Can I Put a Hot Tub on my Deck?
Let's talk about something that we have been seeing alot of lately - inflatable hot tubs on decks. A quick Google search of “Can I put an inflatable hot tub on my deck” produces almost exclusively “Yes! Of course you can” answers. But when we actually begin reading them, these absolute “yes” answers turn into “well, maybe” answers. While these compact and lightweight options are a great entry level option to be able to enjoy the benefits of a hot tub, are they actually okay to be used on your deck? Let’s get into it!
Full Size Hot Tubs?
You may be asking “But why inflatable hot tubs? Why not full sized ones?” To keep things simple, we’ll just say that there are very rare occasions when a full sized hot tub should be placed on a deck, and none of them involve the average deck that is built at the same time as your house, or added after the fact. In the future, we’ll get into more detail regarding the best options for adding a full size hot tub to your space. Now, into the inflatables!
Most Common Inflatable Hot Tubs
To start, we have no affiliations with the companies or products mentioned, they were simply just the first results that popped up on Amazon. So, we have the Aleko Two Person Inflatable Hot Tub, the Intex 28429E Four Person Inflatable Hot Tub and the Intex 28451EP Six Person Inflatable Hot Tub. Now, the information shared here applies to all inflatable hot tubs, not just the ones mentioned, which is why we selected ones in varying sizes. So, with that out of the way let’s first talk about decks.
Deck Construction and Capacities
Deck loads are expressed in pounds per square foot (psf), which includes dead load and live load, and when adding the two together decks are generally designed for a 50 psf load. Dead load is the load created by the deck itself, and usually amounts to about 10 psf, but could vary and head more towards the 20 psf area depending on the decking material (composite vs. treated), the design, etc., but for our purpose today we will stick with 10 psf. Live load is the load created by use and would include any movable physical object including people, furniture, tables, grills, etc. and usually amounts to about 40 psf. So while your average deck is designed for 50 psf, live load is what matters here and we are actually looking at a number closer to 40 psf. Without going deep into the actual engineering of a deck and the size and spacing of framing members, beams, and footings, we’ll just utilize our 40 psf number.
Iowa Extras!
For those of us in Central Iowa, we reached out to a Johnston building official to see if they had any extra input that we missed, and they sure did! Here, we also have to consider snow load which amounts to 30psf. What this means is that with a deck designed to support 50 psf, we have to factor in our dead load of 10 psf and our snow load of 30 psf, which places us at 40 psf, with a deck designed for 50 psf.
You may be thinking “yeah, but it only snows 4 months out of the year MAYBE”.
You’re right, however when thinking about load capacities, you work with the highest common denominator, which would be 40 psf. What this means for you is that when you are deciding to place a hot tub (inflatable or full size) on your deck, you absolutely need engineered plans. The building official we spoke to said that they won’t even review plans involving a hot tub if they aren’t engineered.
A few other things that they mentioned (that we completely overlooked), is that IRC (International Residential Code) states that when a hot tub or pool is within 5’ of a window or door it has to be tempered glass, and this is especially true when a deck becomes involved. This means that you could have just installed all new beautiful windows in your home, and we’re going to rip a few back out! One more thing that was mentioned (and this is more aimed towards you full size unit folk) is that your electrical disconnect has to be viewable from the hot tub. For some people, this can be a major turnoff because they don’t want to have a box on the side of their house that they can’t hide.
In their opinion (and no, we had ours long before this call even though they are identical), there are few if any circumstances when a hot tub should be placed on a deck. Just some input from the officials that you will have to work with if you really want a unit on your deck!
Weight of Water
A quick clarification on how we figured our water weight so those of you following along at home are on the same page, water varies in weight slightly depending on the temperature of it, as follows
1 gallon of water at 39*F (4*C) = 8.345 pounds- 1 gallon of water at 70*F (21*C) = 8.33 pounds
- 1 gallon of water at 200*F (93*C) = 8.04 pounds
Generally speaking, hot tubs are kept around 100*F, so we figured our weights at a 1 gallon weight of 8.3 pounds (and because we’re deck builders and like easy math when possible)
Inflatable Hot Tub Sizes and Weights
Before we break it down, keep a mental note of which unit you think introduces the highest load, you may be surprised!
Starting with our Aleko Two Person Hot Tub, the dimensions are 77” long by 22” wide and 28” tall, weighing in at 52 pounds and a capacity of 145 gallons of water, this is our lightest option. When we figure our 1 gallon weight of 8.3 pounds, this unit holds a 1,203.5 pound capacity, and with the unit weight added in, has a final weight of 1,255.5 pounds before people are factored in. Being as the average person weighs 180 pounds and a two person capacity, we have another 360 pounds that is added to our total weight. With an overall footprint of 12 square feet (it’s actually 11.76 square feet for our mathematicians, but again, deck builders not professors), this places our total load at 134.6 pounds per square foot.
Next up is the Intex 28429E Four Person Hot Tub, coming in at 75” long, 47” wide and 26” deep, it has a unit weight of 101.8 pounds and has a capacity of 210 gallons. Multiplying by our 8.3, we come up with 1,743 pounds of capacity and a total weight of 1,844.8 pounds, an extra 600(ish) pounds over the two person option. But, because this is a 4 person option, we also have to consider the extra 360 pounds of people included over the two person option, adding an extra 720 pounds, placing our grand total at 2,564.8 pounds over a 24.5 (24.48) square foot area. This gives us a total load of 104.7 pounds per square foot.
Lastly, the Intex 28451EP Six Person Hot Tub, with a 94” length, 94” width, and 28” depth, this is our largest option by far. It offers a 290 gallon capacity and has a unit weight of 131.7 pounds, giving us a 2,407 pound capacity and a total weight of 2,538.7 pounds. With a 6 person capacity, we have to add in the 1,080 pounds of people, meaning we have a grand total of 3,618.7 pounds dispersed across a 61.4 (61.36) square foot area, giving us a total load of 58.94 pounds per square foot.
As you can see, the largest option weighs nearly three times as much as the smallest, however the total load placed upon the structural members of your deck is nearly half due to the total disbursement of the weight. Does this mean anything with a deck built per standard requirements? No, it just means the weight is technically more dispersed.
What Does All This Mean?
If you remember from earlier, most decks are built with a capacity of 50 pounds per square foot (psf), but after removing our dead load of 10 psf, we have about 40 psf to work with. What we are looking for here is whether or not our live load numbers are greater than 40 psf.
Our smallest two person hot tub came in at 134.6 psf, the four person at 104.7 psf and the 6 person at 58.94 psf. This means that generally speaking, none of these options can safely be placed on your typical deck. And just to add a quick note, you may see the downtrend in load as the size increases and think “so maybe a full size hot tub is the answer”. An average full size hot tub comes in around 102 psf, so definitely not safe.
We also have to remember that this is a very basic overview in which we are comparing the same factors straight across. Total weight comes into play, as well as joist size, joist spacing, footing size, soil capacity, beam size and placement, height of the deck, decking material, the location of the deck, any other loads present (roof, privacy fences, decorative metal privacy fencing, etc.). When considering all the above, it is easy to see why the majority (if not all) building authorities now require stamped engineered plans before allowing any hot tub to be placed on a deck.
I REALLY Want a Hot Tub, There Has to be Some Way
Of course there is! Putting them off the stairs of your deck in the yard, on patios, or near easy entry points to your home are great places, as long as they are level and secure. If you have a paver patio or something similar, it may not be the best place because these are generally built on a layer of sand, and the weight can cause shifting of the pavers.
If you don’t have a nice, level place, making your own concrete patio isn’t terribly difficult (we would give it a 6/10 on the DIY difficulty scale), just make sure to check with your local building authority for any regulations you may need to comply with, and spend a few days doing your research. If you think that this is out of your wheelhouse, call a local concrete contractor. For a simple patio a bit larger than your hot tub, most will likely be in and out in a day or less.
Again, also make sure that you are following any applicable code requirements as well.
I Don’t Have a Regulating Authority, Does That Mean I Can Put my Hot Tub on My Deck?
If everything we discussed prior hasn’t steered you away from putting an inflatable hot tub on your deck, then that choice is ultimately up to you. If you do choose to do so, we would HIGHLY recommend that you at least place a new supporting beam directly under where you plan to place your hot tub, professionally installed to meet standard building requirements for your geographic area.
And no, this doesn’t mean slapping a 4x4 held up by some 2x4’s under your deck and saying “That dude at Spectrum Remodeling said this makes it okay!”. This needs to be a properly installed structural support member to prevent future issues and ensure your own safety. Again, we do NOT advise you to do so, but if you decide to, at least stack the odds in your favor.
Conclusion
Inflatable hot tubs are a great option to give you the benefits of a full size option without the cost, but just because they are smaller and lighter still doesn’t mean that they are safe to use on your deck. Keep in mind that all the units we discussed are representative of all inflatable units out there, and that they can produce a load on your deck that are 2-3 times that of what it was designed to withstand. If you really want a hot tub on your deck, take the proper steps to get engineered plans and have them professionally built to ensure that you don’t put yourself or your hot tub pals at risk.
If you have questions about redesigning your space to incorporate a hot tub, questions about your deck, or really want to get that hot tub on your deck, reach out to us! We can guide you through the pros and cons of each option and come up with a plan that works for you. Or, if you decided that if you HAVE to deal with all these issues that a full size unit is the best choice for you, check out our other blog on how to incorporate a hot tub into your space!
