How Is a Gunite Pool Built? The Complete Gunite Process From Spray to Finish

Gunite (sprayed concrete) is the industry standard for custom pools. It's the method that allows unlimited customization, complex shapes, and durable structures that last 50+ years.

This guide explains how gunite pools are actually built, what makes the process complex, and why gunite is the premium option.

What Is Gunite?

Gunite is concrete applied using a high-pressure spray gun. The spray gun propels dry concrete and water onto the pool surface, where they mix and bond immediately, creating a hard shell.

Key difference from traditional concrete: Gunite is sprayed onto a framework, not poured into forms. This allows complex shapes and vertical surfaces.

The Gunite Pool Construction Process

Step 1: Prepare the Basin (Done Before Gunite)

• Excavate and grade pool basin
• Install main drain (usually center of pool floor)
• Install utility lines (if needed)
• Create framework or rebar skeleton if required for complex shapes

Step 2: Install Structural Components

Rebar placement (if needed): - Steel reinforcement bars placed throughout basin - Held in place with wire or chairs - Prevents cracking as pool cures - Not always required in residential pools but recommended for large pools

Why: Rebar adds structural strength, especially on sloped sides or deep pools.

Step 3: The Actual Gunite Spray (2–3 days)

The spraying process:

• Gunite crew arrives with spray equipment and concrete pump truck
• Dry concrete mix is loaded into spray gun hopper
• Water is added through the spray nozzle (concrete and water mix as material exits)
• Nozzle operator sprays concrete onto pool basin in overlapping passes
• Material builds up in layers (typically 4–6 inches thick)
• As concrete cures, subsequent layers bond to previous layers

What you'll see: - Large spray equipment and hoses - Loud noise from compressors - Dust and overspray - Concrete being sprayed onto pool surfaces - Nozzle operator constantly adjusting angle and pressure - Material bouncing off surfaces (overspray) caught in containment - Pool surfaces becoming white/gray as concrete covers them

Timeline: - Small pool (under 500 sq ft): 1–2 days - Medium pool (500–800 sq ft): 2–3 days - Large pool (800+ sq ft): 3–4 days

Step 4: Trim and Shape (1–2 days)

After initial spray, crew: - Trims excess material - Smooths surfaces with tools - Creates clean edges - Adjusts for any high/low spots

Step 5: Initial Cure (7–10 days)

The gunite must cure (harden) before next steps:

• Cannot disturb or pressure wash for 7 days
• Full strength isn't reached for 28 days, but 7–10 days is enough for construction to proceed
• Temperature affects cure time (cold slows it; heat speeds it)
• Rain during cure can damage surface (crew covers if rain threatened)

What you'll see: Nothing much. Pool sits and cures. Can't go in pool during this time.

Step 6: Acid Wash (Optional, 2–3 days)

Some builders acid wash the gunite before finish to: - Clean surface - Remove excess cement dust - Improve adhesion of finish coat - Improve aesthetics

Note: Not always done; depends on builder preference and finish type.

Step 7: Apply Interior Finish (2–4 weeks)

After gunite cures, interior finish is applied:

• Plaster: Smooth coating, 1/8" thick
• Aggregate: Crushed stone/marble embedded in plaster
• Pebble: Natural pebbles embedded, very durable

This finish is what you see and touch—not the gunite itself.

Why Gunite Is Superior

Customization

You can build any shape: - Irregular freeforms - Beach entries - Sloped floors - Attached spas - Integrated water features - Any design you imagine

Durability

50–100 year lifespan with proper maintenance. More durable than vinyl or fiberglass.

Strength

Can support structures (water features, attached elements) built into pool design.

Maintenance-Friendly

Repairs are straightforward. Small cracks can be patched. Finish can be renewed without rebuilding structure.

Quality Factors in Gunite Application

The Spray Operator's Skill

Gunite quality depends heavily on operator experience:

Good operator: - Even coverage - Proper consolidation - Smooth finish - Correct thickness - Clean edges

Poor operator: - Uneven coverage - Inadequate consolidation - Rough finish - Thin/thick spots - Rough edges

Why it matters: Operator skill directly affects durability and final appearance.

Concrete Mix

Quality concrete mix affects durability:

Good mix: - Proper water/cement ratio - Right aggregate gradation - Additives for strength/workability

Poor mix: - Too much water (weakens concrete) - Incorrect aggregate - Causes cracking and early failure

Application Technique

Proper technique: - Perpendicular spray angle (90 degrees to surface) - Correct speed and distance - Layered buildup (not one thick coat) - Proper consolidation (material bonds well)

Poor technique: - Angled spray - Inconsistent pressure - Single thick coat - Inadequate consolidation

Common Gunite Problems (and Prevention)

Cracking

Cause: Too much water in mix, inadequate consolidation, rapid drying

Prevention: Quality mix, skilled application, proper curing, misting during cure

Spalling (Surface Deterioration)

Cause: Freeze-thaw cycles, poor finish adhesion, water intrusion

Prevention: Good seal/finish, proper drainage, maintenance

Thin Spots

Cause: Operator rushing, inadequate material buildup

Prevention: Quality operator, proper oversight

Frequently Asked Questions

Is gunite better than fiberglass or vinyl?

For custom pools: yes. Gunite allows unlimited shapes, integrations, and customization. Fiberglass and vinyl are more limited.

For simplicity and speed: Fiberglass is faster and lower maintenance. But it's less customizable.

How thick is a typical gunite pool shell?

Standard: 4–6 inches thick. This is sufficient for residential pools.

Why not thicker? More thickness doesn't meaningfully improve strength. 4–6 inches is engineering standard.

Can gunite pools crack?

Yes, minor cracking is normal. Most cracks are hairline and cosmetic. Larger cracks (over 1/8") should be sealed to prevent water intrusion.

Proper finish and maintenance prevent most problems.

How long before you can put water in after gunite?

7–10 days minimum. Gunite is hard enough, but interior finish isn't applied yet. Water can go in after interior finish is applied and cured (typically 2–3 weeks after gunite spray).