How to Install Gunite Jet Bodies in a DIY Hot Tub (Step by Step)

Last updated: September 2026

Gunite jet bodies can seem complicated. When I was planning my own tub, I couldn’t find a single diagram or video that properly explained how they went together, and they’re not cheap, so ordering them felt like a leap of faith. In this post I’ll de-mystify them: what each part does, how to set them into your wall so they finish flush with the tiles, and the mistakes I made along the way.

What are gunite jet bodies?

If you’ve seen the YouTube videos of shotcrete or gunite being sprayed onto a steel framework to form a pool, then skimmed smooth by highly skilled crews, you’ve seen these parts before. That isn’t the kind of hot tub most of us can build in our own back gardens or backyards. But if you’re building a concrete, cinder block or brick hot tub, or using ICF, your jets still need to get through the wall. Gunite jet bodies are exactly how that happens. (If you’re weighing up wall systems, see 2 alternatives to gunite or shotcrete.)

That’s my build above. You can see two sets of pipe connecting to the gunite jet bodies, and the bodies taking the flow through holes in the blockwork and into the tub.

How do gunite jet bodies work?

The two pipe runs carry water (the larger 2in pipe at the bottom) and air (the smaller 1.5in pipe on top) into each body. The air and water mix in the jet body, and that mixture comes out through the jet. You can really feel the difference: run the pump on full without the blower and the jets are good; switch the blower on and they feel far more powerful. The pump’s flow is still doing the work, but the air adds volume and that bubbly punch.

The water and air lines are separate, but when the blower is off, water will get into the air pipework. That’s normal, as long as you protect the blower. Always fit a check valve (non-return valve) and a Hartford loop, where the air line rises above the waterline before it drops to the jets. A blower full of water will trip your supply and kill the blower. There’s more in my top tip for installing an air blower.

You don’t have to use a blower at all. With a venturi setup, the moving water draws air in through an air line that’s open to the atmosphere. I’ve covered the pros and cons in Do I need an air blower or can I use venturi? and how to do it in How to use a venturi system instead of a blower on a block hot tub build.

What are the parts of a gunite jet body?

The gunite jets I used have six parts.

Part	What it does
1. 2.5in rigid pipe	The sleeve that runs from the body, through the wall, to your finished surface
2. Gunite jet body	The tee behind the wall that takes the water and air connections
3. End cap (plaster niche)	Glued onto the front of the 2.5in pipe and set flush with your tiles
4. 1in threaded ring	Glued to the inner pipe so it screws into the back of the body
5. 1in rigid inner pipe	Runs inside the 2.5in sleeve from the body to the jet holder
6. Jet nozzle holder (wall fitting)	Glued to the front of the inner pipe; the jet itself pushes or screws into this

Different brands name these parts slightly differently and have their own dimensions. Waterway, for example, calls part 3 a “plaster niche” and part 6 a “wallfitting”. Always read the instructions for the exact jets you’ve bought. The measurements below are from mine.

Before you start: planning and holes

Work out your finished surface first

Everything about a gunite jet is set from the finished face of the tub, not the blockwork. On my build I allowed the end caps to stand about 10mm proud of the block, for a thin coat of render and an 8mm tile. With a proper waterproofing membrane and a flexible pool-grade adhesive bed, most builds need more than that. Add up your actual layers (render, membrane, adhesive, tile) before you fix a single body. There’s more on those layers in Waterproofing, grout and tile adhesive and Hot tub tiles.

Jet heights and spacing

Set out your jets on the wall first. I placed mine to hit the middle of my back when seated, in an even line around the tub. Check that each body clears the seat and that there’s room for the pipes behind. There’s more on layouts in DIY hot tub jets and how many your pump can run in How to correctly size a hot tub pump.

Cutting the holes

The hole has to take the 2.5in pipe, which is 73mm (2.875in) on the outside, so a hole marked “2.5in” won’t be big enough. The front of the hole also needs to be slightly bigger again for the end cap (see below).

• Block walls: I managed with a good hammer drill and a chisel, but hiring a core drill makes it far easier and neater.
• ICF walls: cut the foam with a hole saw before the pour, and fix the bodies and sleeves so they can’t move when the concrete goes in. If I built again, I’d use ICF. See the best ICF blocks for building a hot tub.
• Keep every hole square to the wall and level. I didn’t quite manage this on a couple of mine, so those jets don’t sit perfectly flush. Nobody else notices, but I know.

Decision time: pipes first or bodies first?

Before you assemble the jet bodies, decide whether to connect the external air and water pipes first, or fit the bodies in the wall and then pipe them. This really depends on your site and how close the jets are to each other. The closer they are, the harder it is to get even “flexible” pipe into the sockets on each side of the bodies, as it can be very tight.

I found it easier to assemble the external pipework with the jet bodies first, then push the whole lot through the holes. The choice is yours, but dry-fit everything before you reach for the cement. Here’s how to make the perfect PVC solvent weld joint.

Step 1: Fit the 2.5in pipe and set the end cap

Solvent-weld the 2.5in rigid pipe (part 1) into the jet body (part 2), applying cement to the inside of the body socket before you push the pipe in.

Now push the body through the hole in your wall. The end cap (part 3) is slightly wider than the 2.5in pipe, so you may need to chisel the front of the hole out a little to fit it.

Next, mark the length of pipe for cutting. The end cap doesn’t slide all the way onto the pipe, so allow for that when you measure.

On mine, the end cap sits about 30mm (1.2in) onto the end of the pipe (marked “A”), so the first 30mm of the hole needs to be about 4mm wider to take it snugly. It then protrudes about 25mm (1in) beyond the end of the pipe (marked “B”). The goal is for the face of the end cap to sit flush with your finished tiles.

When the tiles go on, the fitting should finish flush, like this:

Step 2: Pressure test, then seal the bodies in

Before anything gets buried, pressure test the plumbing. Waterway’s own Power Gunite Jet instructions have you glue a temporary cap on the 2.5in pipe for exactly this reason. Finding a leaking joint now costs you a fitting. Finding it behind tiles is a very bad weekend. See How to detect and fix a hot tub leak.

Then seal around each body so it’s watertight, front and back, unless it’s cast into concrete (as in ICF or poured walls). You can use an epoxy or, as I did, a waterproofed concrete mix to pack all the gaps. On mine, the joints were later finished with waterproof grout too.

Don’t forget the waterproofing: each jet is a hole through your waterproofing, so it’s one of the most likely places for a slow leak. Take your render and membrane neatly up to and around every fitting, following the membrane maker’s detail for pipe penetrations, and include them in your flood test before you tile.

Step 3: Assemble the inner pipe and jet holder

First, solvent-weld the threaded ring (part 4) onto the 1in inner pipe (part 5).

This lets you screw the inner pipe into the back of the jet body. The picture below shows how it works without the 2.5in pipe fitted, just so you can see it. By this stage, your bodies should be well and truly fixed into the walls.

With the bodies in the wall and the inner pipes screwed in, you should be looking at something like this:

Step 4: Mark and cut the inner pipe

Take a straight edge across the finished face and mark the flush point on each inner pipe (marked “D” below). Don’t cut it there!

The jet nozzle holder (part 6) is longer than the pipe it glues onto, so you need to measure back from your flush mark to find the real cutting point (marked “E”). I’d cut a few millimetres short of E, because the fittings never go 100% home. For reference, Waterway’s Power Gunite Jet instructions say to cut the 1in pipe 5in back from the flush mark before gluing on the wall fitting. Check the figure for your own jets, as it varies between models.

Unscrew the inner pipe, cut it just short of your mark at E, then solvent-weld the jet nozzle holder (part 6) onto the cut end.

Step 5: Screw it home and fit the jets

Screw the inner pipe back into the body. The nozzle holder should now sit flush with your finished surface. Some makers recommend a wrap of PTFE tape on the thread for a snug fit.

All that’s left is to push in (or screw in) your jet internals. The finished jets on my tub look like this:

One important point: you can only swap jet internals within the same manufacturer and series. Pick your brand before you buy the bodies.

UK and USA: what’s available

The jets I used were Waterway, an American brand, even though I built in the UK. Other makers use different sizes. For example, the HydroAir (Balboa) 1.5in gunite venturi tee sold in the UK takes a 1.5in water pipe and a 1/2in air pipe. Whatever you choose, keep every body, internal and pipe size in the same system, and don’t mix imperial and metric pipe. There’s more on that in DIY hot tub plumbing.

Common gunite jet mistakes

• Forgetting the thickness of render, membrane, adhesive and tile.
• Bodies not square to the wall, so the jets sit at an angle.
• Holes cut to the pipe’s nominal size instead of its real outside diameter.
• Cutting the inner pipe at the flush mark instead of allowing for the nozzle holder.
• Setting the end cap too far back, so air escapes behind the jet instead of through it (I did this on a couple).
• No pressure test before sealing in.
• No check valve or Hartford loop on the blower line.
• Mixing jet brands or series.

Planning your own build?

My DIY hot tub plans show where every jet body goes, the plumbing to each one and a full parts list, and the video course walks you through fitting them.

If you’re designing something custom, the Tub & Pool Designer Pro plumbing design service will lay out your jets and pipework for you. For jets, pumps and blowers, head to parts4tubs.co.uk in the UK or parts4tubs.com in the USA.

FAQs

Can I use gunite jets in a block or ICF hot tub?

Yes. That’s exactly what I did. They’re designed to be cast into concrete, but they work through block, ICF and poured walls as long as they’re sealed properly.

What size hole do I need for a gunite jet body?

Big enough for the 2.5in pipe, which is 73mm (2.875in) on the outside, plus a slightly wider section at the front for the end cap. Check your jet maker’s instructions.

Do gunite jets need an air blower?

No. You can run them with a blower or as venturi jets that draw in air from an open air line. A blower gives a stronger, bubblier feel.

How far should the jets stick out from the blockwork?

Far enough to finish flush with your tiles. Add up render, membrane, adhesive and tile thickness. On my build, that was about 10mm, but most modern build-ups need more.

Can I mix jets from different brands?

No. Jet internals only interchange within the same manufacturer and series.

Got a question about fitting your jets? Drop it in the comments below. I read them all.

Cheers,
Andi

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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