Can You Put a Hot Tub on Flagstone? (Yes, but don’t use . . .)

A lot of hot tub owners think you have to put your hot tub on a concrete pad. However, there really are many other options. But one lesser-known option that gets asked about is can you put a hot tub on flagstone?

I decided to look more into it and here is what I discovered.

Yes, you can put a hot tub on a flagstone. However, sedimentary sandstone can be problematic as moisture is easily absorbed and cause the sandstone to flake. Chlorinated water can damage it also. Metamorphic sandstone, such as quartzite provides a better surface for a hot tub over the long term.

However, Flagstone is not the only option and within the category of flagstone, there are many options.  There are many more foundations that might be compatible with your needs. Continue reading to explore more on these. 

What’s the best base for a hot tub?

Concrete is an excellent base for your hot tub as it is extremely sturdy and long-lasting- if prepared correctly.

A bare ground location of soil or clay cannot indefinitely support the weight of a permanent hot tub that weighs around 5,000 pounds. When filled with water, all this weight sits on a footprint of just 12 square feet.

The ground area where your hot tub will be placed should be well leveled and a professionally recommended foundation prepared. The base will need to be one or a combination of the following; flagstone, concrete, crushed stone or pea gravel, pavers, or a deck with engineered structural support. 

If you are a first-time hot tub buyer and have made the decision to install a tub, my recent article about why, and how to make sure your hot tub is level is crucial.

Just click that link to read it on my site.

One of the major importance is having a base that will not allow the hot tub to move. An unstable base places a great deal of stress on the tub frame and the shell itself. Once it is full of water and people, the chances of shell warping or cracking increase on a poor base. 

Keep in mind; ground varies from location to location. If your home is situated on low-lying land with soft soil and possibly subject to flooding, you will have more to consider than if you live on higher ground with a rock or rocky ground.

Do you have to put a hot tub on concrete?

The answer is no. Is concrete based recommended? Yes; however, there are less expensive and almost as reliable alternatives as provided in the answer to the previous question.

A permanently located hot tub needs a solid platform to support the combined weight of the tub, the water, the occupants, and the movement of the water in the hot tub, the latter being something not often considered. When water sloshes around in a confined space it can exert considerable force. Think of a wave pool for example.

The best hot tub foundation should be solid, uniform, and level. Many professional installers or hot tub owners who have well researched their hot tub installation generally add an extra foundational layer and ensure it extends beyond the hot tub base at least six inches on all sides.

If using concrete, the ideal base is a four-inch to six-inch thick pad installed on a base of four inches of crushed gravel.

Again, this depends on the type of land your house is located on. To learn more about using a concrete base, please check out our recent article. I not only get into concrete but all the more cost-effective alternatives including 1 that is just pennies on the dollar compared to concrete.

Just click that link to read it on my site.


Is flagstone cheaper than concrete?

Laying paving stone will cost around $30 a square foot but that is dependent on the type of flagstone you use.

A good concrete base for a standard model hot tub will run you around $15 – $20 a square foot. Therefore, the cost for your base using stone could be twice that of concrete, all dependent on what type of stone you use. If you are installing a large party hot tub, the cost differential could be substantial.

Many prospective hot tub owners choose to use other materials such as concrete, bricks, or gravel due to the higher cost of flagstone. Also, mortaring flagstones on top of a concrete slab is typically more expensive than dry laying the stones over a base of sand and gravel.

Many people like the look of flagstones, thanks to the many options that are available that make it easier to find the perfect style to match your garden decor. 

The following are some of the flagstone choices available:

Sandstone:

This stone is available in various shades and colors. It has cooler surface temperatures in summer and is weather-resistant. However, it should be sealed to avoid staining.

Quartz:

Quartz is available in various shades and colors. It is resistant to rain, wear and tear, and harsh chemicals.

Bluestone:

This attractive stone also comes in various shades and colors. It is dense and holds up better in harsh winters. It does require proper sealing to preserve its color.

Limestone:

Always a popular choice with its availability in various colors, limestone is good for humid climates. It is both weather-resistant and long-lasting.

Travertine:

Travertine is very durable but is a higher-end stone. It can be difficult to finish and maintain because of surface pits. It also comes in various subtle shades.

Basalt:

Basalt comes in natural grays, beige or black and has great sound absorption. It can become dull-looking over time.

Slate:

Slate is very common and is easy to chisel and shape. It splits easily, has limited availability in large sizes, and requires sealing for stain resistance.

Quartzite Flagstone

Flagstone comes in a lot of different grades. Many of the softer kinds flake easily, absorb water quickly, and don’t handle chlorinated water well at all.

Luckily, quartzite flagstone isn’t one of those!

Quartzite comes in tons of color choices, and rates really high on the carbon hardness scale. Looking for a flagstone patio for your hot tub? This is the one to get!


Is there a cheaper alternative to flagstone?

Many prospective hot tub buyers when considering using flagstones ask this question.

And the answer is a definitive yes! Every other option for a hot tub base is less expensive than flagstone but if you like the look and you plan on staying in your home well into your retirement, it’s a great choice.

One way of looking at the cost is to amortize it over 20 years.

A hot tub’s life-span is based on a combination of two factors – the quality of the tub and care. A hot tub can last anywhere from 5-20 years or more, mostly dependent on the price and the brand you choose.

Lower end cost hot tubs are made with lower quality materials and you can only expect to get six to seven years of use.

If you buy a lower cost unit and don’t maintain it as per the manufacturer’s requirements, they may not last more than 5 years. Therefore, if you buy a top of the line hot tub that you can get twenty years to use and a flagstone base, your cost per year can be quite reasonable.

How long are you staying in your home should be one of the deciding factors when selecting a hot tub.

If you plan on staying well into your retirement then a top-quality tub and the base makes the most sense. To get additional facts if you are a first-time buyer, please check out our recent article on buying your first hot tub.

I get in 23 of the most crucial tips you need to know including the best time of year to get the lowest price. Just click that link to read it on my site.


How much aggregate base do I need for a hot tub on flagstone?

Drainage can be compromised without enough gravel or aggregate.

With too much, the hot tub base may become unstable and cause damage to the tub over time particularly if your home is located in an area where you receive a lot of rainfall and where the ground may be soft. Four to six inches is considered a good range.

After measuring and marking, remove any turf, and dig the hole for the hot tub base. It is a good idea to solidly tamp the ground down before installing the aggregate. Make sure you are digging at least six to eight inches down for the base.

Line the bottom of the excavated area with landscape cloth, cutting it to size with scissors.

If you need more than one piece of cloth, overlap the edges of the pieces by three to four inches. Place a minimum of four inches of medium-grade construction gravel on top of the landscape cloth, and rake it so the top is smooth and level before installing the flagstones as per the manufacturer’s instructions.

Did I cover all you wanted to know about whether you can put a hot tub on flagstone?

The big advantage of flagstone is the wide variation of color.

There is a flagstone type of just about every shading that will complement most garden landscapes. Other advantages are their longevity and the quality look. As mentioned in previous posts and something that cannot be stressed too much, building the base correctly the first time is the key to many happy years of hot tub enjoyment.

The right base will enable your hot tub to last longer, be more economical and more comfortable to use. The wrong base could lead to expensive damage to your hot tub or property and possibly your guests.

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Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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