Hot Tub Installation: Step by Step

Rating: Pro
Once you made the decisions about what to install, the following list outlines the steps required.

1. Planning: Obtain all necessary local building permits prior to starting the job. As in other jobs requiring construction methods beyond the normal work of the water technician, I prefer to subcontract the work to others and let them do what they are trained to do, while I install the shell, plumbing, and equipment. In addition to hiring a general contractor to work on the construction and permit portions of the job, you might want to subcontract moving the electrical, gas, or water supply connections to the equipment area. You might also hire landscaping and masonry subcontractors.

2. Foundation: Working with your general contractor, carpenter, mason, or other subcontractors, plan the site preparation and coordinate the hot tub installation with any deck or other foundation work. Whether you will be preparing the deck and foundation or the subcontractor is doing it, a few concerns are often overlooked. First, be sure the deck is level. This might seem obvious, but if there is the slightest tilt, it will become very apparent when the hot tub is filled with water. A hot tub that is sitting on a deck that is not level will have a waterline that is high on one side and low on the other. This could be important if, for example, the high end is the side of the hot tub with the skimmer. To keep enough water in the skimmer to keep it from running dry, it might be necessary to fill the hot tub to the point of overflowing at the low end. Remember also that people in the hot tub will displace a great deal of water, so even if the variations are minor, they will become significant when the hot tub is in use.

Of course you might start out with level surfaces, but if the foundation for the hot tub and deck is not stable, the hot tub might not remain level. A hot tub that is full of water and three or four people will weigh over 2 tons (1800 kilograms). In a relatively small area, that weight creates a great deal of force for movement if it is not absolutely secure.

You will need to follow the building code in your area, but the objective is to secure the hot tub from shifting by supporting it in as many locations as possible, evenly set on the deck. It also shows how the hot tub rests in the excavation, surrounded by sand for general lateral support. The level is maintained by the deck.

Obviously, if the hot tub shifts the sand will compress and fail to support the hot tub. The advantage of that is that the sand also gives enough to prevent damage to the plumbing. Once the location of the hot tub is determined, a simple hole is dug in the ground, large enough to accommodate both the hot tub and the plumbing.

For this reason, I prefer an installation that supports the hot tub without filling the excavation with anything. As long as the base the hot tub is supported and the lip is secure on the decll there is no need to cover the plumbing with sand. Believe me, some point during the life of the hot tub you will need to access the plumbing, so preparation for that now will pay dividends later. Your subcontractors can help you install simple post and pier supports to create a framework to stabilize the hot tub, leaving the plumbing exposed. If the excavation is large enough and a deck access (or opening in a slope) is created, you will be able to easily diagnose and repair leaks. Be sure to use a solid concrete base in this type of installation.

You can also prevent leaks in this way. If the hot tub shifts for any reason, the pressure of the plumbing against the sand can crack joints and fittings. Erosion, earthquakes, and even frequent passing of heavy trucks can cause earth movement and shifting of the hot tub. My experience is that no matter how well installed it is, every hot tub leaks sooner or later. Site preparation makes the difference between a simple repair and tearing out the entire installation and starting over.

3. Bringing the hot tub to the Site: Acrylic and fiberglass gel coats scratch easily, so take care to cover the top of the hot tub to prevent tools, dirt, or sand from damaging the surface. You will need to work inside the hot tub, and painters' dropcloths make good working covers.

4. Plumbing: If the hot tub is preplumbed, skip ahead to step 7. If not, plumb the hot tub at the job site. Decide on the number and location of the jets, marking them with a pencil or felt-tip pen. Plan on installing a skimmer even if the hot tub is indoors in a clean area, because the skimmer will remove body oil or suntan lotion from the surface of the water. Locate the skimmer on the side of the hot tub closest to the equipment, but consider the seating pattern of the hot tub and avoid placing it where it will prevent someone from using a lounge or molded seat. Purchase the jet fittings, drains, and skimmer before you cut any holes in the shell.

5. Installing the Skimmer and Main Drain: Suction plumbing runs from a skimmer and main drain, joined with a T fitting or an optional three-port valve. Position the skimmer as discussed previously, then determine the appropriate height. The top of the skimmer opening will normally be only 2 or 3 inches (50 or 75 millimeters) below the lip of the hot tub so that the normal water level, in the middle of the skimmer opening, will be about 6 to 8 inches (15 to 20 centimeters) below the lip. Remember that bodies displace water, so if the skimmer is located too high and the water level is raised to fill the skimmer, when you add bathers the hot tub will overflow. In addition to the obvious problem of a wet deck and an unsatisfactory installation, the water loss means that when the bathers leave, the water level will drop below the skimmer opening and the pump will run dry. If the skimmer is located too low, the water level will be higher than the skimmer and the hot tub will have no skimming action. If you are in doubt about the positioning of the skimmer, take a look at a preplumbed hot tub or a unit already in service to get a feel for the best placement. The actual installation of the skimmer is simple. The skimmer is supplied with a faceplate and gasket that fit over the opening on the inside of the hot tub. Using the faceplate as a template, determine the exact position of the skimmer opening by holding the faceplate against the inside of the hot tub and tracing the opening with a pencil.

Mark the location of the screw holes. Remove the faceplate and drill out the screw hole locations to the size of the screws provided. I drill the screw holes before cutting out the skimmer opening because the hot tub wall is stronger before removing the material from the opening, and it is less likely to chip or crack than if I were to drill the holes after that portion was removed. Next, drill a starter hole within the perimeter of the skimmer opening to create an access for your saw blade. Use an electric reciprocating saw, jig saw, or manual keyhole saw (if you have a lot of patience) to cut out the skimmer opening. Hold the skimmer against the back of the hot tub, and apply the gasket and faceplate to the interior side of the hot tub. Screw them together with the hardware provided. Apply some silicone sealant to the bolts before slipping them through the holes. When you tighten the bolts, the sealant will fill any gaps.

Install the main drain, following the procedures described in step 6 for jet fittings. Some building codes require two main drains attached to the same suction line, joined by a T fitting or one drain with two suction ports. Since hot tub suction is extremely strong, should one drain be covered by a hand or foot, the other one will then pull water rather than a single one that might injure the bather. In this case, the second drain is usually mounted in the side while the primary drain is located in the floor of the hot tub.

Install any light fittings, following the instructions with each different model. Some will require creating a light niche in which the actual fixture is mounted. The niche is installed on the shell in the same manner as the skimmer. Others are designed more like a main drain, where the fixture is threaded to fit through a hole in the hot tub wall and screws into a body on the exterior like a jet fitting.

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