy. This was a neat portion of the project, and something that I have never done before. I opted to start on the top surface, so that any drips would show up on the bottom edge, and would not be visible upon installation.

A word on pourable epoxy...make sure you read up...lots and lots. The product that I got allowed me to recoat within 4 hours, as long as the surface was still slightly tacky. If you let it cure completely, you need to wait 24 hours and sand between coats. That being the case, I just planned on babysitting the epoxy pour for two days around my other chores that weekend. In between coats you need to use a propane torch to burn any bubbles out that appear. The first coat had lots of bubbles pop up, as the epoxy seeped into the end grain of the plywood. The next three coats got better in terms of bubbles, so that was nice. I also used plastic disposable trowels to knock down drips as they formed, that made the final sanding and cleaning up easier, at least I think it did. Also make sure that you either cover the floor where you are working, or work where you don't care about the floor. You will also want to keep bugs away from it, as they will inevitably land in it.

After the top surface had cured completely, I got help and turned it over so that I could take care of the bottom surface. I had to sand off the drips that I had missed, which required a steady hand to cut into the front surface.

You can notice the tape "dam" that I set up, to keep the epoxy off the front surface completely. It worked ok, but required some sanding again at the end of it. The bottom and back edge got three coats of epoxy to ensure its water proof coating. As I poured the back edge, I made another tape "dam" on the back side, with the idea being to send any drips our and over the tape, and off of the wood itself. It worked fairly well, but there was still clean up.

Step 7: Installation

After the final cleaning up, it was time to put on the floor where I wanted it, and glue it down.

I was nervous when it came time to do this. I set the tub on it two or three times to make sure that it would cover correctly, with an even reveal all the way around. When I new exactly where I wanted it, I marked the back side on the floor with a sharpie marker so that it would be in the exact same place.

I shimmed it level, marking the shims location on the floor with sharpie as well, so I would know exactly where they went.

After that, we picked it up, and smeared an unholy amount of PL 300 constructive adhesive underneath where it was to go, set the shims, and dropped it back down. I rechecked the level to make sure that all was good, and then had the kids walk on it to set the glue down.

Step 8: Final Notes

After the tub front was installed, I built a bathroom around it. The tub get set into place shortly after that, along with the tub surround. Then drywall, mud and paint, the usually stuff.

I would love to be able to tell you that this has been durable and have had no problems, but we have not completed our remodel yet, and so the tub has been unused other than my plumbing tests. I suspect that we will not have any trouble with it, I hope so, because I do not ever wish to take it apart, owing to the unholy amounts of constructive adhesive that is holding it down!

Thank you for your time, and have a fantastic day!

Plywood Challenge

Participated in the
Plywood Challenge