Where to Put Your Hot Tub?
There are four major considerations on where to put a hot tub in a residential application. The first is finding an ideal location with adequate space. Hot tubs come in industry standard foot prints that can be as small as a 4’ x 7’ two person…. and as large as 8’ x 11’ 10 person…. Another measurement to consider when shopping for spas is height which can range between 30”-40” (36” is the most common). There are exceptions out there like swim/exercise spas which can range between 8’ x 12’ – 8’ x 20’, however, these serve a broader purpose for the user and go beyond just hot water therapy (we’ll address swim spas more in different section). Another factor for a hot tub shopper is shape. Over the years a multitude of shapes have been produced by manufacturers like corner shapes, octagonal, round, rectangular, oval, and even butterfly, however, square shaped hot tubs remain the most common. Ultimately, picking a shape and size has a lot to do with an individual shopper’s needs or limitations with one of these factors sometimes precluding the other.
Aside from size, other concerns when picking the location in your yard might be ease of access for bathers, privacy from neighbors, views, delivery access, and accessibility for a service/repair technician. One way to help you visualize the hot tub as you look around for the ideal spot is to take chalk, rope, or cardboard and create the desired size and shape you are looking for and place it in those locations to make sure they are adequate.
The second consideration is site preparation and foundation. Once you’ve chosen the designated resting place for your hot tub then the next decision is how to support the hot tub with a proper foundation. In the photo gallery section of this website you will find a great deal of visual imagery showing all kinds of customer applications.
When choosing any of the foundations below it is important to consider this formula for calculating pounds per square foot which can vary depending on the spa’s size and shape. This calculation is what you would present to a structural engineer or contractor that is preparing your foundation. This calculation becomes more important when a spa is elevated or raised such as a second story deck on a home or a rooftop deck.
Water = 8.33 lb/per gallon
Hot tub Gallons = most manufacturers specify this in their sales materials based on model
Hot Tub Dry Weight = most manufacturers specify this in their sales materials based on model
Hot tub Surface Area = take the length and width and multiply by each other to figure out the overall foot print
Calculation: 8.33 x Gallons + Dry Weight = “Answer” / Surface Area = Pounds Per Sq.Ft.
Example: Let’s take an 8’ x 8’ hot tub that is 450 gallons and weighs 800 lbs dry.
Calculation: 8.33 x 450 gallons + 800 lbs = 4549 lbs / 64 sq. ft. = 71 lbs per sq. ft.
The most common foundations are listed below. No matter which foundation you choose, it is important that it is made level before placing the spa so as to not void a manufacturer’s warranty.
Concrete Pad/Slab – A concrete pad or existing patio is the most common type of foundation prepared for a hot tub. Pouring the slab a minimum 4” thick and rebar reinforcing is recommended to prevent the slab from cracking over time. Also allowing proper cure time is important to prevent settling and sinking. Cure times for concrete can vary based on type of concrete used, time of the year (weather & temperature), and size/thickness of slab.
Crushed Gravel Bed – Crushed gravel or stone can also be a cost effective and fast way to create a hot tub foundation. The recommend thickness of the crushed gravel bed is 4 or more inches. It is also important to make sure this bed is compact so as to avoid settling after the spa is placed on the bed. Furthermore, using treated 4’ x 4’ timbers and screwing them together to build a square frame is a good way to keep the loose gravel in place when the hot tub is set.
Pavers or Blocks – These are another cost effective option when creating a foundation and can be very decorative and aesthetically pleasing as there are a multitude of shapes, sizes, and stone types to utilize. It is important to level out the area ahead of time with sand or crushed gravel before setting the pavers to avoid sinkholes or settling. The recommended paver thickness is at least 2 inches.
Prefabricated Hot tub Pad – Synthetic Spa Pads have gained increasing popularity over the last 10 years as a clean, quick, and easy way of creating a hot tub foundation. These spa pads typically come in small, interlocking squares and can be purchased individually to build whatever size foundation you need. They are made of a high density plastic so they are lightweight and very portable. They lack the permanency of concrete, however, have the advantage of being easily moved if you ever decide to relocate the hot tub within the yard or move it to another location.
Wood or Composite Decking – Decking is also a very common foundation for a hot tub since there is a great deal of flexibility with design to meet anyone’s taste and budget. As referenced above, it is important to consult a licensed contractor or structural engineer when placing a hot tub on an elevated deck due to the weight.
Another important consideration when doing a deck application is service/maintenance access. Most hot tubs and swim spas today are self contained units and have at least one service panel (many require access on all four sides for plumbing or additional equipment) that needs to be accessible to get to equipment (controls, pumps, heater, etc…). This can be difficult if one decides to sink the spa or lower it into a deck part way or flush with the surface of the deck to achieve a more custom or built-in look. This can be done properly by creating access hatches or trap doors in the decking surface all the way around the spa so that a service technician can easily remove that particular section of decking and climb down to access the equipment. The recommend size for an access hatch is 24-36” or large enough for a person to squeeze in-between the spa and deck.
In-groud Vault – Vaults are another great way to give your hot tub a custom look rather than an afterthought because they can be made to look like a natural part of the landscape. Lowering the hot tub into the ground also makes entering the hot tub very easy and eliminates the need for external stairs. The draw backs and concerns with sinking a spa in-ground are similar to that of a deck application because access is required on at least one side of the hot tub or more for servicing. When vaulting the hot tub it is important to build the vault 24-36” larger all the way around the hot tub so that a technician can climb down in the hole to access equipment. The gap between the hot tub and walls of the vault are typically filled with removable sections of decking or some other removable surface. Finally, it is important that a drain is installed on the floor of the vault so that rainwater or hot tub water can easily drain out and not pool.
Indoors – Putting a hot tub indoors makes for extremely easy bather access, however, it can be the most complicated from an installation standpoint. In addition to needing proper structural support for weight, access for service, it is important to have proper ventilation. Hot tubs generate a lot of steam and moisture which can cause mold, mildew, and potential damage to the walls of the home without proper cross ventilation. Exhaust fans and windows are a requirement for indoor hot tub installation. It is important to consult a contractor to make sure these pitfalls are properly addressed.
Finally, if the hot tub is being installed indoors, delivery access limitations such as doorways, stairs, ceilings and walls must be taken into consideration. Please have your delivery service review the site prior to delivery.
Gazebos – Gazebos are a very nice complement to anyone’s backyard and with the many shapes, sizes, and styles you are sure to find one you like. Gazebos provide privacy and shelter which attribute to increased bather usage over the course of the year. When preparing a foundation for a gazebo it is best pour a 4” or greater, reinforced, concrete slab. Since the gazebo has doors, windows, walls and roof like a home it is extremely important that the foundation be flat and level so that everything can be built true. Other important considerations for a gazebo are service access and proper clearance to get in and out of the hot tub. Again, 24-36” clearance around the hot tub is necessary in the event of a service call.
For more information on Gazebos please reference the “Gazebo Buyer’s Guide”
The third consideration is power & electrical requirements. Consult an electrician to ensure you have a large enough electrical panel to support adding a hot tub. Most hot tubs run on 220-240v electricity (similar to an oven or dryer) and typically require a 50-60AMP GFCI breaker, however, there are some models that run on 110-120v and require only a 15-20AMP breaker. In either case there must be a dedicated line and circuit which means the location for the hot tub can be dependent on how far it is from your home’s main electrical panel. In essence, the further the hot tub is away from the house the more wire, materials, and obstacles would be involved to do the job which can make the installation more expensive. For more detailed information we have a separate section on the subject of “Power & Electrical Requirements” . More importantly, there are national and state electrical codes and regulations as they relate to hot tubs so be sure to consult a local, licensed electrician.
The final consideration for a hot tub is permits and approvals. In most states, hot tubs are considered portable structures that are not permanently attached to the home, therefore, they don’t usually require a permit or approval from your city’s building and planning departments. Furthermore, they usually don’t require fencing if the hot tub has a locking cover that is ASTM certified or rated. If you live in a home, townhome, or condo that has an association and/or covenants then you may be required to seek approval first before installing a hot tub.