A patio deck can be an idyllic place to relax and unwind, and a hot tub can be a luxurious addition. If you’re building a deck with a hot tub in mind or trying to figure out if your current deck can hold a hot tub, there are a few key factors to consider.
As a general rule, decks with a load-bearing capacity of 100 pounds per square foot (45.36 kg/sqm) can hold most hot tubs. Whether your hot tub can go on your deck depends on the weight capacity of the deck, as well as the size and specifications of the hot tub and a few other factors.
A hot tub either installed on top or built into the deck is a desirable feature for many homeowners, increasing the yard’s property value and relaxation factor. If you’re installing a hot tub, however, it’s important to ensure that the deck can support it for the safety of the property and inhabitants. Keep reading to learn more about how to make sure your deck is ready for your perfect hot tub.
Types of Hot Tub That Can Go on a Deck
You can install many kinds of hot tubs on your deck for ultimate relaxation, each with its advantages and shortcomings. Whether you’re building around a hot tub or installing one on top, it’s essential to know what kind of hot tub is best for your deck.
Size and weight are key factors that influence whether a hot tub is suitable for a deck. As a rule, hot tubs made of lighter materials are more likely to be a safe addition to your deck. If you know the load-bearing capacity of your deck, use that to decide the type and size of your hot tub.
Outside of its weight, it’s also important to take the features and requirements of the hot tub into account when choosing the right one for your deck. Hot tubs can range from inflatable tubs you can plug into a standard outlet to inlaid, jet service jacuzzis.
Inflatable Hot Tubs
Inflatable hot tubs are popular among some consumers because they can be stored away, allowing for a hot tub experience on a small deck that couldn’t support a hot tub permanently. They require only a standard grounded outlet for power and can bring the water to the ideal temperature in roughly an hour, depending on the size of the tub.
Sometimes referred to as portable spas, inflatable hot tubs are relatively light, averaging between 60 and 100 pounds (27 and 45 kg) when emptied of water. The lightweight body composition makes inflatable hot tubs a safer and more doable option for decks with a lower pounds per square foot load capacity.
The downside of inflatable hot tubs is that many consumers prefer the visual aesthetic of more permanent fixtures. Also, inflatable hot tubs are more prone to leaks and body damage than those constructed of more durable materials.
You must also take the additional hassle of emptying and refilling an inflatable hot tub into consideration if you have to mount the tub on an elevated patio deck.
Portable Unit Hot Tubs
Not all portable hot tubs are inflatable. According to Better Homes & Gardens, some hot tubs are designed to be movable as a single unit.
While not quite as on-demand as inflatable tubs, the advantage of portable hot tubs is their versatility and mobility.
Portable unit hot tubs must be seated on a level foundation and typically require some element of padding underneath. For these reasons, portable unit hot tubs are typically either installed on top of an existing deck or settled on the ground with the deck built around it. However, building the deck around the hot tub essentially eliminates the portability of the unit.
Portable hot tubs are typically more energy-efficient than permanent in-ground spas, making them more cost-efficient for the user. You can also take them with you if you move, which is another advantage over permanent fixture jacuzzis.
Portable Acrylic Hot Tubs
Acrylic hot tubs are typically manufactured in a standard design. Their popularity, however, means there’s a variety of industry-standard shapes and sizes, providing the freedom to choose the right tub for your deck.
Although acrylic hot tubs are generally more expensive than other materials, such as vinyl or polyethylene, they make up for the purchase cost with higher temperature retention, according to Hotspring. Acrylic hot tub shells keep more heat trapped inside the tub, which means they require less energy to maintain that sweet-spot temperature.
Portable Polyethylene Hot Tubs
Polyethylene hot tubs are typically a single piece of molded plastic. The space between the inner and outer shell of the polyethylene mold is filled with a specific powder. When the hot tub is in use, the powder melts into a liquid, ensuring that the heat is evenly distributed throughout the tub.
Polyethylene mold hot tubs are typically both cheaper and lighter than their acrylic counterparts. This makes molded plastic hot tubs a more popular option for deck-top installation. Polyethylene hot tubs generally weigh from 200 to 400 pounds (90 to 181 kg).
How To Tell if Your Deck Can Support a Hot Tub
Whether or not your deck can support a hot tub depends on the weight of the hot tub compared against the specifications of the deck’s structure. While this may seem like a simple math problem, comparing the weight of the tub to the load capacity of the deck, there are several variables beyond the dry tub’s weight that you must consider.
Consider the Factors That Contribute to the Tub’s Total Load
Here are some of the weight factors that contribute to the total load the hot tub imposes on the deck:
- Weight of the tub when emptied of water. This figure depends on the size, shape, type, and material of the hot tub. Most standard hot tubs weigh between 150 and 500 pounds (68 and 226 kg).
- Weight of the water. The approximate weight of water is 8.3 pounds (3.76 kg) per gallon. Multiply this number by the volume of the hot tub.
- Weight of maximum occupants. A deck must be able to support the hot tub when it’s full of both water and people. Most hot tubs will have a maximum weight and/or occupant limit in the manual. This must also be taken into account when considering if the deck can handle the hot tub.
Figure Out the Load Bearing Capacity of Your Deck
According to DecksGo, the first step to figuring out the maximum load capacity of your deck is to multiply the full area by 50 pounds per square foot (22 kg/sqm). Note that this doesn’t mean every deck has a load-bearing capacity of 50 psf (22 kg/sqm). Using this ratio, a 10 by 10-foot (3.04 m) deck would be designed to uphold as much as 5,000 pounds (2267 kg).
Beyond that bit of simple math, the calculations start to get difficult. The deck must be conceptualized in tributary segments, with each segment relating to the position of the joists extending from the house. The load capacity for each tributary area will vary due to differences in the size and structure of each zone.
The soil or foundation also plays a role in determining the load capacity of the deck. Because the entire weight of the deck’s load, plus that of the deck itself, is supported by joists and posts underneath, engineers must plan carefully to not overload the soil.
Why the Load-Bearing Capacity of the Deck Is Relevant to the Hot Tub
According to the Virginia Building and Code Officials Association (VBCOA), decks are surprisingly dangerous, with deck accidents making up a significant percentage of housing-structure-related injuries and fatalities.
Hot tubs are heavy units, which means an increased load on the deck. This, combined with the natural swelling that occurs when the wood is exposed to water and rapidly changing temperatures, means that decks with a hot tub are at a higher risk of damage or accident.
Keeping this in mind and ensuring that your deck is properly supported can help to reduce the risk of deadly accidents when you add a hot tub.
Consider Hiring an Engineer
The risk of both human and property damage associated with an improperly built deck justifies the expense of hiring a professional. If you’re unsure of your mathematics, experts from Fine HomeBuilding urge you to err on the side of safety either by consulting with a professional engineer or overbuilding the deck’s support structures.
Hot Tub Decks Should Be “Overbuilt”
According to Decks.com, a typical 8 by 8-foot (2.43 m) hot tub weighs over 5,000 pounds (2267 kg) when filled with water and bathers. A standard deck with a load capacity of 50 pounds per square foot (22 kg/sqm) isn’t strong enough to safely hold a hot tub of that size.
For this reason, it’s advisable to “overbuild” your deck if you plan on including a hot tub.
Overbuilding means adding more support structures to increase the load capacity. Because of the immense weight of water, it’s highly recommended that you build the foundation and support structures beyond the minimum code specs.
Lower Decks Have Higher Structural Stability
If you’re building a deck with plans to put a hot tub on it, keep in mind that lower is better. The higher up a deck stands, the longer beams are required to hold it up. Longer beams require more support structures and are more likely to have structural issues than shorter beams.
Powering Your Hot Tub
Hot tubs shouldn’t be located too near to any kind of electrical power source. The inevitable splashing that occurs as bathers enter and exit the tub can cause shorts or electrical fires if the hot tub is too near to exposed electrical lines or outlets.
If you’re having a large hot tub installed on your deck by an installation service, chances are they’ll set up the electrical work for you. However, if you’re working with a smaller hot tub, you may have to figure out the power source for yourself.
Most standard hot tubs require a 240-volt power source, which requires electrical installation. However, some hot tubs can operate using 120 volts. These lower-voltage hot tubs are called “plug-and-play hot tubs” and can be plugged into a standard household outlet.
Hot Tub Purchase and Installation Cost
If you’ve gone through all the steps, checked your math, and double-checked your support beams, now it’s time to make the purchase. Hot tubs range in price depending on size and quality. Larger and more luxurious hot tubs are naturally more expensive, both at purchase point and with installation fees.
The average price of a hot tub is $3,500, but it can range from as low as $500 to nearly $7,000. When trying to figure the cost of a hot tub, remember that some features, such as additional jets or underwater light fixtures, may carry an additional premium fee.
Installation prices for hot tubs can also vary, depending on many factors. The biggest pricing difference for installation is between in-ground and above-ground hot tubs. The cost of installing an in-ground hot tub can range from $1,000 to nearly $6,000. Compared to those prices, the installation fees for above-ground hot tubs tend to be much cheaper, averaging between $100 and $500.
Final Thoughts
Some factors go into deciding whether or not your deck can support a hot tub. An overloaded and under-supported deck can be dangerous, and the system for calculating an accurate load-bearing capacity is difficult. It’s highly recommended to allow a professional to design and build a deck if it’s intended to hold a hot tub.
As a rule of thumb, a deck with a load capacity of 100 pounds per square foot (45 kg/sqm) can handle almost any kind of hot tub. However, the safety standard for residential decks is only 50 pounds per square foot (22 kg/sqm).
