If you want something cleaner and more reliable than a rock-and-mud swimming hole in your backyard—and more permanent than an above-ground pool—there are four main types of in-ground pools you can consider. While wood is a possibility, the cost of building one that would not deteriorate in a few years narrows the choices down to the most popular and efficient. Keep in mind that there are also variations on these main types, allowing you more options.
Here's what you need to know about the four types of in-ground pools.
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Concrete With Plaster or Aggregate Finishes
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. This is considered the most cost-friendly option as well, 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.
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.
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Concrete and Tile or Stone
Concrete pools also act as a base for various other popular pool finishes, such as tile or stone. 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 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.
Opting for tile or stone for your pool is a purely aesthetic choice and doesn't really have much of an obvious benefit to the longevity of your pool. 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.
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A 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. 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. However, fiberglass can be more costly. After 10 to 15 years of exposure to the sun and chemicals, the fiberglass deteriorates and recoating it is not easy because the new coating does not stick easily to the older one.
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Pools that are lined with vinyl are built with metal or plastic frames above 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 form 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.
Like other materials, 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.
What type of in-ground pool lasts the longest?
Concrete pools tend to be the strongest, most durable of all the in-ground swimming pools. They can't oxidize or corrode and get stronger as time passes.
What type of pool is the easiest to maintain?
A fiberglass pool is not prone to growing algae, and over 10 years, the costs to maintain this type of pool are the least costly. It never needs acid washing, refinishing, or liner replacement and only needs filtering once per day.
What type of in-ground pool is the cheapest to build?
Vinyl liner pools are the least expensive in-ground swimming pools and can be built in any size and shape. A fiberglass pool has the highest upfront cost, but it has the lowest maintenance cost over time. It has limitations on size and comes in pre-fabricated molds.