Is this wooden box for hot tub right?

Hi everyone im new here.

A few weeks back I saw few videos of diy hot tub and got interested in building one.

I have this old plywood box that has sunmica layered inside.
I was wondering if this can be used to build a hot bathtub.

I am planning of using a copper coil on a stove to get the water heated.

I have applied some sealing clay on the inside in corners and used this waterproof tarp to make it leakage proof..

Is this sort of box suitable for hot tub
How much copper coil is needed to heat around 95 gallon water

Please suggest
Thanks 🙏

Andrew Minalto wrote:Hi everyone im new here.

A few weeks back I saw few videos of diy hot tub and got interested in building one.

I have this old plywood box that has sunmica layered inside.
I was wondering if this can be used to build a hot bathtub.

I am planning of using a copper coil on a stove to get the water heated.

I have applied some sealing clay on the inside in corners and used this waterproof tarp to make it leakage proof..

Is this sort of box suitable for hot tub
How much copper coil is needed to heat around 95 gallon water

Please suggest
Thanks 🙏

Sorry I can't answer your questions. I hope someone with more hot tub experience can chime in.

I would worry about humidity with those panels. They look like plywood? They might de-laminate over time.

Most of the public baths here are stone masonry. I have been in a cedar tub before I think, but I wasn't really paying attention to the construction at the time.

Good luck with the build!

L. Johnson wrote:

Andrew Minalto wrote:Hi everyone im new here.

A few weeks back I saw few videos of diy hot tub and got interested in building one.

I have this old plywood box that has sunmica layered inside.
I was wondering if this can be used to build a hot bathtub.

I am planning of using a copper coil on a stove to get the water heated.

I have applied some sealing clay on the inside in corners and used this waterproof tarp to make it leakage proof..

Is this sort of box suitable for hot tub
How much copper coil is needed to heat around 95 gallon water

Please suggest
Thanks 🙏

Sorry I can't answer your questions. I hope someone with more hot tub experience can chime in.

I would worry about humidity with those panels. They look like plywood? They might de-laminate over time.

Most of the public baths here are stone masonry. I have been in a cedar tub before I think, but I wasn't really paying attention to the construction at the time.

Good luck with the build!

Thanks!! You are right about plywood and humidity.
I might use something else inside to make it waterproof.

Hope other members can also provide there advice on this topic.

Part 1:
Did you build this box?
Do you have any idea what type of plywood it is?
Do you have any scraps of the plywood left?
Why these questions - Some plywoods are water safe and some de-laminate at the drop of a hat when exposed to moisture. Personally, I wouldn't want to put a lot of time into this project without knowing which breed you've got.

Part 2:
What are the dimensions of the box?
Why - You mention 95 gallons, but have you allowed for the displacement of water for your body?

I remember once seeing a wooden bath tub, but the walls were a lot thicker and it was solid wood glued with water-proof glue. It was a similar shape to your picture - relatively deep, but small so one could soak up to the shoulders in comfort. That said, something with curved corners would be easier to clean. Think cedar-strip canoe type building system. Modern cedar-strips mostly use epoxy resin which is rather yucky, but if properly cared for, at least they last a very long time. I'd be researching natural waterproofing systems if I went that route.

I admit I'd love a hot tub! I worry a bit about the temperature issue - getting the water hot enough that Legionnaire's Disease and it's relatives aren't a problem, and then cooling it. Heating water takes a lot of energy.