I'm a DIY kind of guy, I like making things and would often rather make something than buy it.
This hot tub project may not be elegant but just about anyone can make one.
Step 1: My DIY Hot Tub
I got this idea recently when moving house. The previous tenants left these 2 old sofas. At first I was annoyed thinking I was going to have to get rid of them but as I sat and pondered them I got this idea for a homemade jacuzzi. Sure it's not the fanciest thing around, but it works and it's comfy too.
Built-in commercial hot tubs can cost upwards of $5000. Take a look at this DIY Hot Tub made from 2 old sofas, some reinforcing and a rubber garden pond sheet. Not many tools are required and it can be built for around $250.
Step 2: Find Your Sofas
The main structural support for this hot tub are the 2 sofas which will also provide the seating. It's up to you where you get these from but I suggest places like the nearest flea market or charity shop. Even a landfill site may have just what you need.
These sofas will be the major expense. Water weighs a lot so your sofas will need to be strong to support all that water. Sofas that stand on legs or struts are to be avoided. Ideally you want a sofa that sits flat on the floor with a high back and one that still has a good plump amount of cushion. The 2 sofas should be roughly the same size so that when they are put together they make a square.
You need to think about where you are going to build your hot tub.. Is should have easy access to drainage and to water. Select a location and clean it thoroughly by sweeping away any sharp rocks, twigs or anything that may tear or damage the liner.
Placing a square of old cheap carpet or a ground sheet can also help keep the liner intact.
Once you have prepared the location place the two sofas together with just enough space between them to allow for the legs of everyone on both sofas. Making this space wide enough to sit in will make it comfortable for taller guests.
Once your sofas are in place take some MFC board and make a box around the sofas. Waterproof wood is not necessary as the boards will be covered by the rubber liner. Attaching the boards can be done in many ways.
Use glue, screws or nails. It does not have to be too strong as the load bearing straps will hold the weight of all that water.
Once the boards are attached place the straps around the structure and tighten till there is no play left.
Get good quality straps as they are going to hold quite a lot of weight. Depending on how big your sofas are your hot tub could hold between 1000 and 3000 litres of water. Use at least 10 straps rated to hold around 300kg's
I always like grabbing a can of foam filler and what better way to fill all the gaps in your DIY hot tub.. Just think about where pressure is likely to be exerted on the rubber sheet. Some areas to look at are at the bottom of many sofas where there is a gap and around the armrests where they meet the boards.
Use polyurethane foam and apply liberally to provide as much support as possible for the liner.
The Rubber Liner
The easiest step of all is positioning the rubber liner. As a minimum use rubber garden pond sheeting that is at least 0.5mm thick. There is thicker sheeting available but from my personal experience 0.5mm sheeting works fine. Mine has survived a lot of punishments with scrubbers, cleaning agents and broken glass.
The rule of thumb for calculating how much sheeting to buy is simple. Calculate the surface area of your hot tub and then multiply by 4. Remember you need enough to cover the outside as well. The wooden boards need weather protection.
When putting the rubber liner in I prefer the messy fashion. Rather then carefully positioning the liner just place it loosely in place. It's better to err on the side of caution and be generous when laying out the sheeting. When the hot tub is full the weight of the water will compress the sofa cushions which will stretch the rubber liner. If there is not enough material the liner may rupture. If you place too much liner in certain places it will just form a harmless little flap which you can easily remove next time the tub is emptied.
That's about it for the construction phase. Time to think about water and hygiene.
Water & Keeping Things Warm
Although there are a number of options for getting hot water to your hot tub. The easiest solution is to fill it with hot water direct from your tap. When the temperature starts to drop just add a little more hot water.
You could use a more complicated and more expensive heating method like copper pipe through a fire or buying and electric water heater and pump. This all could cost as much as the whole project. For me keeping things simple works best.
My method may costs a little more than reheating and sanitizing the water over time but it's easy and any added expense is spread over time.
Clean Water Method
Clean and hygienic water is essential in your hot tub.. Your friends aren't likely to come back if they have experienced a rash or skin irritation. Because my DIY method does not include any pumping or water filtration I simply empty the spa water after every use and then clean and scrub the liner.
If you have hard water or a water pH level that is too high or low the use of certain water conditioners and treatments might be advisable. You really want that spa water to feel as soft and clean as you can. Chlorine tablets can also by used but make sure your get the dosage correct.
Thats it! This DIY hot tub was a fun project. I didn't really know how long it would last and was quite sure it would break the first time I used it.
Well three years later and I have just replaced my trusty DIY tub.
I've had some much fun and good times in my hot tub that I decided to upgrade to an inflatable hot tub. One with real bubbles and a filter..
For those who might be interested check out this place, it will find the cheapest Inflatable Hot Tubs