Above Ground Hot Tubs: How to Build Your Own (DIY Guide)

Last updated: September 2026

When most people hear “above ground hot tub”, they picture a shop-bought acrylic spa or an inflatable. Technically, that’s right: an above ground hot tub is any tub you step up and climb into, like a bath. But this website is about hot tubs you build yourself. So the real question is: can you build your own above ground hot tub?

Absolutely. I’d estimate around a third of the tubs my customers build are fully above ground, and a lot more are partly above and partly below. This guide covers when above ground makes sense, how to build one, and the things that catch people out, especially the structure, the plumbing and the heat loss.

In-ground vs above ground vs semi-sunken

Which you choose comes down to personal preference, your garden or backyard, and the views. I built mine in the ground, partly because I didn’t want to be “on display” to the neighbours. Sinking the tub and adding a small fence gave me the privacy I wanted. On the other hand, a raised tub can lift you up to a view you’d never see from ground level.

	Above ground	Semi-sunken	In-ground
Digging	Just the slab	Partial dig	Full dig, so lots of spoil
Access to plumbing	Easy	Part easy, part buried	Hard. I find it a challenge to service the buried parts on mine
Structure	Walls must resist all the water pressure	In between	Soil pressure and groundwater to deal with
Heat loss	Highest, as the walls are exposed to air	Medium	Loses heat into the ground, so insulate the floor and walls
Looks and privacy	Harder to landscape. You’re on show, but may get a view	A good balance	Blends in, and more private
Getting in	Steps or a deck needed	Sit and swing your legs in	Step down in

If you’re leaning towards in-ground, read my DIY in-ground hot tub build guide.

Design considerations

This is the fun part, where you get to put your dream down on paper.

• Location. Think about privacy, the view, sun and shelter from the wind. Keep it close enough to the house that you’ll use it in winter, and think about the routes for the electrics and pipework. A well-chosen spot makes the build easier too.
• Size. Work it out from how many people will use it and how often you entertain. There’s nothing worse, in my opinion, than banging feet and legs with everyone else. I like my space.
• Shape. Square and rectangular tubs are the easiest to build in block or ICF and the easiest to fit seats into. Round and octagonal tubs look great but take more work. Plan the seating and ergonomics with the shape, not after it.
• Getting in and out. A tall tub needs steps, a platform or a deck. See my guide to hot tub steps.
• Finish. This tends to be one of the more expensive bits, and there are lots of options. Inside, I’d always go for pool mosaic tiles. They look great, they’re made for the job, and they cope with the chemicals and temperature. Outside, render, stone or timber cladding all work.

Construction methods for an above ground hot tub

There are three main DIY-friendly ways to build the walls. Shotcrete and gunite are common in the trade, but they need specialist spraying equipment and experience, so they aren’t realistic for a DIY build. There’s a full comparison in Hot tub wall construction: what are the options?

1. Concrete block (CMU / cinder block)

Blocks are cheap, easy to get hold of and familiar. They’re manageable with basic masonry skills, and you can build almost any rectangular shape. For a hot tub, use hollow blocks with vertical rebar tied into starter bars from the slab, then fill the cores with concrete. See my cinder block hot tub guide.

2. Poured concrete in forms

You build temporary timber or metal formwork, fix the rebar, and pour the walls. It gives a strong, seamless wall with no joints, and it’s flexible on shape. But it needs careful planning, strong formwork (wet concrete pushes hard on the forms) and a good pour.

3. ICF (insulated concrete forms)

ICF is my favourite. It’s the method I’d use if I built mine again. The foam blocks interlock like Lego for adults, you add rebar, and then fill them with concrete. You get a strong reinforced wall with insulation built into both faces, which matters a lot on an above ground tub. The blocks are light, easy to cut, and easy to run plumbing through. See the best ICF blocks for a hot tub.

The structure: why above ground walls need extra care

This is the bit people underestimate. On an in-ground tub, the soil behind the walls helps to support them. On an above ground tub there’s nothing behind them at all, so every bit of water pressure pushes the walls outwards.

It’s more than you’d think. Water pressure increases with depth. For a 1m (40in) deep tub, the water pushes on each metre run of wall with a force of around 4.9kN, about half a tonne (roughly 350lb on every foot of wall). That’s before anyone sits in it, splashes about or leans on the edge. It’s all concentrated at the bottom, exactly where the wall meets the slab.

• Start with a proper slab. About 150mm (6in) of reinforced concrete on a compacted sub-base, with starter bars left sticking up where the walls go. My guide to building a hot tub base covers it step by step.
• Tie the walls to the slab with vertical rebar lapped onto the starter bars, and fill every core (block) or form (ICF) with concrete.
• Use the seats. Built-in seats act like buttresses along the bottom of the wall.
• Get an engineer’s view for anything unusually deep, long or tall, or where the tub is on a slope or part of a raised terrace.
• Waterproof the inside properly. Use render plus a pool-rated membrane, then flood test before you tile. See my waterproofing guide.

Plumbing considerations

Where to put the control room

Your control room houses the pumps, heater, filter and controls. Standard hot tub jet pumps are centrifugal pumps, and they aren’t self-priming. They need water to flow into them by gravity (a “flooded suction”). So the ideal spot is below the water line of the tub. With an above ground tub, that’s usually easy, as the equipment can sit at ground level next to it. Keep it close to cut pipe runs and friction, and make sure you can get to everything for servicing.

If the equipment has to sit above the water line, you’ll need a self-priming pump or a priming circuit. See Using a priming circuit above ground and Hot tub control room design considerations.

Jets: how many and where?

• How many: the jets I use need around 10 GPM each, so as a rule of thumb one jet pump runs up to about 16 jets. If you want more, add a second pump.
• Where: clusters of jets aimed at particular muscle groups give a focused, intense massage. A line of jets spreads the massage out and feels more gentle and relaxing. Think about who’ll use the tub and plan each seat.
• Hide the pipework. On an above ground tub, the pipes run in the wall or behind cladding, so plan the routes before you build the walls. It’s much easier to set pipes before you core-fill.

Heat loss: insulate every side

An in-ground tub is surrounded by soil. An above ground tub has cold air on all four walls, and wind makes it worse. That’s another reason I like ICF, which has insulation on both faces as standard. With block, add rigid insulation board behind the external cladding, insulate under the slab, and use a good cover. There’s more in DIY hot tub insulation.

Permissions and safety

• UK (England): The Planning Portal says you typically won’t need planning permission for a garden hot tub, unless you’re in a listed building or conservation area. The electrics must still meet Building Regulations. Watch any deck or platform around a raised tub, though. Decking is only permitted development if it’s no more than 30cm above the ground, among other conditions.
• USA: Many cities and counties want a permit for a built-in spa, and there are barrier rules to keep children out. Codes based on the ISPSC often exempt spas with a lockable safety cover meeting ASTM F1346. For example, Henrico County’s guide says barriers aren’t required for spas with a compliant lockable safety cover. Check your local rules in Do I need a permit for my hot tub?
• Electrics: use a dedicated, RCD- or GFCI-protected circuit installed by an electrician. See A guide to hot tub electrics.

Adding an above ground hot tub to an in-ground pool

An in-ground pool with a raised hot tub is a winning combination, often with the tub spilling over into the pool. A few things to get right:

• keep the two waters’ plumbing separate
• heat the tub independently
• balance the chemistry for each
• fit a valve so you can shut the spillover off

See Why pool and hot tub plumbing should remain separate and Adding a spillover hot tub.

What does it cost?

The cost is mainly driven by the size, the number of jets and the finish. Most of my customers build their own above ground tubs for less than $10K all-in. It goes up quickly if you pay contractors for parts of the build, or choose premium tiles and stone.

Common mistakes

• Building on a thin or unreinforced slab, or not tying the walls into it.
• Leaving block cores empty or unreinforced.
• Putting the pumps above the water line without a priming plan.
• Forgetting the insulation on exposed walls.
• No plan for steps, so getting in and out is awkward (and slippery).
• Running pipework before the wall and finish thicknesses are fixed.

Planning your own build?

All the designs in my shop work for both above ground and in-ground builds, and for either block or poured concrete construction. My DIY hot tub plans give you CAD drawings with every dimension, the plumbing layout, a full parts list and the video course.

Want something custom, like a raised tub on a slope or a tub next to a pool? Design it in the free Tub & Pool Designer Pro software, and I can turn it into architectural CAD and a 3D plumbing design. For parts, visit parts4tubs.co.uk in the UK or parts4tubs.com in the USA.

FAQs

Can I build an above ground hot tub myself?

Yes. Around a third of the tubs my customers build are above ground. You’ll need a reinforced slab, reinforced block or ICF walls, the plumbing and a pool-grade waterproofing and tile finish.

What’s the best material for an above ground DIY hot tub?

ICF is my favourite, because it’s strong, insulated and easy to plumb through. Reinforced, core-filled concrete block is a good, cheaper alternative. Shotcrete and gunite need specialist kit.

Where should the pump go on an above ground hot tub?

Below the water line, so the pump has a flooded suction. Hot tub jet pumps generally aren’t self-priming.

Is an above ground hot tub cheaper to run than an in-ground one?

Not automatically. The walls are exposed to air on every side, so it loses more heat unless you insulate them well. ICF and a good cover make the biggest difference.

Do I need planning permission for an above ground hot tub in the UK?

Usually not for the tub itself, unless it’s at a listed building or in a conservation area. A deck or platform more than 30cm off the ground may need permission, and the electrics must meet Building Regulations.

Got a question about your above ground build? Drop it in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi