Swimming pools, like central air-conditioning systems, are no longer considered a luxury that only a privileged few can afford. New construction methods and materials have considerably lowered the cost of construction. Swimming pools can be installed either in-ground or aboveground. You will find them with various sizes and shapes that can fit into almost every budget. Because the shape of an in-ground pool can be freeform, the shapes available are limitless. On the other hand, the shape of aboveground pools is basically limited to circular, rectangular, or oval. There are three types of construction for the shell of an in-ground pool: concrete, vinyl lined with sidewall supports, and preformed fiberglass. These items as well as the pool’s associated equipment and accessories will be discussed below.
Concrete pools can be constructed using any of four methods: shotcrete, gunite, poured concrete, and concrete block. Both shotcrete and gunite are applied and sprayed from a hose that is directed behind, over, and above previously installed reinforcing rods (rebars). (See FIG. 18-1.) Shotcrete is premixed wet concrete, and gunite is a dry mix, which combines with water as it discharges from the hose. The spraying of the concrete mix allows complete freedom of size and shape because it can follow the contours of any excavated shape. Poured concrete and concrete block walls are more restrictive with regard to the shape of the pool. Whichever method is used to construct the shell, an interior finish must be applied to provide a waterproof surface.
The most common finish used on a concrete pool is plaster. It gives a smooth finish to the pool and also provides a nonskid walking surface. (See FIG. 18-2.) The projected life of a plaster finish is about 7 to 10 years depending on how well the pool and water quality has been maintained over the years. In many homes where the pool and the chemistry of the water have been diligently maintained, the plaster finish has lasted considerably longer.
Other finishes are paint, fiberglass coating, and ceramic tile. Tile is by far the most expensive; so most homeowners opt for a decorative ribbon of tile above the water line. The top edge of the pool shell is covered with coping, which prevents water from getting behind the shell. It can also serve as a hand-hold for swimmers and as a shove-off point into the water. The coping can be in the form of precast coping stones, flagstones, or brick, or it can even be the extension of a concrete deck over the edge of the pool shell.
Fig. 18-2. Plaster finish being applied to a concrete pool.
The advent of vinyl-lined pools brought the ownership of swimming pools to within the reach of many families. Construction of the pool shell consists of two phases: building of the perimeter frame or sidewalls and installing the liner. The most common sidewall panels are galvanized steel or aluminum. The frame must be structurally adequate to support the various forces exerted on the pool. After the sidewalls are bolted together, the bracing is installed. (See FIG. 18-3.) Then the area around the bracing is backfilled so that it is flush with the surrounding terrain. The sidewalls must have a smooth surface so as not to abrade the vinyl. They also don’t have to be waterproof since the vinyl lining is. Prior to installing the liner, the base must be prepared. The bottom of the liner generally rests on a 2- to 3-inch sand base, and the top is secured with a special coping. The life of a vinyl liner is affected by the sun’s ultraviolet light and the chemistry of the water. Manufacturers generally guarantee a liner against defective workmanship for 10 years. As vinyl pool liners age, the material becomes less supple and more prone to leaks from cracks or damage. It is possible to patch a small hole in a vinyl pool with a similar vinyl sheet material and a waterproof adhesive. Patching, if done correctly, can be effective, but once a liner has reached the age when several patches are needed, it is worth considering replacing the liner.
Fig. 18-3. Steel bracing for the shell of a vinyl-lined pool.
Aboveground pools are also vinyl lined. They are considered portable pools in that they can be dismantled and moved to a new location; however, many pools are partially or fully surrounded by a deck and are more permanent. The walls of the pool must be self-supporting and capable of withstanding the pressure being exerted on them by the water. The walls are usually galvanized steel, plastic, or aluminum and are 48 or 52 inches high. Because of the height of the walls, most municipalities do not require a safety fence surrounding the pool.
Preformed fiberglass pools
There are a number of advantages to a preformed fiberglass pool. The major advantage is its durability; the pool can flex and not get damaged. Also time is not lost in constructing the pool shell. After the site is excavated and prepared, the pool shell, which is brought to the site by truck, is lifted by a crane and placed into the excavation. (See FIG. 18-4.) Another advantage is the low maintenance. It is difficult for algae to cling to the sides of the pool because of its very smooth surface. As a result, the walls are very easy to clean. The main drawback of preformed pools is that they are limited in size and shape. However, once the installation of the pool is complete, you cannot readily tell the difference between it and an on-site constructed pool.