Thinking of all the other DIY projects we've done, this one is still my favorite! I should specify however that in this case when I say "we", I really only mean "Rob". I didn't do anything on this one other than take pictures and provide the beer. Which apparently is equally important.
He really went all out on this project. The math behind the build, calculating the pressure of the water against the planks, how many metal straps he would need to hold the barrel together and all the rest of the thought process and creativity that went into this is pretty epic I find.
First, materials used and how much it cost us to build it:
Western Red Cedar Wood: 750$
Used pump and heater from an old hot tub found on Kijiji: 150$
Piping: 200$
Metal bundle straps: Free
Total: 1,100$
Pretty cheap compared to traditional hot tubs right?!
This is the quick math behind the build:
5.5 ft diameter x 3.14 = 17.27 ft circumference
17.27 ft = 207.24 in, divide this by 5.5 (each plank is 5.5 in wide) = 38 planks needed
360 degrees divided by 38 planks = 9.47 degrees divided by 2 = 4.74 degrees which means each side of every plank was ripped at an angle of 4.74 degrees to form a complete circle.
Do your own research on everything first especially to figure out the water pressure against the straps, the best type of straps to use and how big to make the barrel. Based on Rob's research (we don't remember all the details because this was several years ago) this was the best size for metal bundle straps. It fits 4 people comfortably but 5 gets to be a little too cozy.
We then decided to dig it in the ground for a few reasons:
The piping doesn't show because it's underground
The ground helps it retain the heat
We wanted to walk into it rather then climb up in it (don't worry safety police, Rob also built a top so kids or animals don't fall in when we're not using it)
A few cons I would say though is if you're in a cold climate like we are, there is 0 insulation in this thing so if you were to start using it during the winter, your electricity bill would be through the roof. Maybe consider a different heating method, like wood burning?
The other con is that it requires a lot of maintenance. Having an old pump and heater can be unreliable and if you have to get to the piping underground well, good luck.
We winterize the pump and the pipes and we close it down for winter but we do use it like crazy from April to November when it starts to get chilly in the evenings. Especially the nights when it's a bit rainy (light rain), those are the best nights with the twinkle lights!
Either way, the "cool" factor of this tub definitely outweighs the cons as you can clearly tell...
(on hot summer days we just turn down the heat and use it as a cold tub)
I hope this was helpful! Just remember to do your own research first because we definitely did not know what we were doing and Rob just winged this until the end. There's definitely better ways.