Key facts
- Water weighs about 8.34 lb per gallon. A 300 gallon tub holds about 2,500 lb of water.
- Hot Spring lists its Hot Spot tubs at 95 to 125 lb per square foot, including occupants at 175 lb each.
- IRC deck design loads are 40 psf live plus 10 psf dead, per the American Wood Council.
- The AWC says concentrated loads such as hot tubs are beyond the scope of its DCA 6 deck guide and need a design professional.
- Hot Spring recommends a reinforced concrete pad at least 4 in. thick, or a deck rated for the tub's listed psf.
Sources: Hot Spring's Hot Spot pre-delivery instructions; MyHotTub product pages for the Victoria, Mazara, Mesa, Sierra, Corona, Luna and Terra; and the American Wood Council's deck load FAQ and DCA 6 article.
Hot Spring's published numbers
Hot Spring is one of the few makers that prints pounds per square foot in its install instructions. Its filled weights include a full load of people at 175 lb each.
| Model | Size | Seats | Gallons | Filled weight with occupants | Listed load |
|---|---|---|---|---|---|
| Rhythm | 7'0" x 7'0" | 7 | 330 | 4,820 lb | 125 psf |
| Relay | 7'0" x 7'0" | 6 | 340 | 4,715 lb | 120 psf |
| Pace | 6'10" x 6'10" | 5 | 300 | 4,150 lb | 115 psf |
| SX | 6'0" x 6'5" | 3 | 230 | 3,090 lb | 105 psf |
| Stride | 7'0" x 5'5" | 3 | 225 | 2,975 lb | 100 psf |
| TX | 6'0" x 6'0" | 2 | 190 | 2,570 lb | 95 psf |
The smallest tub on that list is still more than twice the 40 psf live load a standard deck is designed for.
The models we carry, worked out
MyHotTub publishes dry and filled weights but not pounds per square foot. Its filled weights match dry weight plus water, so they do not include people. We divided by each footprint, then added occupants at Hot Spring's 175 lb per seat. These are our calculations from the maker's specs.
| Model | Footprint | Filled weight (maker) | Water only | With every seat full |
|---|---|---|---|---|
| Victoria, 480 gal | 91 x 91 in. (57.5 sq ft) | 4,813 lb | About 84 psf | About 102 psf (6 seats) |
| Mazara, 400 gal | 85 x 85 in. (50.2 sq ft) | 4,082 lb | About 81 psf | About 102 psf (6 seats) |
| Mesa, 300 gal | 74 x 74 in. (38.0 sq ft) | 2,933 lb | About 77 psf | About 105 psf (6 seats) |
| Sierra, 360 gal | 82 x 82 in. (46.7 sq ft) | 3,422 lb | About 73 psf | About 96 psf (6 seats) |
| Corona, 270 gal | 80.5 in. round (35.3 sq ft) | 2,675 lb | About 76 psf | About 105 psf (6 seats) |
| Luna, 222 gal | 69 in. octagon (27.4 sq ft*) | 2,061 lb | About 75 psf | About 107 psf (5 seats) |
| Terra, 216 gal | 70.5 x 61 in. (29.9 sq ft) | 2,046 lb | About 69 psf | About 92 psf (4 seats) |
*We treated 69 in. as the width across the flat sides of the octagon. Notice that the small round and octagonal tubs land at the same load per square foot as the big square ones: less water, but on a smaller footprint. A smaller tub is not automatically easier on a deck.
Why "about 2,000 pounds" is the wrong question
Total weight matters for posts and footings, but load per square foot is what you compare with the deck's design load. The IRC designs decks for 40 psf live load, the weight of people and furniture spread across the surface, plus 10 psf for the deck itself. A tub concentrates 70 to 125 psf on one patch, for months at a time. That is why the American Wood Council's prescriptive deck guide, DCA 6, does not cover hot tubs and tells you to bring in a design professional. Watkins Wellness, which makes Hot Spring, says the same: consult a structural engineer or qualified contractor before placing a spa on an elevated deck.
An engineer will look at joist size and spacing under the tub, beam spans, post sizes, footings and the ledger connection to the house. A common answer is a framed section with extra joists and a beam and footings directly under the tub, designed for the tub's listed load.
On the ground: pad options
- Concrete slab. Hot Spring calls a slab best for long-term use: reinforced, at least 4 in. thick, sloped about 1/2 in. per 10 ft for drainage.
- Pavers or brick. Acceptable to Hot Spring if leveled under the entire spa. A paver base needs proper compaction so it does not settle unevenly.
- Wood decking at grade. Hot Spring allows it if leveled under the whole tub, but warns that water standing under a spa for long periods can rot wood.
Hot Spring is clear that providing a level foundation is the owner's job, and that delivery crews usually cannot level a site. Damage from an inadequate foundation is not covered by its warranty. Plan the pad before the delivery date.
A quick checklist
- Get the maker's dry weight, gallons, seats and footprint, or its published psf.
- Work out psf with every seat full. Use the real footprint for round and octagonal tubs.
- On a deck, have a structural engineer or qualified contractor confirm or design the framing, and ask your building department about permits.
- On the ground, pour or prepare a level pad and leave access to the equipment side of the tub.
- Plan the electrical at the same time. See 120V plug and play vs 240V hot tubs.
Related guides
- Plug and play 120V vs 240V hot tubs: which do you need?
- Can a deck hold a cold plunge?
- Can you put an outdoor sauna on a deck?
- Barrel sauna foundations: gravel, pavers or concrete
- Shop hot tubs
Frequently asked questions
Can a normal deck hold a hot tub?
Usually not without added framing. A deck built to the IRC is designed for a 40 psf live load plus a 10 psf dead load. Hot Spring lists its Hot Spot tubs at 95 to 125 pounds per square foot filled with people in them, and the MyHotTub models we sell work out to roughly 69 to 84 psf with water alone. The American Wood Council says concentrated loads like hot tubs are outside its prescriptive deck guide and need a design professional.
How much does a filled hot tub weigh?
Roughly 2,000 to 5,000 pounds for a 4 to 7 person tub, before people. A gallon of water weighs about 8.34 lb, so a 300 gallon tub holds about 2,500 lb of water. MyHotTub lists its Mesa at 2,933 lb filled and its 480 gallon Victoria at 4,813 lb filled. Add about 175 lb per occupant, the figure Hot Spring uses.
How do I work out pounds per square foot for my hot tub?
Add the dry weight, the water (gallons times 8.34) and the occupants (seats times 175 lb, or your own number), then divide by the footprint in square feet. Use the real footprint: a round or octagonal tub covers less area than its width squared. Some makers publish this number for you; Hot Spring does in its pre-delivery instructions.
What is the best base for a hot tub on the ground?
A level concrete slab. Hot Spring recommends a reinforced pad at least 4 inches thick, sloped about 1/2 inch per 10 feet so water runs off and does not sit under the tub. It says other bases can work if they are level, but structural damage from an inadequate foundation is not covered by its warranty.
Can I put a hot tub on pavers or gravel?
Some makers allow it if the base is compacted, level and supports the whole bottom of the tub. Hot Spring says if brick or wood is used, it should be leveled under the entire spa. Check your maker's manual, because the warranty depends on following its foundation requirements.
Do I need a permit to put a hot tub on a deck?
Often yes, for the structural work and for the electrical connection. Reinforcing or building a deck for a hot tub generally needs an engineered design, and new circuits need an electrical permit. Ask your local building department before you order.
Keep reading
Browse our hot tubs collection, see all guides, or ask us a question about your project.