Introduction: Make a Floating Deck for an Inflatable SPA, With a Motorized Cover.

About: Passionate of DIY of any kind, I am not of the trade (I am developer in computing) but I am self-taught and I like to learn new things. I decided to share my creations with you through photos and videos. I do…

The idea came at the start of quarantine: buy an inflatable SPA but do something nice around it and protect it (against cat claws for example!).

I therefore share my creation with you, an elevated 11 m² terrace, which includes an inflatable 4-seater SPA, 1.8 m in diameter. A hatch allows access to the SPA control (pump, heating, bubbles, etc.) A sliding cover covers it when not in use, it is motorized thanks to a gate motor, it can be controlled from a smartphone or by voice command with Alexa, just like the 4 spots along the wall.

Completion time: around 60H

Total cost: around 1200 € (Spa included)


Step 1: Plans

I drew up the plans which I adapted as the construction went on.

I had to adapt to sloping ground and, to limit the height of the terrace, I "buried" part of the SPA.

The woods used are class 4. That is to say that they can be in permanent contact with fresh water, these woods are more stabilized, they are rot-proof.

Step 2: Site Preparation

After choosing an unused location in the garden, I dug 20 cms the location of the SPA.

Then I installed 36 concrete slabs (from an old terrace) which will support the posts.

Step 3: Wooden Structure

I trace the joists following the plan and then drill the location of each post.

I used 8x80mm screws, the joist being 7 cms, I drilled it with a 15mm drill bit on half of its height.

The posts are cut with a miter saw, pre-drilled, then assembled to the joists, first with a power screwdriver, then by hand because my power screwdriver lacks power.

Once the end posts are installed, I continue with the intermediaries.
The posts are not all the same height, I take the sides as I go and I put them in place. In the middle, I put a double post to support both the terrace and the structure around the SPA.

The structure is made up of 5 rows of joists.

I then cut the struts to solidify the structure.
The goal is to be able to walk, without worries, even at the edge of the SPA.

Step 4: Mistake

Small but important mistake, I forgot to plan the location of the pump, and it cannot be moved away from the spa. So I modify the structure before continuing.

Step 5: Geotextile

I had forgotten to add it before, so with a friend, I lifted the structure to slide a geotextile underneath.

These are the same tarps that are used for flower beds, for example. This will prevent the growth of weeds.

Step 6: Deck Boards

I then continue with the installation of the blades which I cut with a miter saw.

They are screwed with special terrace screws (SPAX) and, using wedges, I leave a space between each for the expansion of the wood.

Step 7: A Big Hole!

I continue to lay the boards and when I reach the SPA level, I cut them roughly leaving them protruding.

I then trace the 185 cm diameter circle using a felt-tip pen and a string attached to the center of the circle. For that I fixed the provisional cleat which crosses the center.

I then cut off the excess pieces with a jigsaw.

Step 8: SPA Installation

At the moment, the SPA can be installed and put in water, I also take this opportunity to close the sides of the terrace.

I have also planned an access hatch in the upper part in the event of maintenance.

And of course I am the first to test the SPA !!

Step 9: Access Hatch

I cut out the access hatch for the heater / pump system, I reinforce the edges and I add hinges and a handle for easier access.

Step 10: Cutouts for Recessed Spotlights

I found some light points to bury, so I will have to adapt the pose.

I start by creating a 10mm medium jig, then I use my router with a copy ring to hollow out the outer circle. Finally, with a hole saw on a drill press, I drill the inner circle, which is smaller. I plan to drill the 4 small protruding studs and the spot fits perfectly.

Step 11: Installation of Spotlights

The spots are installed, I soldered the wires, added a heat shrink tubing and another tubing filled with special gel to seal the electrical connections.

Step 12: Cover

I move on to the creation of the lid: My first idea was to create a liftable lid with hinges. After calculations, the cover weighing about 100 kgs, it was not possible!

So I had the idea of a sliding cover using sliding gate elements (rails and wheels). So that I cover a high terrace board, I embed the wheels in the structure.

My equipment being limited, I start by "cutting" the outline of the cutout with a mini saw (Dremel DSM20), then I drill 3 holes with a 30mm bit and I finish with a wood chisel.

The base frame of the cover can then be assembled on the floor. I fix a temporary cleat, making sure that it is squared, then I fix the elements with the 8x80mm screws and I reinforce the angles with squares.

I cut the rails to the right size and screw them onto the terrace. For the connection between 2 rails I inserted a piece of threaded rod underneath so that the 2 parts remain firmly attached.

I install the cover frame and screw the 2m deck boards on it.

Step 13: Wall Decoration Panels

To hide this cinder block wall, I started by painting the upper part white, then I put blackout panels.

For the one on the left, since it was too wide, I cut it by taking it apart, removing the excess part, and reassembling it. The panels are screwed directly to the wall.

I also added the blades around the lid.

Step 14: Motorization

For the motorization, I recovered an old sliding gate motor and its rack.

At first I had attached the rack to the side of the beam but I did not have enough travel to open the cover fully. So I cut the fixing pastes and I fixed the rack under the beam to gain 14 cms of travel (ie 2 beam widths).

To save as much space as possible, I cut the geared motor unit as short as possible, and I created fixing pastes that I fix on threaded rods to be able to adjust it in height.

Step 15: Electronic

I made a control box which includes:

  • The 220V 24V power supply transformer and its rectifier.
  • A Shelly 2.5 module for remote control (smartphone and voice control with Alexa)
  • A Shelly 1 module for controlling the spots (idem)
  • A current measurement module connected to an Arduino Nano to detect an obstacle and stop the motor if the current increases (adjustable).

So, to open the cover I have the choice between manual control or asking the assistant: "Alexa, open the terrace".

I created protective casings for the engine and for the end of races. I also had to bring back a new sheathed electric cable to power all this (3x4mm²) and create a small electrical panel in the garden shed next to it.

Step 16: Access Hatch

I created an access hatch on the highest side to be able to access underneath if needed.

For this, I used offcuts from deck boards

Step 17: Live the Summer !

We have just spent a period of hot weather (yes, even in the north of France!) and we really appreciate relaxing in the SPA when coming home from work!

Step 18: Why ?

I have had several reviews on Youtube or Facebook since I posted this video, and here I will answer the points that come up often:

Why do all this for a simple inflatable SPA? Why not put a real jacuzzi?

A real solid jacuzzi costs at least 4,500 €, while this one costs 300 €, it's just a question of financial means!

Why not use an impact driver?

Simply because I didn't have one at the time. Now that I have been able to buy one, I will not know how to do without!

I leave it in the winter?
No, I empty it, I clean it and I put it in my garage.

How do I empty the SPA?

I use a small pool pump and send the water to a sump pit next to it.

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