#DIY Building an Overflow #hottub - Waterproofing Stage

In this video series, we will follo wthe progress of Danny in the USA who is building an overflow hot tub into pool combination.

The remit for Danny’s build was that he wanted the water to be circulated through the spa, creating a waterfall overflow into his pool. He was going to use the pool heating and filtration system to do this but wanted me to design him a system that would allow him to have separate control of the hot tub jets.First things first, he needed a plan. This was a custom project (you can read more about these here) but with the right plan in place, Danny was heading in the right direction from the start.Enter the Pool BuilderThere are two parts to this build, the pool itself and the hot tub. What I have certainly found over the years is that pool builders don’t like to do hot tubs. Or, if they do, they often do them wrong!In Danny’s case, I will share a portion of an email that he sent to me. Basically, the pool builder only dealt in steel pools with liners so wanted to do the same for the hot tub – this was not going to work! You can’t get the jets you need for liners and they are a total pain to do where hot tubs are concerned – fine for a pool of course, just not a tub.Extract from Danny –Pool builders. When I suggested to my pool builder that he build something liek you did he was like “no way. I don’t do that. I only do steel walls with vinyl liners OR get drop the fiber glass ones in the hole and connect the suction line, return line and blower line. So I showed him a picture of steel wall hot tub (below) and asked him “So can you do this?” “Of course” he said. So then I said. “Well If I hire a mason or you hire a mason to build the concrete shell it is exactly the same thing. If the pool builder or the owner isn’t handy they also have to do the tile finish or find someone. But you get the idea. Now he’s like “ok let’s do it.” I think once a couple pool builders start doing it word will spread to owners or other pool builders. Yes I understand after a pool builder does it once they might not be a return customer but I think it will catch on and owners will be requesting their pool builders to contact you if the owners themselves can’t do it.As you can see, Danny was clear on what he wanted – and just needed to find the right people to do it.Let’s Get Digging!As with any pool or hot tub build, you have to clear the area so this is the initial picture from Danny of his build. Quite the project as you can see.It always surprises me just how much correspondence I actually have with my customers. In going back through my records to find the pictures and the videos that Danny has sent for this article, there was dozens and dozens of emails spanning over 12 months. Quite incredible really.Start with the PoolThe plan that Danny and his contractors had was to start with the pool. The pool was going to be a steel framed in ground pool with a liner. Quite straight forward to do but I do recommend getting someone in to do the liner part.Pool liners can be notoriously difficult to fit so should really be done by a pool professional or at least someone that has experience in them. I wouldn’t suggest trying to do a liner pool as a complete DIY project without assistance.And now the Hot TubWith the pool in place, it was time for Danny and the team to start work on the block built hot tub. He was going to make this from hollow CMU blocks with a rebar internal structure. This is a popular method for a DIYer.The first thing that he did was lay a concrete base. With the concrete base in place, it was time to start to lay the blocks.It didn’t take the brick layers too long to put the external and internal structure together for Danny.The next steps were to core the holes for the Gunite bodies to be fitted. It is pretty straight forward process but does take a bit of time. My recommendation here is that you hire a core drill, much easier and quicker than doing it yourself (like I did) with a regular hand drill.Danny then fitted the 2.5” pipes through the walls and then sealed around them. He also added a seal on the walls to add additional water proofing to the structure.External Pipe WorkWith the Gunite Bodies in place, it was time for Danny to fit the exterior pipe work. What he did which I think works well was that he actually fitted a sheet of insulation before he fitted the actual plumbing. Then it was time to put the 1.5” air lines and the 2” water lines around the tub to feed the 9 jets.With the plumbing in place, Danny then needed to fill in the seat void which he did with a mixture of concrete and block and then he has used a product called ‘Hydraflex” which is pink in nature to seal all of the concrete after it has been rendered internally. Again, this just adds another layer of waterproofing to the structure. It is certainly starting to take shape as you can see in the picture below.