Building a Hot Tub: Navigating the Unknown (Brandon’s DIY Wooden Tub)

Last updated: September 2026

This article was written by a customer of mine, Brandon Casci, and first appeared on his blog at brandoncasci.com. It’s an honest account of building a hot tub when you don’t know what you don’t know, and I love it for that. Over to Brandon.

Why build one?

I went to Iceland a while back, which was fantastic. During my time there, I enjoyed a daily soak in a hot tub. So I thought, damn, I need to get one of these for my house some day. I would shop around, but never pull the trigger. Finally, in 2019, I made the decision to pursue this.

I wanted a big round, 4 feet deep cedar hot tub. Since this was a pretty expensive purchase, and I didn’t want to be compulsive, I figured I would budget for it. January 2020 rolled around and I was ready to buy, but I was caught up on which cedar tub manufacturer to buy from, and I had it down to three. Then February 2020 came, the COVID-19 shutdown, and everyone bought every hot tub, all at once. There was an 18–24 month wait, but I wanted a hot tub sooner than that.

That’s when the idea of building one struck me. How hard could it be? So I got to work around October 2020.

The design

I originally intended to base the hot tub on a prefabricated water tank, but due to supply chain issues, I could not get a tank in the right dimensions, so I went with a custom-built wood basin with a custom liner. The hot tub forums had a lot of misinformation about what you can and can’t build a basin out of, so I looked into aquafarming and backyard fish enthusiast communities, and picked one of their designs.

I bought the hot tub parts, which are the controller, heater, filter and other related items, from buildahottub.com. Andi over there knows everything about these systems.

The basic specs are:

• Above-ground design
• A base framed with pressure-treated timbers and filled in with 0.75 inch packed stone
• Walls built with standard construction boards, filled with insulation, and lined with plywood and siding
• An industrial pond liner, custom made in a box shape
• All the necessary hot tub heaters and controllers
• Plumbing pipe, hoses and connectors
• A standard hot tub cover

Problem 1: city permitting

The first wrinkle was the city permitting. I started this process in September 2020. We are allowed to have hot tubs, but I needed an electrical service upgrade on the house to accommodate one. It took the city about 6 months to sign off, which threw some dependencies off course. I only interacted with them a little. I didn’t get the sense they excelled at customer service, and I’m totally fine not having to work with them again. I later learned, after speaking to local tradespeople, that a significant number of electricians will not take work in my city.

Problem 2: changing the construction location

By now it was October. I originally planned to build the hot tub where it was going to be used, but since the city was doing what they do best and the weather was turning, I opted to begin work on the basin indoors. This meant building the basin so that it could be taken apart and reassembled in its final location.

Electrical work approved

It was now March 2021, and the city finally agreed the electrical work could start. The delay was over the location of the electric meters. Meters usually go outside the house, but ours are inside, for good reason: we live in a dense area, and there’s nowhere else for them. The city insisted they be moved outside, but every alternative spot had a problem, from the sidewalk to the narrow driveway. It took several meetings, and input from both the electrician and the utility company, for reality to set in, which means the meters are staying where they are.

Problem 3: a less than ideal basin liner

I chose an industrial pond liner because at the time, it was the only one I could find that could be custom made into a box shape. Had I known a bit more about what to look for, I could have had a box-shaped pool liner made. Both types of liner are durable and will hold water, but the pond liner isn’t compatible with the seals on the through-wall fittings. The through-wall fittings are the plumbing parts that circulate the water between the basin, filter and heater.

So after a lot of leaks, I had to come up with my own through-wall design for this type of tub. On top of that, I also had to remove the hot tub jets and replace them with a jet-like construct that I made out of standard plumbing parts, so I could get those to seal correctly.

Problem 4: unexpected mistakes

I don’t think many people have built a hot tub like this, and since this was my first try, I made mistakes. One of them was making some cuts in the liner. To repair them, I had to learn how to heat-weld.

Conclusion

Today, I have a fully functioning hot tub that holds water, along with some plumbing skills that I’ve had to use a few times since then.

My take on Brandon’s build

Thanks, Brandon, for letting me share this. What I like about his story is that it’s honest about the bits nobody warns you about: the permits, the weather, and parts that don’t quite work together.

A few pointers if you’re planning something similar:

• Liners and fittings. Brandon’s biggest headache was getting standard through-wall fittings and jets to seal against a pond liner. It’s the main reason I steer people away from liners on hot tubs. See Can I use a liner on my DIY hot tub?
• Start the paperwork early. Brandon’s permit and electrical service upgrade took around 6 months. Check what your city needs before you buy anything. See Do I need a permit for my hot tub? and A guide to hot tub electrics.
• Above-ground and wooden options. If you like the idea of an above-ground or wooden tub, have a look at Above ground hot tubs: how to build your own, How to build the ultimate DIY wooden hot tub and How to build the ultimate DIY stock tank hot tub.
• Insulate it. Brandon’s insulated walls are a good call. See DIY hot tub insulation.

Planning your own build?

If you already have a cedar or wooden tub, my complete cedar/wood hot tub plumbing kit gives you the pump, heater, filter, controls and fittings in one box. Just add the tub and pipe. If you’d rather build a tub that won’t need a liner at all, my DIY hot tub plans give you CAD drawings, the plumbing layout, a parts list and the video course.

FAQs

Can I use a pond liner in a DIY hot tub?

It will hold water, but as Brandon found, a pond liner may not seal with standard through-wall fittings and jets. He had to design his own fittings. I’d avoid liners on hot tubs where you can.

Do I need a permit to build a hot tub?

Often, yes, especially in the USA, and particularly for the electrical work. Check with your city or county before you start.

Can I build a hot tub indoors and move it outside?

Brandon did, by building the basin so it could be taken apart and reassembled in its final location. Plan for that from the start.

Have you built something unusual? Tell me about it in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi