Will 4 inches of concrete hold a hot tub?

Author: Kirk Schaden  |  Last update: Sunday, September 28, 2025

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. The type of ground underneath the pad should be stable as well.

Can you put a hot tub on a 4 inch concrete slab?

How Thick of Concrete Do I Need for My Hot Tub? As a general guideline, a concrete pad should be at least 4 inches thick. Additionally, your concrete hot tub pad should be reinforced with either rebar or mesh. The rebar and mesh should be attached to a bond wire for electrical grounding purposes.

How much weight can 4 inches of concrete withstand?

Typical Weight Capacity: A well-constructed 4-inch concrete driveway can typically support weights ranging from 4,000 to 6,000 pounds, which is sufficient for most passenger cars and light SUVs.

How thick should a concrete slab be to hold a hot tub?

A hot tub base should be strong enough to bear up to 115 pounds/SQF. To withstand this much weight, the concrete slab should be a minimum of four inches thick. But beyond its thickness, other factors influence the strength of your concrete slab. The concrete slab must be completely level.

How deep does a concrete base need to be for a hot tub?

Your base can be made to fit the size of the hot tub or made larger to create an area to walk around on or install steps/furniture etc. 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.

Best Foundation Type for your Hot Tub

Can a hot tub sit directly on concrete?

You can ensure your hot tub has a durable, level surface by pouring a new solid concrete slab in any location in your backyard. Concrete slabs are one of the oldest and most reliable choices for a hot tub base.

How deep to dig for hot tub base?

Remove all the grass and dig down at least 6 – 8 inches to prepare the base for your concrete spa pad. layer with crush stone and wire mesh to keep the concrete from shifting or cracking. Pour your concrete and finish level for your hot tub water line to be level when in place.

How long does concrete need to cure before a hot tub?

Use. You can walk on your concrete 24 hours after the concrete is poured, cars and light pickup trucks 7 days after concrete is poured, and heavy equipment and campers 28 days after pour. For patios, you can place patio furniture on the new concrete after 3 days, and a hot tub after 1 week.

Should I put gravel or concrete under my hot tub?

Gravel is an excellent choice for a hot tub base. It's relatively cost-effective and easy to install, plus it's very good for drainage. This is important because you need to make sure any rain water or overspill from your hot tub is able to drain away from the base. And unlike concrete, gravel won't crack over time.

Is a hot tub too heavy for a patio?

As a general rule of thumb, if you have a deck that's raised only a couple feet or less, it can support about 100 pounds per square foot. So, if the spa is less than 100 pounds per square foot you likely have nothing to worry about.

Is 4 inches of concrete enough?

For residential driveways, a common recommendation is a minimum thickness of 4 inches (10 centimeters). This thickness is suitable for regular passenger vehicles and provides adequate strength and durability.

Can you put a hot tub on stamped concrete?

Stylish Look- If you want your hot tub to look good, you have different styling options with concrete. Stamped concrete allows you to customize your outdoor spa area to your liking. Replicate the look of brick, stone, or wood and complete your outdoor living area!

How much weight will a 4 inch concrete driveway support?

Concrete driveways are typically poured four inches thick, giving the concrete driveway enough strength to withstand loads of regular vehicles (up to approximately 8,000lbs).

Can my floor support a hot tub?

The floor load of a hot tub filled with water is around 115 lbs. per square foot. Your base should have at least 125 lbs.

What slabs are best for hot tub?

Concrete slabs are among the most durable and reliable bases for hot tubs. They offer excellent support and longevity, ensuring your hot tub remains stable for years. To prepare a concrete slab, you'll need to excavate the site, build a frame, pour the concrete, and level it.

How much does a hot tub weigh?

In general, a small two-to-three-person hot tub will typically weigh 500 pounds when empty, and somewhere near 3000 pounds when filled with water. If your spa is of a much larger variety, such as a nine or ten-person spa, the dry weight will be somewhere in the ballpark of 900-1250 pounds, and up to 8000 pounds filled.

How deep should concrete be 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. The type of ground underneath the pad should be stable as well.

What 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.

Can concrete hold a hot tub?

Concrete pads are great for hot tubs because they provide a solid foundation that's resistant to weather and will not shift over time. They also don't require additional framing or support, so installation is relatively simple.

Do I need rebar in concrete slab for hot tub?

The primary purpose of rebar in a hot tub concrete slab is to distribute and withstand the pressure and weight exerted by the hot tub, especially when it is filled with water and occupants. The weight of the water and people inside the hot tub can put significant stress on the concrete slab.

How much does a concrete slab for a hot tub cost?

The cost of your hot tub foundation can range from 0-$1,000+ depending on if you already have a solid foundation, or if you decide to build a custom deck for your hot tub. For reference, spa pads range in price from $100 to $500, and concrete slabs range from $900 – $2,000.

How hot is too hot for concrete to cure?

First things first, if it's hot enough where you don't want to leave the comfort of your air conditioning or cold enough that you need to put on a hat and gloves, you shouldn't lay concrete! It's advised that concrete be cured at a moderate temperature between 50 °F – 90 °F.

Can you put a hot tub directly on gravel?

We recommend a gravel base as the best all-around hot tub base, particularly if your hot tub will be installed in an area that doesn't already have concrete or pavers. (Technically, your hot tub should be installed on crushed stone “gravel”, not actual river gravel, which won't tamp down properly.)

Do you need a permit for above ground hot tub?

Although building codes vary by state in the U.S, typically a building permit is only required for a swim spa or hot tub with a water capacity of more than 5,000 gallons which exempts most spas.

What is best to put under a hot tub?

6 Best Hot Tub Foundations For Your Spa
  1. An Existing Deck. If you wish to install your new hot tub on an existing deck, you must first ensure the structure will bear the spa's weight. ...
  2. An Existing Patio. ...
  3. Concrete Slab. ...
  4. Crushed Gravel. ...
  5. Paver Stones. ...
  6. Prefabricated Pad.

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