🏗️ Quick Reference
- Material: Pneumatically applied concrete/mortar (cement, sand, water)
- Shell Construction: 1-2 days for the shoot; full project 6-12+ weeks
- Lifespan: 25+ years with proper maintenance
- Customization: Unlimited shapes and features
- Maintenance: Plaster resurfacing every 10-15 years
Gunite is a type of concrete that's pneumatically applied (sprayed) at high velocity to create pool shells. It's a mixture of cement, sand, and water that's applied using compressed air, allowing for complex shapes and custom designs that would be difficult with traditional poured concrete.
How Gunite Works | Gunite vs. Shotcrete | Advantages | Drawbacks | Maintenance | Common Issues | Spa Applications
How Gunite Works
The gunite process involves spraying dry cement and sand through a hose, with water added at the nozzle. This creates a dense, strong concrete that bonds well to rebar frameworks. The high-velocity application eliminates the need for forms and allows construction on vertical and overhead surfaces.
Gunite vs. Shotcrete
"Shotcrete" is the general term for sprayed concrete/mortar that includes both wet-mix and dry-mix processes. In the pool industry, people often say "gunite" to mean dry-mix shotcrete. Here's how the methods differ:
| Method | Mixing | Characteristics |
|---|---|---|
| Dry-Mix ("Gunite") | Dry mix with water added at nozzle | Complex shapes, easier to stop/start and clean up |
| Wet-Mix Shotcrete | Pre-mixed wet concrete | Faster application, often less rebound/waste |
Waste and rebound depend on crew skill and job conditions. Both methods create excellent pool shells, with choice often depending on contractor preference and project specifics.
Advantages of Gunite Pools
- Unlimited shapes: Custom curves, steps, benches, and features
- Durability: Properly constructed gunite lasts decades
- Strength: Excellent structural integrity when reinforced
- Finish options: Accepts plaster, tile, aggregate, and other finishes
- Repairability: Cracks and damage can be patched and refinished
Rebar, gunite mix, finishing materials, and construction tools. Professional-grade supplies for custom pool builds.
Potential Drawbacks
- Project timeline: Shell placement can be fast (1-2 days for the shoot), but full gunite pool builds commonly take 6-12+ weeks (sometimes longer). Fiberglass is usually quicker once underway
- Skill dependent: Quality varies significantly with contractor experience
- Porosity: Requires proper finishing to prevent algae growth in rough surfaces
- Cost: Generally more expensive than vinyl or fiberglass options
- Maintenance: Plaster resurfacing needed every 10-15 years
Maintenance Considerations
Gunite pools typically feature plaster finishes that require specific care:
Water Chemistry Requirements
- pH control: Target 7.2-7.6 (within standard pool range of 7.2-7.8) to prevent plaster etching or scaling
- Calcium hardness: Maintain 200-400 ppm to protect plaster surface
- Total alkalinity: 80-120 ppm for pH stability
Regular Care
- Brushing: Weekly brushing prevents algae buildup in textured areas
- Stain prevention: Address water balance issues promptly; consider sequestrants for metal staining
- Resurfacing: Plan for plaster replacement every 10-15 years
• Pool brushes designed for plaster surfaces
• pH and alkalinity adjustment chemicals
• Calcium hardness test kits and increasers
• Stain prevention and removal products
Common Issues
Plaster Problems
Etching from low pH, scaling from high pH/calcium, and staining from metals or organics. Proper water chemistry prevents most issues.
Structural Cracks
Settlement or poor construction can cause cracking. Small cracks are often cosmetic, but larger ones may indicate structural issues requiring professional assessment.
Surface Roughness
Over-troweling or poor finishing can create rough spots that harbor algae and feel uncomfortable. Professional refinishing corrects these issues.
For Spa Applications
Gunite works well for custom spas, especially when integrated with pools. The higher temperatures don't significantly affect the concrete, but plaster may need more frequent attention due to aggressive water chemistry and higher bather loads.