pool materials

Pool Materials: Gunite, Shotcrete, or Fiberglass?

In Construction Process by Swimming Pool Expert

Concrete or fiberglass? That is the question many future pool owners ask about pool materials. 

So did you know the two types of ingredients that shape your pool? Concrete is concrete, right? Or, how about a fiberglass pool? Many say that it is faster to build, is shaped-ready, and easy on the feet. So, why do more people prefer in-ground concrete pools?

It can be overwhelming, especially while researching options for buying a swimming pool. Professional pool builders toss around daily terms, technologies, methods, and processes daily, but it is not complicated.

Fundamentals on Concrete

Concrete is water, cement, sand, and coarse aggregate, a material made of small particles, usually small crushed stones or gravel.

The Difference Between Gunite and Shotcrete 

What difference has gunite and shotcrete? It is the way these types of concrete mix with water. Gunite is dry concrete and only mixes with water at the end of the nozzle spray onto a surface. Shotcrete, on the other hand, is wet entirely before it goes out of the hose.

Pool builders can use shotcrete or gunite in the construction process for the pool materials. The difference is when mixing with water. Shotcrete refers to wet concrete thoroughly mixed before it’s shot out of a hose. Gunite is a dry concrete that only mixes with water at the end of the nozzle when sprayed onto its final surface.

Most pool builders prefer the gunite process because it is easy to apply on surfaces with the right thickness.

Building a Pool with Gunite 

The gunite is a pre-mixed dry concrete that goes into a “hopper.” The compressed air pushes the material through a hose and out of a gunite nozzle where concrete mixes with water.

To manage a gunite machine requires a certified professional to do the job. The technician, also known as “nozzleman,” controls the amount of water mixed into the dry material. He manages the concrete’s consistency better when applying it to the walls and floor of the pool.

Gunite Advantages

  1. The gunite process allows applying concrete multiple times without risking a cold joint or point of weakness. The high-velocity sprayer delivers material from the gunite nozzle, ensuring that the concrete will bond.
  2. Contrary to applying shotcrete, gunite generally allows builders to take more time to complete the project correctly. It is less expensive, and there are fewer errors in the construction process. It may slow the process, but you will have a beautiful and well-built pool in the end. 

Gunite Disadvantages

  • The gunite process requires a highly skilled and licensed “nozzleman.” 
  • Improperly loaded dry mixtures can clog the hose pipe.
  • Gunite generates excess material or rebound. Unfortunately, the technician cannot use the rebound material.   

Building a Pool with Shotcrete 

Shotcrete is a wet mix that can also go through a hopper and nozzle. The difference with these pool materials is the process is that it requires high-pressure nozzles, so the concrete goes on as densely as possible. It also avoids creating pockets or bubbles of are in the structure. 

Shotcrete Advantage

 It forms a solid and consistent coat, which takes less time than the gunite process.

Shotcrete Disadvantages

  • Since shotcrete is pre-mixed, must apply it quickly in a single day. The nozzleman cannot pause. Whether sprayed or poured, any pre-mixed concrete won’t bond to a separate application of concrete that’s already dried.
  • Cracks can form if the pre-mixed concrete has a lot of water. Some may add water to the mix to keep the cement from hardening, but it compromises the strength of the material.
  • Shotcrete tends to cost more than gunite.

Building a Pool with Fiberglass 

For more than sixty years, the fiberglass pool was an alternative for the concrete version due partly to its strength and durability.   

After the stock market crash of 1987, fiberglass pools became very popular; and by the first decade of the millennium, fiberglass pool manufacturers became very creative. Many considered it the pool materials backyard tub at one time, but now it is an alternative for high-end backyards.

Between 2005 and 2015, fiberglass pools exploded from 6% to 17% of America’s inground pool market share, nearly tripling in size in only ten years.

Fiberglass Advantages

  • A fiberglass pool can last a while. 
  • It takes less time to install as it is prefabricated.

Fiberglass Disadvantages

  1. Poor installation – fiberglass pools arrive as a pre-manufactured shell. A pool installer must fill the space with sand and gravel while filling the pool with water to secure the proper support. Otherwise, everything can go wrong, like improper water circulation or collapse of one of the walls because the bracing was inaccurate. 
  2. Interference with water quality – fiberglass foundations have a gel coating that protects the carcass. If the alkaline levels in a pool are high, the chances are that it will need repairs sooner than expected. Even an improper calcium balance can be enough to deteriorate the protective gel.   
  3. Fiberglass pools are prefabricated – a customer will have to conform with the shapes available. 
  4. There is no customized pool unless they go “concrete.” The pool shell arrives in one piece, and if installed correctly, it can last a while.
  5. The fiberglass can warp – since the piece is prefabricated, a fiberglass pool can bend, bulge, and warp during the backfill process. Repairs can be costly, significantly if it breaches the integrity of one of your walls.
  6. Sun exposure can cause the pool materials topcoat to start pealing on the fiberglass – regardless of the many available designs, sun exposure can wear out. First, it starts to fade, and then the cracks and peels follow. Unless you go with a solid color; otherwise, make sure to have money aside for repairs.
  7. Spider cracks can be a big issue with some fiberglass pools – most thin cracks in the topcoat may result from poor manufacturing, tension during the installation, or problems with the shipping process. If the pool is under warranty, it will take longer to install. 

Pool Building Codes

Your property will need access to heavy equipment – HOA requirements and other building codes make it difficult for heavy equipment to access a residential property. 

  1. Remember, a fiberglass pool requires a crane to accommodate into the hole dug in your yard. If HOA does not allow having it around, you need to select a different type of oasis. 

Which type of pool will you select? 

Let the experts at Platinum Pools help you. Call us today at 281.870.1600 or visit our webpage for a free quote.