A hot tub is a beautiful and luxurious piece of decor in your home, a haven to relax and unwind when you need it. And once you have experienced just how soothing it can get, there is no going back! Landscaping magazines, resorts and the internet(duh!) are filled with stunning pictures of hot tubs housed on decks and the most mesmerizing and tranquil scenery you can imagine. I mean can you picture yourself soaking in the hot tub, with a chilled drink in hand(non-alcoholic of course) and gazing relaxedly at the splendid view all around. Probably you are wondering if you could get the same for your house too. I mean the view may not be as gorgeous, but it is still pretty great- it is home after all!
I will lay the good news at once – yes it is possible to put up your hot tub on a deck. Yay! Do not celebrate just yet. You have to consider a whole lot of things while you are thinking of doing this. On the onset, let me tell you that this is NOT a project you want to DIY on! Reserve that for the decors in your home. You need to hire the help of a certified professional to get this go-ahead and do the installation. And also, you need to be compliant with the city code, so there is that!
The last thing you want, after all that money you spent on hot tubs, inflatable or otherwise, is for your whole deck to buckle under the weight of a 1000 pound(minimum!) hot tub!
Decks you already have may not be able to support a hot tub. You did not build a deck with the intention of a hot tub, did you? Most decks are designed to hold people and some deck furniture – some chairs, a BBQ maybe. Definitely not a hot tub that can weigh from 1000 to 7000 pounds! There are some important considerations like structural support, weight and how the deck should be laid so that it can support a hot tub, the ideal location, electrical requirements and so much more! So, let us get at it without further ado!
Weight and support are 2 important factors. Weight of your tub with the water and the people in it and the structural support of your deck and what should be done to ensure it can hold all that weight above.
How much do hot tubs weigh?
There are two options for hot tubs on decks: one that sits above your deck and one that is built into your deck. The above-ground hot tub can easily be set over an already existing deck. However, you need to take the weight capacity of your deck and how much weight it can actually hold, into account.
Let us forget in-ground hot tubs for a moment. Hot tubs range from small to medium and can hold anywhere from 2 to 8 people in it. When empty:
- A small hot tub would weigh around 600 pound
- A medium-sized one would be around 750 pounds
- A large one approximately 800 pounds.
The weight of an inflatable hot tub when empty is not worth considering.
The weight of these hot tubs can vary from 2500 pounds for small tubs to 4000 pounds and more for large ones. Inflatable tubs weigh 2000 to 2750 pounds with water-filled depending on the size.
The bigger the size of the tub, the more is its filled water capacity and ergo more will be its weight. So a hot tub filled with water and teeming with people weighs quite a lot indeed!
How a deck can support a Hot Tub
A hot tub is a small piece of a unit. All of that weight we were talking about is concentrated in this fairly small area of your deck. Usually, in most houses, decks are raised 2 feet of the ground with support posts every 6 feet. This may not be enough to hold all that weight; it may just come collapsing down on the deck!
But wait, there is good news! If your deck is high off the ground, it is not all that difficult to add support beams and posts to support the weight of the hot tub above. Plus, if your deck is just above ground level, likely, it does not require any additional support. A deck just over the ground level can take 100 pounds per square foot of weight. This is definitely enough to hold most hot tubs in the small to medium range and inflatable hot tubs as well.
How much weight can my deck support?
You can do a rough estimate to determine how much weight your deck can handle. You have to find the weight of your hot tub per square foot. Let us get down to the math!
Firstly, calculate the load value. This will be the weight of the empty tub, its water capacity and the weight of the maximum number of people it can hold.
Load Value = Weight of empty tub + Weight of the tub filled with water + Weight of the people
1 gallon of water = 8.34 pounds
Let us consider a 4 person Tub. Say it is 40 sq. ft. with a capacity of 275 gallons and a dry weight of 750 pounds. Let us take 180 pounds to be the average weight of the people.
Load value = 750 + (275*8.34) + (4*180) = 3763.5
Divide this by 40.sq.ft and you get approximately 95 pounds / square feet or 95 lbs./sq. ft. This is the design load or the weight of the spa per square feet that deck must be able to support.
As we saw priorly, most hot decks can support 100 pounds per square foot. So this hot tub in the example we just saw should be able to be supportable by an average deck. In any case, never take any chances. Always contact a professional to get an estimate of how much weight your deck can handle.
The same thing holds for an inflatable hot tub. Even a large inflatable hot tub that can fit 6 people and has a 300 gallons capacity.
So, load value = (300 *8.34) + (6*180) = 3582
Divide by the number of sq. ft that gives 8532/40 = 90 pounds approx.
Here again, for decks just above ground level, there is no need for added support even for large inflatable hot tubs. For decks 2+ feet above the ground, even though inflatable hot tubs are not as heavy as standard, non-inflatable ones, we still recommend getting professionals to come over to check if it needs some added support. Or, if you plan on getting a full-sized, regular hot tub later on. Just keep your options open!
How can I reinforce my deck to add a hot tub?
Now that you know all about the weight and support factors to be taken into account, you should also know that decks that are 2 feet or higher will need added support.
- The supporting posts should not be placed more than 30” apart. Moreover, they should be placed in poured concrete. And they ideally run a foot below the frosting run, minimum.
- When you are modifying an already existing standard deck at your home to fit a hot tub over it, ensure that the footings, joists and the decking itself are all perfectly sound without any rot or damage evident.
- Have a certified contractor come over to your place and check with the city permits for support and details of permits.
- Placinging additional support beams
- Adding joists: Get a carpenter to add extra joists to the ones already in place. You need to make sure that they are in the exact spot where you are going to put the hot tub.
- Install ledger board fasteners: depending on the weight of the hot tub that will go over the deck, you can install up to 4 ledger fasteners.
- Using high-quality steel nails: when the modified blocks are nailed into the decking, using high-quality steel nails will provide maximum strength.
Now that the tough part is over, let us see how you can place your hot tub on your deck and the other important factors to consider.
Placing your Hot Tub on your deck
Where and how you place your hot tub on your deck will be the next big decisions you are going to have to make. Follow the steps below for a hassle-free experience.
Distance from the house: You are enjoying a nice dip in your hot tub suddenly it gets a little too chilly. Or, it starts to pour, so you need to dash in quickly. If you place your hot tub against the wall of your house, you can dash in quickly and get all warmed up.
Protection from chilly winds: Take a note of how windy your place is. Corner locations are more preferable.
Slip-resistant mats: Place slip-resistant matting or decking leading from the hot tub to your house. Also, ensure that the path from the hot tub to your home is well lit and has slip-resistant mats so that you can easily find your way back home without any mishap.
Space around the hot tub: Accommodate adequate space around the hot tub to use the covers and for you to conveniently get in and out of the spa.
Scenery: Position your hot tub in such a way that you can enjoy the backyard scenery during your spa sessions, but this should not obstruct your view when you are inside the house looking out.
Privacy: No one wants to relax in a hot tub when their neighbors can peek in on them! Consider adding a privacy fence, a pergola or foliage to give yourself some privacy to enjoy.
Power Source proximity: Your hot tub should be close enough to a power outlet to plug it in. There should also be sufficient ventilation and space for drainage. Leave enough room surrounding the tub for splash out during a hot tub session.
If your tub is going to sit over a concrete slab, the electrical wiring must be run in conduit and placed before the concrete is poured.
A GFCI(Ground-Fault Circuit Interrupter) is a must-have for your safety and protection. Smaller spas can be plugged into a 110v/20-amp outlet whereas a larger unit requires a 220v/50-amp connection.
Space: You should take a note of how much area the hot tub will take up as well as the surrounding space for easy getting in and out. A clearance area of 2 feet around the tub is ideal. If you can make more room, then great!
Small inflatable hot tubs are around 70-inches in diameter. Adding the 2 feet clearance space, you will need a 10 feet space to fit your tub comfortably.
The material of the deck: You can have either a wooden deck or a composite deck. The latte does not stain, crack or splinter.
The gap between the deck boards: As far as space between the deck and the hot tub is concerned, the gap should be small enough that your toe cannot enter but large enough for the water to drain and the wood to expand and contract. This will ensure your safety and lumber longevity.
I hope this extensive and mammoth guide answered every question you had in mind about whether your deck can support your hot tub. We explored if it’s a good idea or not and saw how much weight a deck could support. With all that water and all the people in it, a hot tub can get pretty heavy, so your deck should be able to support this mammoth weight.
Even for bigger inflatable hot tubs, it’s recommended to get a professional opinion if your current deck can support its weight. Follow the tips on reinforcing your deck for a hot tub and then have your tub placed over the deck with professional guidance. There’s a lot of work ahead of you, so get started!