Four Different Types of In-Ground Pools and How to Choose One

Concrete

Best for: Permanent in-ground pools

Made of steel-reinforced concrete that forms a shell, concrete and plaster are the most common in-ground pool-building materials and were the first ones used when residential pools became popular. The reason: Concrete is durable and porous, which allows the plaster-coated shell to hold water, provide stability, and be replastered when needed, adding to its longevity and durability.

Even though concrete has a higher up-front cost (as opposed to vinyl, for instance), it is considered the most cost-friendly option long-term as it can be maintained for years and likely will never have to be replaced if properly cared for.

Here's how it works: after a hole has been excavated in a yard, the sides and bottom of the hole are lined or framed with rebar (steel rods). These can be sculpted into nearly any shape conceivable (from rectangles and hearts to guitars), along with adding steps, ramps, and other features.

After the rebar is positioned, the pool shell is made by spraying a finish using shotcrete or gunite, a combination of sand, concrete, and water that's sprayed onto a surface using a hose. Once the concrete material is cured, it's topped with plaster (a combination of cement and marble dust), which may also include colored quartz for aesthetics.

Plaster is what makes the pool actually waterproof and is an essential step in the process. Concrete pools also act as a base for various other popular pool finishes, such as tile or stone.

This method helps a contractor in deciding the size and shape of a concrete pool. In most cases, a pool with modern curves should not cost any more than the same-size pool with a more traditional, angular shape.

Once the concrete base of the pool is established and set (in steps similar to the above), the pool is coated with a thinset mortar upon which tile or stone can be set. The tile should be set for a minimum of 24 hours before finishing with a grout that has been polymer-fortified to stand up to constant moisture and pool chemicals.

Typically these finishes last between 8 to 12 years and can be difficult to repair or replace, often necessitating the draining of the pool and a professional fix for even small chips or missing titles.

Fiberglass

Best for: Low-maintenance in-ground pools

An in-ground swimming pool made of fiberglass will be sold as a large one-piece shell that arrives at your home by truck and then is positioned in the excavated hole with the help of a crane. A fiberglass pool has high up-front costs, but it has lower maintenance costs over time. It has limitations on size and comes in pre-fabricated molds.

Unlike concrete pools, fiberglass pools are ready-made, making it difficult to request a customized design. Most fiberglass manufacturers offer many models and sizes to choose from, and things like steps, spas, and benches are usually pre-formed.

Fiberglass makes the pool-building process quick and easy. The smooth interior surface is slick, making it tough for algae to cling to. After 10 to 15 years of exposure to the sun and chemicals, the fiberglass gel coating deteriorates. Recoating the gel is not easy because the new coating does not stick easily to the older one and is a tedious process.

A fiberglass pool is however not prone to growing algae, and over 10 years, the lifetime costs to maintain this type of pool are the least costly. It should rarely need acid washing or deep refinishing (except for the possibility of topical recoating) unless it has been uncovered or in a very sunny environment for an extended period of time.

Vinyl

Best for: Least expensive in-ground pools

Pools that are lined with vinyl are built with metal or plastic frames above or below ground or set into the excavated hole. Prefab supporting walls or panels made of plastic, steel, or aluminum are joined to the frame, making a form that is then lined with heavy vinyl to create the pool shell.

The bottom of a vinyl liner sits on a bed of sand or other material, while the top is held down by the coping, which creates a finished edge and also acts as a border for the pool deck. Vinyl liner pools are the least expensive in-ground swimming pools and can be built in any size and shape.

Like other finishes, vinyl deteriorates over time with exposure to the elements as well as pool chemicals. Some liners come equipped with fungus and UV inhibitors, which can extend the life of a vinyl liner from 10 years to about 18 years. Depending on your location, a vinyl pool can be the least expensive option, running approximately $20,000 to $50,000.

Gunite

A gunite pool is very similar to a concrete or shotcrete pool except for one part. While shotcrete is shot onto a steel structure that's already mixed, gunite is shot out dry with a water source at the nozzle to add water at the end, making gunite a dry mix while shotcrete is a wet mix.

To construct a gunite pool, the process is similar to a concrete pool. First, a hole must be excavated, and then steel is placed at the walls for re-enforcement. Then when it is time for the gunite, the dry mix is loaded into a hopper which then pumps the still dry gunite mix through a hose to a nozzleman.

The nozzleman will be on the end of the hose doing a few very important jobs. The nozzleman controls the amount of water introduced to the mix as it gets shot onto the reinforcing steel. Simultaneously, it is also responsible for aiming the nozzle to create an equally filled surface. After, the gunite is allowed to wire for 28 days and is now ready for any finish of your choice.