Mel’s In Ground Hot tub Pavilion – Case Study

When Mel got in touch back in July of 2021, his goal was pretty straight forward. He had sent me a picture of a pavilion with an on ground hot tub that you can see below. This was the inspiration and this is what he was setting out to achieve. Oak framed pavilion with an in ground hot tub. Perfect.

My remit of course was going to be the hot tub and he had already taken care of the design of the pavilion.


There were a couple of challenges on the build for Mel. Firstly, the control room was going to be a good 40’ away from the hot tub. Secondly, he wanted to incorporate a “Kyle Lounger” – if you have followed the blog or the channel, you will have seen that I designed a contoured seat for Kyle’s build that has subsequently taken his name for any future builds.

The View

The difference for Mel was that he was not going to put jets in the lounger, but it was there as a comfy place to sit and look at the view of his lake. Yer, not a bad view at all. What a place to relax.

As Mel was going to be creating a contoured seat, he was going to form his hot tub. This is the process of creating a wooden mould, bracing it, then filling it with concrete. Quite a good way of doing things and an alternative method to block built tubs.

I should point out at this stage, Mel already had the pavilion in place. He had constructed that before the work began on his hot tub.

Forming the Hot Tub

As you can see from the images below, the initial forming of the hot tub went without a hitch.

You can see in the images above that the plumbing and the skimmer was already put in situ before the pour. This is normal when you are forming your hot tub build and exactly how you should be constructing things.

You can also see that Mel had run a cable for the light (and he opted for the too) and he was running this in conduit. If you are going to do this, one of the easiest ways to make sure you don’t loose water through this is by running the conduit up and over the water line. Then, even if it doesn’t seal properly for whatever reason, gravity is going to prevent water getting out of the tub. Kind of like a Hartford loop.

The Control Room

At the same time, Mel was working on his control room. As you can see from the image below, he is running a Heater, Blower, Spa Pack with external slave heater and also has a UV system in there for sanitation.

I’m sure Mel wont mind me sharing that it was with the control room where he had most of the problems. This is “normal” if I am honest as it is the area of the build where most people struggle.

Firstly, there was a problem with the UV System. In order to have the UV only working when the pump is running and water is passing through it, we were wiring it off the pump. It is low current draw so not a problem to do this. The idea was to wire it off the low speed but unfortunately, it was hooked up to the high speed. Not a problem, and a simple fix when Mel realised what was happening.

Configuring the Spa Pack was also a minor hurdle for Mel. When you get the Spa Pack, any brand, you need to make sure that they are configured correctly. This is something that I can help with and I have lots of documentation on it and videos too that can help – this is one of the areas where I can add huge amounts of value to your project.

With the control room build “under control” – see what I did there, it was time for Mel to turn his attention to the plastering of his tub.

Bring on the Tiles – well, sort of….

This is the next part that was a bit of an issue. The concrete build that had been put in place was too smooth, yes, you read that correctly, too smooth for his plasters to put the top coat finish on.

They spent two days chiselling and roughing up the surface before they could apply the finished coat. I am guessing they were worries about it lifting off if it was not adhering to the surface correctly.

The extra expense of 2 days labour Mel had no choice but to suck up.

With the build well and truly roughed up, it was time for the finished surface to be applied. The plasterers were now happy and confident that the finished surface was going to adhere to the concrete.

The last issue that Mel had was the priming of the pump. The pipes and the pump were below the water line but he was struggling to get the pump to prime. The best way of doing this is from the pump side, take the top off the filter and with a hose pipe, get as much water in as you can. Likewise, you can do the same from the union at the top of the pump. With enough water in, you should be able after a few “splutters” from the pump get it to prime itself which is what Mel did.

Fast Forward – wow, what a build

If you cast your eyes back to the top of the page and what the goal for Mel was, wow, he has well and truly smashed it out of the park. This is a beautifully constructed build in an idillic location and I am sure Mel and his wife “the Boss” will enjoy the tub and the views for many years to come.

Thanks for all your patience, guidance and support. As a project kind of guy this was a challenge but well worth the journey. Many of my mistakes could have been avoided had I read your documents more closely. But then again who buys a tool and reads all the instructions first. – Mel

What was my role?

My role in this build was as follows

  • Design of the tub
  • specification of the control room
  • supply of the parts
  • Supply of the custom hot tub cover
  • build consultancy assisting Mel throughout the process

Can I help you with your build?

If you are planning a DIY Hot Tub, Pool or Plunge Pool, then please do get in touch. Always happy to hear from you wherever you are in the World and whatever your hot tub or pool aspirations are, I am sure I can help.

Happy “well done Mel” Hot Tubbin’