Having a sturdy level base for your hot tub is vital to ensure your hot tub functions correctly and does not get damaged. Many dealerships will recommend tradespeople to build the foundations for you, and if you are not confident in DIY, then this is a good option for you. However, building a base for your hot tub is straight forward, and by doing this yourself, you can both save money and construct the base that suits your yard best.
In this article, we look at all the different hot tub bases with details on how you can build them yourself. I will also include some handy tips that will save you money and time! If you are looking to build a base for your inflatable hot tub, you do not need such a sturdy base, but will have to think about heat insulation; I have explored this at the end, so you can scroll down and skip the bulk of this article.
What is the weight of a hot tub?
In the specification of your hot tub, the manufacturer willdetail the weight of the hot tub when it is filled with water. This weight willvary between 3200lbs and 4500lbs depending on the hot tub design. (For example,the Cotswold hot tub I reviewed weighs 3370lbs when full.)
After you know the weight of your hot tub when full of water,you need to add the maximum number of people that may be in the hot tub. For astandard 5-6 seat hot tub, the worst case scenario is seven people. The averageperson weighs 185lb, so the maximum added weight is 185 x 7 = 1295lbs
Is a hot tub heavy…?
A total of between 4495lbs and 5795lbs may seem like a lot(and it is if you were trying to lift it!) but spread out over 49 square footof a hot tub; the weight is only around 100lbs per square foot! In engineeringterms, this is light, so when we build our base, we need to concentrate ongetting it level rather than making it super-strong!!
Deciding where to build the hot tub base
Choosing where to construct your hot tub base needs someserious consideration. You will need to be able to access the hot tub all yearround so it will need to be near to your home. You will also need room aroundthe hot tub to service it, and you will need space to open and shut the lid.
The area needs reasonable drainage so that you are notstepping in muddy puddles before entering the hot tub. Also, as you and yourfamily exit the hot tub, you will be surprised by how much water drips off youand this will need to soak away as well.
The best position for your hot tub
The perfect hot tub position will not be overlooked by the neighbours and will be landscaped into the garden using screens and potted plants. It will look like a little oasis and will complement its surroundings.
Beware of overhanging shrubs or trees that will drop leaves, flowers, or pollen into your hot tub. Extra contaminates mean that your filtration system will need more maintenance.
Finally, your electricity and water supply will need to beclose to the hot tub. This tip is obvious, but I needed to mention it anyway!!
Concrete hot tub base
Concrete has been used to build hot tub bases for years, andas a building material, it is very versatile. It is easy to make level and willout-live your hot tub if built correctly. The disadvantage is it can beexpensive, and it is not very environmentally friendly as some of the otheroptions detailed in this article.
Building the frame for the concrete
First, you will need to make a timber frame to set yourconcrete mix in. The size of the base will need to be larger than the hot tub.I recommend at least a foot longer in each direction.
You will then need to remove any turf and topsoil. I woulddig down the same thickness as you are going to make the base – five incheswill be sufficient. Having the top of your base level with the surrounding soilmakes it easier to position the steps where you need them.
If your base is under 10 foot in each direction, you willnot need expansion joints so you can mix and pour all in one go.
What ratio of cement to aggregate should you use for the hot tub base?
As we said before, you do not need to make the concrete mixtoo strong, so mix to a ratio of 6 buckets of ‘all-in aggregate’ to one bucketof cement; a 1:6 ratio is perfect. Ihave heard people suggest that you need a ration of 1:3. This ratio is the samestrength used in foundations to build houses! We are not building a house, justa level piece of ground to put our hot tub on!
All-in aggregate
Using all-in aggregate will also save you time as the sandis already mixed in, and the ratios will be excellent for what we are building.
To calculate how much all-in aggregate you will need to use,multiply the length by the width, by the depth and then divide by 27 to get thecubic yard or multiply by 0.0283 to get cubic meters. Then add an extra 10% tobe sure you have enough
I find the math too complicated, so I use one of the manywebsites that will do the calculation for you. I have linked one below, but ifyou google concrete calculator you get pages of suggestions!
https://www.calculator.net/concrete-calculator.html
Top Tip: Buy a cement mixer on eBay!
Mixing this much concrete by hand is too much hard work. Buya cheap mixer on e-bay and then sell it afterwards. Look out for auctions thatare ending on random days or when events like the Super Bowl are on. There willbe fewer people bidding, and you may get a bargain. When you go to sell themixer, make sure the auction ends on a Sunday evening when there is likely tobe more people bidding.
Gravel hot tub base
Building a gravel base is the easiest option, but some sayit is not cosmetically pleasing! I think they look fine and if you do not likethe color of the gravel that is exposed, then you can buy ornate gravel tocover it. The main advantages are gravel bases provide excellent drainage, andthey are cheap to install. Out of all our options, this is also the mostenvironmentally friendly solution.
Unlike the concrete base, the wooden supporting structurewill have to remain, so it is vital that this is made from pressure treatedwood, and that any cut ends are treated with a wood preserver. Depending onwhere you live in the world, this frame will last between 2- 4 years. Theproblem is the underside of the wood is in contact with microbes in the soil,and they will eventually eat the wood.
Building a gravel hot tub base
The process is initially the same as making a concrete slab.You will need to remove any turf and topsoil and build a timber frame. Usepressure treated wood and secure with 10/12 inch galvanised lag screws; thetype used to construct decking. 12inch nails will also work but will make thejob harder, in my opinion.
Before you lay the gravel, put down a water permeablelandscaping cloth. This cloth will stop any weeds growing up through the gravel.Use a medium/course gravel (crushed rock), making sure it is packed in tight.You can finish with pea gravel to get the base perfectly level. However, if youhave domestic cats that visit your garden, do not leave the pea gravel exposedor they will use it as their litter tray, which detracts slightly from the hottub experience!!
Prefabricated hot tub bases
There are a number of prefabricated hot tub bases on themarket, and they fall into categories.
Plastic lattice bases
These generally come as 12inch tiles that you join togetherto make the size of base you require. They are marketed along the lines of youcan assemble them anywhere without any preparation. Although this is true ifthey are placed on a completely flat surface, the bases work and look better ifyou put a little work in.
The plastic lattices can be used without gravel, but I thinkthey look better with gravel. The gravel also provides extra strength andshields the plastic from the sun’s UV rays. Unlike the wooden joists we usedabove, they will last for many years.
Look for products that are made from recycled plastic. Theyare as good as non-recycled and are of course, better for the environment.
Building a base with pre-fabricated plastic tiles
Remove any turf and dig down to the same depth at the plasticlattice – typically only a couple of inches. As with the gravel base, I wouldlay the water permeable landscaping cloth to stop weeds growing. Once theplastic tiles are in place, fill with gravel before installing the hot tub.
Another option would be to install the hot tub and then fillthe exposed lattice with a mixture of topsoil and coarse sand. You could thensow grass seed, giving the impression that the hot tub was just put on thelawn. The sand will ensure there is adequate drainage around the hot tub, sopuddles that could damage the hot tub’s cabinet shouldn’t form. You could do asimilar thing with wooden bark or decorative stones.
The other type of prefabricated base is a solid plastic base
These are designed to lay on flat turf, compact soil, gravelor paving, and help distribute the weight of the hot tub evenly. As with theplastic lattice tiles, the manufacturers claim they will mean you have lesswork to do, as you do not need to prep the ground. This claim is only valid ifthe soil is entirely flat; if this is not the case, then you will have to levelthe ground first.
Think drainage!
I do not recommend you place your hot tub on flat turf orcompact soil unless the drainage is impressive. When people exit the hot tub, alot of water drips off of them, which will cause puddles and potentially damagethe surrounding lawn.
If you want to give the impression that the hot tub isdirectly on the lawn, then I would recommend you use the plastic tiles,detailed above, with a sand/soil mix that will aid the drainage.
Installing the solid plastic base
To get the best out of this product, I would remove thetopsoil from the area that I wanted to position my hot tub. I would line thehole with permeable landscape cloth and fill with crushed rock. This cloth willstop any drainage issues and will allow us to get the surface completely flatbefore we cover the gravel with the solid plastic base.
Placing the Hot tub on a patio
Placing a hot tub on an existing patio is a sensible,cost-effective way to install your hot tub. Patios are generally constructed atthe rear of a property, which is ideal for easy access to your hot tub. You aremore likely to use the hot tub if it is easily accessible.
The winter is the most fabulous time to use the hot tub, but you need to take some precautions to make sure you stay safe. Having your hot tub on the patio will make jobs like removing snow from the hot tub cover and ensuring clear passage to the house easier. For more details on winter hot tubbing, click here.
Disadvantages of placing your hot tub on a patio
Unfortunately, many patios are constructed at a slightincline to allow for the water to drain away. If this is the case, placing yourhot tub on this surface may damage it in the long term.
Patios that do not have an incline tend to get puddlesforming after rainfall. If your patio does this, you could use a plastic base,which will raise the hot tub out of the water, so it is less likely to be damaged.
Paving stone base
You can build a paving stone base for your hot tub;effectively building the hot tub a patio! I am not a fan of this as the workinvolved is more than gravel or even a concrete base, and the result may not beas good. Paving stones are more likely to move independently of each other,making the base uneven.
Hot tub decking base
I think hot tubs look fabulous on wooden decking. It softenstheir appearance, and, when built well, makes the hot tub blend with thelandscape. Building simple decking is straight forward even for a novice DIYenthusiast.
Intricate decking designs, where the hot tub appears partially sunk with multiple raised decking areas, will need to be at least planned by a professional structural engineer. However simple flat decking designs can be designed with a ruler, some paper, a pencil and a measuring tape!!
Building a decking base
When I constructed my decking, the planning took a couple ofhours, and the decking was built over two weekends. It took a long time becauseit needed to fit around the rear of the house and around four trees! A simpleeight-foot square decking construction can be quickly completed in oneafternoon by one person with the correct tools.
Getting the correct spacing of the joists, beams andfootings is vital to the stability of the decking. The resource I used to help me plan out mydecking was www.decks.com. They havethousands of articles to help you build your decking. They have some fancybuilds, but if this is the first decking you are making, maybe keep it simple!!
Tips for building a decking hot tub base
The primary advice I can give is to get the frame right.Many people are in a rush to start to lay the decking planks, but spending thetime to get the base flat and secure is the most vital part. I over-engineeredmine, having more footings than required and putting the beams closer thanneeded, but what this has resulted in is incredibly durable decking!!
The other tip that will save you so much time is to use anelectric drill and have at least one spare battery. If possible, it is handy tohave two drills. Having two drills will stop you having to change the drill bitfor the different screws.
Inflatable hot tub base
Inflatable hot tubs should be installed on flat surfaceslike solid hot tubs. However, a slight incline 1-2 degrees is not a problem. Myfirst hot tub was an inflatable, and I placed it on some existing paving, whichwas on a very slight incline to allow for rainwater to run off. The slopecaused no issues whatsoever.
If you are planning to use your inflatable hot tub in coldweather, you may want to think about a base that is insulated. Inflatable hottub manufacturers sell a base that has some insulation qualities, but it ismainly designed for comfort.
Rubber bases
There are thick rubber tiles on the market that make an excellent insulated base, but before you go and spend a lot of money on them, think about how much they will save you in energy. I would suggest, not a lot because most of the heat is lost from the surface of the water so you might be better off buying something to insulate that more effectively. I have detailed some ideas for this in the following article – cold weather hot tubbing tips!
What is the best base for a hot tub?
The best base will depend on where you are planning to placeyour hot tub and what your budget is. The most cost effective is a crushed-rock/ gravel base, and I think this, combined with the plastic tiles, provides thebest long-term solution.
If you want any more information, please feel free tocontact me directly. If you can add to the conversation, leave a comment below!
Enjoy your day!
Brendan
😊
FAQs
What is the best foundation for a hot tub? ›
Concrete Base
Concrete makes a fantastic foundation for any top thanks to its long-lasting durability and sturdiness. For many hot tub owners, concrete bases are the preferred option as they are both economical and functional.
Gravel Base
Dig out an area several inches deep and make sure the ground at the bottom is pressed flat. Fill the hole with gravel and press it down to make sure it will not shift or sink once it has weight on it. The gravel will conform to the shape of the bottom of your tub to hold it firmly in place.
Gravel makes an excellent base for a hot tub (also an excellent above-ground pool base material). Generally, gravel hot tub pads work best when using a combination of larger crushed rock for a supportive base and smaller landscaping gravel or pea gravel for a surface layer.
How deep should a foundation be for a hot tub? ›Concrete Base For Hot Tub
You will need to start by excavating an area that is big enough for your hot tub, plus some extra inches. With concrete you won't need to dig as deep, four inches will suffice. You will need to use 2×4 inch boards to build a frame inside the pit.
Remember: spas are heavy, your deck will need to support at least 140#'s per square foot, that equals a load of 6860 pounds!
What structure do you need to support a hot tub? ›Standard 4x4 posts can be used for supports, and 2x8 joists will support the weight of most typical hot tubs. Check local building codes for footing requirements. Twelve inch on center spacing between joists underneath the hot tub will help provide extra support and 2x6 decking is preferred.
How deep does a concrete base need to be for a hot tub? ›The concrete base needs to be a minimum of 4 inches thick (ideally 6 inches) so it is able to withstand the weight of the hot tub. It is also a good idea to place rubble to the foundation for maximum support or reinforce the concrete base with rebar.
What can a hot tub sit on? ›A hot tub requires a stable surface — whether it's a concrete slab, reinforced deck, or firmly compacted soil with crushed gravel. There's also the option to have the hot tub installed in the ground but that still requires a concrete vault.
Does a hot tub need a solid base? ›Hot tubs are heavy and it is important to ensure the base is solid in order to support the weight.
Can I use pavers for hot tub base? ›Pavers are attractive and can be used as a hot tub base, with a few precautions. As some pavers are raised in height, this can impact how level the base is and cause problems down the road for your hot tub frame and shell.
Can you use pavers as a base for hot tub? ›
Pavers can be an attractive option for a hot tub, but there are a few disclaimers you should consider. The main factor to consider is raised pavers which can cause problems at the base and put stress on the hot tub shell. To avoid this issue, select pavers that are smooth and interlock so there is a flat surface.
What is the 5 foot rule for hot tub? ›*The National Electrical Code (NEC) specifies installation of an approved manual disconnect device. It must be adjacent to the hot tub, at least 5 feet away, and within line of sight. The NEC also requires a 120V receptacle within a 10-20 foot distance from the spa.
How high can hot tub be off the ground? ›Typically, there's not a standard height for hot tubs. But there is a standard range. Most hot tub walls fall between 34 and 42 inches high.
What kind of slab do I need for a hot tub? ›The minimum thickness safety requirement for a basic hot tub pad is 4″ thick reinforced concrete with a diameter of 6″ less than the diameter of the bottom of the tub. Therefore, a 5′ round straight sided wood hot tub would require a 4′ 6″ square pad.
Is it better to put a hot tub on pavers or concrete? ›Pavers as a Quick Solution
If concrete is an option you're not interested in, pavers may be the route to go. While pavers are not as durable or strong as concrete, they are versatile and relatively cheap compared to pouring a concrete slab. If you go this route, ensure your hot tub has a flat bottom.
Can I put a hot tub on dirt or in the grass? A hot tub should not be placed on soil or on a lawn. Instead, it will need a solid platform to support all of the weight. Exposure to wet soil and grass will reduce the life of your hot tub and expose it to insects and moisture.
What kind of gravel do you put under a hot tub? ›Check for level again, then add up to two inches of your choice of smooth, natural pea gravel. Once you've got the pea gravel tamped down and leveled, you are ready to place your hot tub on the base. Simple, quick, and effective. With a combination of crushed stone and pea gravel, you get the best of both worlds.
How much support do you need under a hot tub? ›To ensure optimal support, your hot tub should be installed over at least one support beam, which is likely placed every few feet below your deck. Without well-positioned support beams or posts, your deck will be unable to hold the hot tub's weight. In such a case, you can have load-bearing support beams added.
How far does hot tub need to be off wall? ›To protect your home and outbuildings from potential flooding, keep it at least 5 feet from any structure. Also, locate the spa close to a doorway into the house or provide a small changing area close by for wintertime use.
How far should a hot tub be from the house? ›Although it's important to ensure your hot tub is accessible for all those who will use it, it's essential to remember that your hot tub or spa is some distance from your home. Although it may change from location to location, typically speaking, you will want to keep about 5 feet of distance between your spa and home.
How much room should you have around a hot tub? ›
Space. There must be enough room not just for movement or getting in and out of your tub, but also for maintenance. You'll need to choose a location that allows for easy access to the inner workings of the hot tub. We recommend leaving at least 30 inches around all sides and back panels of the hot tub.
How thick should a hot tub slab be? ›The minimum thickness safety requirement for a basic hot tub pad is 4″ thick reinforced concrete with a diameter of 6″ less than the diameter of the bottom of the tub. Therefore, a 5′ round straight sided wood hot tub would require a 4′ 6″ square pad.
Should I put anything under my hot tub? ›A level base will ensure your Hot Tub transfers the weight of its contents through the structure correctly. This will prevent any warping and any unnecessary strain on the tub. It'll also mean the water doesn't spill out of one side!
How much weight can pavers take? ›Pavers can withstand at least 8,000 pounds of pressure per square inch before material failure. As previously mentioned, this makes pavers about four times stronger than poured concrete.
Can you put a hot tub directly on a patio? ›Your hot tub can be placed just about anywhere—outdoors or even indoors when practical. You can put it on a deck, patio, rooftop entertaining area, or even under a gazebo.
What can I use instead of paver base? ›Yes, you can use sand for a paver base. A sand set installation method may be best if a concrete slab is not an option for the base. This system offers permeability and some flexibility.
What can I use as a paver base? ›Crushed Stone
Stone aggregate comes in a variety of sizes, but most experts recommend 3/4-inch gravel for paver bases. Crushed stone makes a solid paver base because it allows water drainage and is easy to work with.
The traditional base for a paver patio is 4–6” of compacted gravel above your dirt. If you're installing a driveway or road intended for vehicular traffic, you'll need to double the thickness of your gravel layer.
How much shock do I need for a 400 gallon hot tub? ›Take every preventive safety measure and start adding shock treatment to the hot tub water. The amount of shock treatment you need will depend on how much water is in your hot tub, but a good rule of thumb is to add one pound of shock for every 10,000 gallons of water.
How many times can you shock your hot tub in a row? ›In essence, shocking your hot tub means adding a higher than usual dose of oxidiser chemicals to the water. This is also known as oxidising. We advise everyone to shock their water once a week to reduce bacteria and impurities. You can do this with one of two products; chlorine shock or non-chlorine shock.
Why can't you stay in a hot tub for longer than 15 minutes? ›
Since the water in a hot tub is higher than your normal internal temperature, staying in a hot tub too long can cause you to overheat and experience symptoms like light-headedness, dizziness, or nausea.
What is the most popular hot tub size? ›Medium hot tubs: The most popular hot tub size is 84″ x 84″, which is about 7 feet by 7 feet.
What can I use instead of concrete slab for hot tub? ›Along with traditional concrete slabs, some options can save you time and money. For example, gravel and pavers are cheaper and give good drainage. A wooden deck is an elegant and comfortable solution. Prefabricated spa pads save you time and money on construction.
What is the best floor for a hot tub room? ›It is essential to use ceramic porcelain tile or sheet vinyl on the floor of the room and avoid the use of any type of carpet. A carpeted surface supports the formation of mold in areas that are damp. Tile flooring is easier to clean and can be bleached to kill mold.
What is the cheapest way to pour a concrete slab? ›Working With Ready-Mix Concrete
And, if you mix it yourself, it's the cheapest way to make your slab. For most do-it-yourselfers, the best material for building a concrete slab is a ready-mix, crack-resistant concrete product. The wet mix is poured into a prepared wood form, then left to cure.
Pavers as a Quick Solution
If concrete is an option you're not interested in, pavers may be the route to go. While pavers are not as durable or strong as concrete, they are versatile and relatively cheap compared to pouring a concrete slab. If you go this route, ensure your hot tub has a flat bottom.
A hot tub requires a stable surface — whether it's a concrete slab, reinforced deck, or firmly compacted soil with crushed gravel. There's also the option to have the hot tub installed in the ground but that still requires a concrete vault.
What kind of surface does a hot tub need to sit on? ›Outdoor hot tub placement, such as decks, concrete or brick patios, is common. However, the hot tub can be placed on any solid, uniform, level surface. Do not place your hot tub on grass or bare ground.
How many inches of concrete do I need for a hot tub? ›The minimum thickness safety requirement for a basic hot tub pad is 4″ thick reinforced concrete with a diameter of 6″ less than the diameter of the bottom of the tub. Therefore, a 5′ round straight sided wood hot tub would require a 4′ 6″ square pad.
Are pavers strong enough for a hot tub? ›Pavers are attractive and can be used as a hot tub base, with a few precautions. As some pavers are raised in height, this can impact how level the base is and cause problems down the road for your hot tub frame and shell.
Do you need anything under a hot tub? ›
A level base will ensure your Hot Tub transfers the weight of its contents through the structure correctly. This will prevent any warping and any unnecessary strain on the tub. It'll also mean the water doesn't spill out of one side!
Should hot tub be against house? ›Having your hot tub right next to the wall of your home is probably too close. The steam that comes from the water may seep into windows and water splashed from the tub may cause a slippery walkway. A few feet away from your home and a few feet away from your walkway is typically the ideal combination.
Is it OK to drain hot tub water on lawn? ›Provided that the chlorine level was zero when you drained your hot tub water, you can use the water to safely water your trees and shrubs. If you would like to also use it to water your lawn, just make sure to check the pH level first as grass can be more sensitive.
Where is the best place to put a hot tub outside? ›'A location that offers both a beautiful view and affords you some privacy is usually best,' advises BISHTA. So, a fenced or covered patio or decking area is usually best, although a living hedge will usually also offer enough protection.