How to Level a Hot Tub on Uneven Concrete

Are you looking for a way to level a hot tub on uneven concrete? No one wants to halfway drown on one end and sit high-and-dry on the other.

Leveling a hot tub that is on uneven concrete can be done with simple shims if the slope is less than one inch. For steeper slopes, leveling will require more involved solutions such as custom-built pads of wood, sand or gravel, or even a new concrete pad. 

We’ve written how to level hot tub on gravel before. But if your hot tub is situated over an existing concrete surface, you may find that the concrete is somewhat unlevel to account for drainage or from poor construction. Whatever the case, you’ll want to read on for a few useful tips for leveling your hot tub over that uneven surface.

Use Plastic Shims

If your hot tub is out of level by an inch or less, consider using heavy-duty plastic shims to raise the low end. These shims are designed to be load-bearing and are an economical way to level your slightly off-kilter hot tub.

Be sure to check your hot tub manufacturer’s guidelines on using shims safely. You definitely don’t want to crack the tub by shimming it incorrectly. Also, some manufacturers do not recommend shims at all; doing so may void the warranty on your tub.

Ideally, start with an empty tub (less weight to deal with) and begin tapping in shims on the lowest side. Place shims at regular intervals across the low side, so they provide even support for the tub’s full weight.

Use Wooden Shims and a Platform

For slopes around an inch or so, you can build your own shims and a platform from pressure-treated lumber. After moving the tub aside, use pressure-treated 2×4 boards and a sheet of exterior grade plywood and:

1. Cut the 2x4s into wedge-shaped pieces based on your specific slope.
2. Insert them every foot or so across the low end of the tub base.
3. Cut and attach exterior grade plywood to the wood shims with screws.
4. Return the tub to its new, level platform.

For added stability, consider topping your platform with a spa pad like an E-Z pad. Specifically designed for use with hot tubs, these pads are relatively inexpensive and have a lifetime guarantee. 

They are made of heavy-duty plastic and can be picked up and moved if you ever need to relocate your hot tub. (For best results, your platform must be completely level.) E-Z pads can also be used by themselves on any level surface.

Purchase a Spa Leveler

A spa leveler can be used for a hot tub out of level by any measurement but is particularly appropriate when the uneven slope is greater than an inch. Several adjustable feet allow you to customize the spa leveler’s height based on the slope you’ve got to deal with.

If your hot tub is already in place, move it aside to put the spa leveler in the right place. You’ll need to know how far out of level your concrete pad is so that you can adjust the feet accordingly before reinstalling the hot tub on the new leveler.  

While a spa leveler is a pricey option, typically costing close to $600 plus shipping, it is constructed to last. The design allows water to drain away from underneath, so you don’t get wood rot or mildew under the tub.

An added benefit is its portability. If you ever need to move the hot tub, a spa leveler can be relocated and then releveled to the new spot’s contour by simply adjusting the feet again.

Build a Raised Pad

What can you do if your hot tub is off by more than an inch and you don’t want to spend this year’s Christmas budget on a spa leveler or new concrete pad? Consider building your own leveler. A raised pad constructed from wood and filled with sand or gravel provides a stable surface for your hot tub.

A custom-built raised pad will require a bit of carpentry knowledge and tools if you plan to do it yourself. If that thought makes you shudder, it should be simple enough to find a local handyman who can do the work for you at a reasonable cost.

How to Make a Custom-Built Pad

To get this nice, new, and level spa pad, you’re going to build a box frame out of lumber and fill it with gravel to create a level area for your hot tub. Custom-built means just that. For starters, you’ll need to calculate a few key things:

• Slope measurement: how out of level is your existing concrete pad?
• Amount of framing materials needed: 2×4 pressure-treated lumber and screws
• Amount of sand or gravel needed to fill the frame

Build a Box

Using the 2×4 lumber, build a box frame that is approximately one inch wider than your hot tub base. Each piece of wood should be ripped and tapered on the bottom so that when the entire box is built and placed on the uneven surface, the top boards are level all the way around.

• Pro Tip # 1: It’s critical that you use pressure-treated lumber to ensure that your new pad will stand up to the weather and any moisture around the hot tub.
• Pro Tip # 2: Drill several holes along the lowest board on the long (and lower) side; this will allow any water that splashes out of the tub or puddles after a rain to make its way down through the gravel or sand and drain out. 

Fill the Box with Gravel or Sand

Once you’ve built the box and fitted it to the sloping concrete, fill it with enough pea gravel or sand to come within an inch of the top; this gives you a sturdy base to put the hot tub on.

An alternative and optional filler for your custom-built frame box is cement. However, you should be sure that you’ll never want to move the hot tub before choosing this option since it’s a more permanent solution. 

Purchase bags of cement from a home improvement store and make your own concrete. Mix and pour into the frame and allow it to dry as directed before reinstalling your hot tub on the new pad. 

Paint or Stain the Wood

If you want your new hot tub pad to have a finished look, you can paint or stain it to match your tub base. It’s not a necessity but does add a professional, customized appearance. One benefit to paint or stain is that the wood will have protection from the weather, on top of its already pressure-treated nature.  

Pour a New Concrete Pad

If all else fails and you’re just not satisfied with other leveling options, consider having a new, level concrete pad poured. You can have it poured over the existing pad, providing extra support for the hot tub. 

Or, it’s the perfect chance to relocate your hot tub to that spot in the yard where you really wanted to put it anyway. Either way, pouring concrete is an expensive proposition, but you may find it worthwhile in the long run. Contact a local concrete mixing plant to determine costs in your area.

Final Thoughts 

Leveling a hot tub on uneven concrete is recommended to ensure the integrity of the tub itself and the users’ safety. There are several ways to accomplish this, depending on the tilt’s severity and your comfort level with DIY projects.

Whether you choose to shim it up, build a new pad, or purchase a prefab leveler, you’ll soon be enjoying a relaxing dip in your perfectly level hot tub.