Do I need a concrete slab for a hot tub?
You do not need a concrete slab by name, but you do need a flat, level base under the whole tub. Liberty Spas recommends one that supports at least 150 lb per square foot, such as a 4 to 6 inch poured concrete pad, in full contact with the bottom of the spa.
That recommendation comes from the product pages of the five models in our hot tubs collection, and we sell all five, so we have a stake in how this goes. The short version: a filled hot tub is heavy, the weight sits on a small footprint, and the base has to carry it evenly for years. This guide shows the weights, explains what the base must do, and lists what to settle before a tub is delivered. It is planning information, not engineering advice.
Why does the base matter so much?
A hot tub is mostly water. The weights below come from our product pages, and the last column is simple arithmetic: filled weight divided by the footprint of the outer dimensions. It is a rough average, not a design load, because the weight is not spread evenly. The seats, the equipment bay and the water depth all change where the load sits.
| Model | Outer size | Dry weight | Filled weight | Rough average | Price |
|---|---|---|---|---|---|
| LYS4000 | 84" x 60" | 450 lb | 2,050 lb | about 59 lb per sq ft | $6,000 |
| LYS4500 | 78" x 78" | 640 lb | 2,850 lb | about 67 lb per sq ft | $5,500 |
| LYS5000 | 79" x 79" | 850 lb | 3,280 lb | about 76 lb per sq ft | $6,500 |
| LYS6000 | 84" x 84" | 850 lb | 3,280 lb | about 67 lb per sq ft | $7,499 |
| LYS7000 | 84" x 84" | 900 lb | 3,500 lb | about 71 lb per sq ft | $7,499 |
The filled weights do not include the people sitting in the tub. Liberty's 150 lb per square foot figure is well above these averages, which leaves room for people and for uneven loading. Confirm every figure on the product page before you plan, because specs can change.
What does Liberty Spas say the base should be?
The same line appears on all five product pages under "Prepare the base": a flat, level base that supports at least 150 lb per square foot, such as a 4 to 6 inch poured concrete pad, in full contact with the bottom of the spa. Three parts of that sentence matter.
- Flat and level. A tilted tub strains the shell, and the water line will look crooked from the first day.
- At least 150 lb per square foot. This is the capacity of the base, which is a question for whoever pours or builds it.
- Full contact with the bottom. The tub should rest on the base along its whole underside, not on a few corner points with air underneath.
A poured pad is the example Liberty gives, so it is the one we plan around. If you want to use something else, ask Liberty to confirm it meets the same standard before you order.
Can you use a deck, pavers or gravel instead?
Our product pages name only the poured concrete pad, so we cannot tell you that another base is approved. What we can say is the test it has to pass: flat, level, at least 150 lb per square foot, and in full contact with the underside of the spa.
A wood deck is the case that needs the most care. Ordinary decks are often built for people and furniture, not for a tub that weighs more than 2,000 lb filled, so ask the deck builder or a structural engineer to confirm the framing and footings in writing. Loose gravel or a paver surface can settle unevenly over time, which breaks the full contact and level requirements. If a base cannot show you it meets the standard, a poured pad is the safer plan.
How big should the pad be?
At minimum it must cover the outer dimensions in the table. Our pages list only the size of the tub itself, so the extra room is your decision. Think about a step or a place to set a towel, a path for the person who services the equipment, and where the cover will rest when it is lifted off. If you are still choosing a size, our what size hot tub do I need guide walks through seats and space before you pick a pad plan.
What else should you settle before delivery?
The base is one of four things to settle before the tub arrives.
- Power. The LYS4000 and LYS4500 plug into a standard 120V, 15A dedicated GFCI-protected outlet, and the LYS4000 can be field-converted to 240V. The LYS5000, LYS6000 and LYS7000 need a dedicated 240V, 50A GFCI-protected circuit installed by a licensed electrician. Read plug and play hot tub: 120V vs 240V, and see whether a 100 amp panel can run a hot tub if you are not sure your service is big enough.
- Delivery. Our pages list curbside (tailgate) delivery in the contiguous U.S. The carrier calls you to schedule the day, and the tub is set down at the curb or driveway. Plan help or equipment to move it to the pad, and check the path for gates, steps and tight turns.
- Inspection. Look the tub over when it arrives. The pages say shipping damage must be reported within 48 hours.
- The order itself. Liberty Spas hot tubs cannot be returned or exchanged once ordered, so confirm the size, power and access path first. If you want to talk it through, contact us before you order.
Local rules also apply. Permits, setbacks and fencing requirements for hot tubs vary by city and county, so ask your building department. We do not give local code advice.
Which model makes the pad plan easiest?
If your yard is small, the LYS4000 has the smallest footprint listed, at 84 by 60 inches, and the lightest filled weight at 2,050 lb. If you want to avoid new wiring, the LYS4000 and LYS4500 run on 120V. For larger groups, the LYS6000 and LYS7000 share the same 84 by 84 inch footprint, so one pad plan serves either, and our LYS6000 vs LYS7000 comparison covers the differences. Our best hot tub for home guide compares all the models, and how much a hot tub costs shows what the pad and power add to the budget. For the lifestyle trade-offs, read the downsides of owning a hot tub before you commit.
We have no owner reviews of these tubs on our store yet, so this guide rests on the manufacturer specs listed on our pages.
Frequently asked questions
Do I need a concrete slab for a hot tub?
Not by name, but you need a flat, level base that supports at least 150 lb per square foot and touches the whole bottom of the tub. Liberty Spas gives a 4 to 6 inch poured concrete pad as its example.
How thick should a concrete pad for a hot tub be?
Liberty Spas lists a 4 to 6 inch poured concrete pad as an example of a suitable base. Have the person who pours it confirm the pad meets at least 150 lb per square foot.
Can I put a hot tub on a deck?
Only if the deck is confirmed to carry the filled weight, which is 2,050 to 3,500 lb for the Liberty models we sell, plus people. Ask a deck builder or structural engineer to confirm it in writing.
How much does a filled hot tub weigh?
Our Liberty Spas pages list filled weights from 2,050 lb for the LYS4000 to 3,500 lb for the LYS7000, before the weight of the people in it.
Can I put a hot tub on gravel or pavers?
Our product pages name only a poured pad. Any other base has to be flat, level, at least 150 lb per square foot and in full contact with the bottom, and loose surfaces can settle over time.
Written by Logan McClure, founder of Restore Suite. Every guide is researched using peer-reviewed studies, recognized medical sources, and manufacturer specifications. This article is educational and is not medical advice. Learn about our editorial standards or contact our team.
