What Is Gunite in Pool Construction?

Gunite is concrete sprayed at high speed onto a steel cage to form the shell of an inground pool.

Pool Builders Directory · October 18, 2026

Gunite is a mix of cement and sand that a crew sprays through a hose onto a steel frame to form the shell of an inground pool. Water is added at the nozzle, so the mix is applied "dry" and gets wet only at the last moment. Once it hardens, it is a solid concrete shell that is later finished with plaster, tile, or another surface.

If a builder says "concrete pool," they usually mean gunite or its close cousin, shotcrete. This guide explains the difference, walks through the build, and lists the questions worth asking before you sign.

Gunite vs. shotcrete

Both are concrete that is sprayed with pressure. The difference is when water joins the mix.

• Gunite is a dry mix. The crew feeds dry cement and sand through the hose, and water is added at the nozzle. The nozzle operator controls the water.
• Shotcrete is a wet mix. It arrives already mixed, like a ready-mix truck load, and is pumped through the hose.

Many builders use the words as if they mean the same thing. Both make a strong shell when installed well. Ask which method your builder uses and why. A good builder will give you a plain answer.

How a gunite pool is built

The order of work is similar from one builder to the next. Details vary by site, soil, and local rules.

1. Design and permits. You approve the shape, depth, and features. Your builder or the city handles permits, depending on your area.
2. Excavation. A crew digs the hole to the planned shape. Soil type and groundwater affect the work and the plan.
3. Steel and plumbing. Workers tie a cage of steel reinforcing bars (rebar) to the shape of the pool. Main drains and pipes go in around it. Many places require an inspection at this stage, before any concrete goes on.
4. Spraying the shell. The crew sprays the mix over the steel and builds up the floor, walls, steps, and benches. They trim and shape it by hand as it sets.
5. Curing. The shell hardens and gains strength. More on this below.
6. Tile and coping. Waterline tile and the cap along the pool edge (coping) are installed.
7. Decking and equipment. Pumps, filters, and the deck are finished.
8. Interior finish. The inside surface goes on, most often plaster. Other options include pebble-style finishes and tile.
9. Fill and start-up. The pool is filled and the water chemistry is set up and watched closely at first.

Why the finish matters

The gunite shell is structural, but it is not the surface you swim against. It is rough and porous. The interior finish seals it and gives the pool its look and feel. The finish wears out over time and is replaced or redone several times over the life of the pool. The shell itself is meant to last far longer.

Plaster is smooth and common. Pebble-style finishes are tougher and feel more textured. Tile is the most durable and usually costs the most. Ask your builder to show you real examples of each, and ask how each one feels under bare feet.

How long does gunite take to cure?

Concrete does not dry like paint. It hardens through a chemical reaction with water, and it keeps gaining strength for weeks. A common benchmark in the concrete industry is 28 days to reach its design strength.

Builders often keep the new shell damp for the first days, usually by spraying it with water, so it does not dry too fast. Fast drying can cause cracks. Your builder sets the timing for the next steps, so follow the schedule you are given. Do not push a builder to rush the interior finish. Weather, season, and the mix design all play a part.

The whole project, from digging to a swimmable pool, commonly takes several weeks to a few months. Permits, weather, and inspections often cause the longest waits.

Pros of gunite

• Custom shapes. The crew sprays the concrete onto a steel frame, so nearly any shape, depth, and feature is possible. This includes free-form pools, vanishing edges, and built-in steps and seats.
• Strength. A steel-reinforced concrete shell is strong when it is built well.
• Finish choices. You can choose from several interior finishes and change them later.
• Size flexibility. Size is not limited by what a factory can ship on a truck.

Cons of gunite

• Longer build. Fiberglass shells arrive pre-made. Gunite is built on site, so it usually takes longer.
• Higher upkeep. The porous finish can grow algae more easily than a smooth surface. Plaster needs careful water chemistry, and it will need to be resurfaced at some point.
• Cracks can happen. Concrete can crack from settling, shifting soil, poor curing, or poor steel placement. Hairline cracks are common and often cosmetic. Large or growing cracks, or cracks that leak, need a pro.
• Cost. Gunite pools typically cost more than vinyl liner pools and often more than fiberglass, depending on size, finish, and site. Get written quotes from several builders to see real numbers for your yard.

Common mistakes to avoid

• Comparing quotes that do not match. Check that each quote lists the same size, finish, tile, coping, equipment, and deck. A low price often leaves items out.
• Skipping the soil question. Ask whether your builder has tested or reviewed the soil and groundwater at your site, and how they plan for them.
• Rushing the cure. A pool that is plastered or filled too soon can have problems later.
• Ignoring the start-up plan. New plaster needs careful brushing and water testing in the first weeks. Ask for the start-up steps in writing.

Questions to ask a builder

• Do you use gunite or shotcrete, and why?
• Who does the spraying, and how long have they done this work?
• What steel spacing and size do you use? Will the city inspect it before spraying?
• How do you cure the shell, and how long before the finish goes on?
• What does your warranty cover for the shell, the finish, and the equipment? Get it in writing.
• Can I visit a pool you built several years ago?

You are hiring a crew as much as a material. The skill of the people spraying, trimming, and finishing the shell matters as much as the word "gunite" on the contract.

When to call a pro

Plan to use a licensed pool builder for new construction. Spraying gunite takes trained crews and heavy equipment. For an existing pool, call a pro if you see wide or growing cracks, a steady drop in water level, hollow-sounding plaster, or rust stains from the steel. These can be signs of problems that get worse with time.