There are many different ways to build swimming pools using various materials. There was a time when some pools were built using plywood as the frame to hold a liner, and we have actually done renovations on a couple of these type pools through our service division. But for our purposes, we should look at the three most common types of swimming pools available today. They are – concrete, vinyl liner and fiberglass swimming pools and we will discuss the pros and cons of each, the construction methods, and relative costs.
Concrete swimming pools are just that – pools constructed of concrete sprayed into a wire mesh formed into the shape of the swimming pool. You will hear concrete pools referred to as shotcrete, Gunite (which is actually a brand name) or just concrete, but the process is essentially the same. The design of the pool is laid out and the ground is excavated. Rebar (reinforcing steel bars) is then formed into the shape of the pool and tied together with steel wire. Then a concrete truck and an air compressor are joined together and the concrete is sprayed (shot) over the wire frame and troweled smooth. As the concrete hardens the pool takes shape, the floor of the pool is sprayed and it is all left to dry. Usually, the concrete is then covered with a coating of plaster (this will eventually become a maintenance issue) which smoothes the rough concrete making it more swimmer friendly. While there is much more to do, and a lot of time left to complete the process, eventually the pool is filled with water, connected to the pump and filter and you are ready to swim.
PROS – Concrete pools can be formed in any shape you can imagine, and are usually the pool of choice for large public swimming pools, hotel pools (although this is changing to fiberglass more often), big water park pools, and recently I saw one designed as a violin with LED lights running the length of the pool to represent strings. If a unique design is your plan, a concrete swimming pool is probably your best choice.
CONS – Concrete swimming pools require a lot of maintenance, with regular brushing and scrubbing as the porous plaster and concrete are a willing harbor for algae of all flavors. Eventually they will need to be acid washed to get them clean, and they will have to be replastered as cleaning will pit and crack the plaster. Also, compared with other types of construction, concrete swimming pools are expensive to build, take a long time to build, and can be rough on the feet and the bathing suit. Chemical balance is critical in a concrete pool, as incorrect levels of various chemicals – calcium for one – will quickly see the plaster erode from the walls, as the water draws calcium to stay balanced. Replastering is a very expensive proposition and often must be accompanied by sand blasting to remove the damaged material. Also, if a concrete pool moves with the ground, for whatever reason, it has very little flexibility, and will often crack. A cracked concrete pool is a serious issue, and depending where the cracks occur, might involve significant repair work.
Vinyl Liner swimming pools became very popular, and were another option to concrete pools, as the technology of plastics produced sheets of vinyl that could be printed with designs, and produced in varying thicknesses. While still very popular, especially in some of the Northern States, Vinyl Liner pool sales have fallen off significantly over the past ten years, as more homeowners choose fiberglass. The construction technique involves excavating the swimming pool but leaving a ledge (usually about three feet ) around the excavation. This ledge becomes the support for walls, often metal but more often polymer (plastic), which become the walls of the pool at the top. The bottom and remaining dirt walls of the pool are usually coated with a mixture of vermiculite and concrete. A vinyl liner is hung on the walls and allowed to drop into the excavation and provides a means of holding in the water in the exact shape of the excavation. Stairs are usually part of the wall system and the liner is cut to fit around them. Skimmers and returns and any other plumbing fixtures are also cut through the liner, and everything is hooked to the pump and filter.
PROS – vinyl liner pools can be built in most any design, but are usually offered in a set number of designs that are chosen to fit the manufacturers walls. These designs can be easily altered by adding or removing certain walls. Vinyl liner pools are the least expensive of the pool types, and are often a way families can a pool that suits their budget at the time.The liners can be printed in many beautiful patterns that mimic waves and waterline tiles – anything that you could think of, and some actually make the water sparkle in sunlight.
CONS – The largest of these is once again, maintenance. While not as bad as concrete, vinyl will give up calcium very quickly to the pool water. Also, algae is able to find a place to grab on in the vinyl. However, the very thing that makes liner pools attractive is the thing that makes them trouble – the liner. Liner replacement can cost $2500 to as much as $5000 and more, depending on size and related work. Liner warranties are another big problem. While you will hear numbers of 20 or 25 years warranty for a vinyl, that will only cover a failure of the seams – where the pieces of the vinyl are sewn together. Everything else is excluded.
FIBERGLASS swimming pools were first constructed in the 1950’s, although fiberglass (glass fibers) had been around since the early 1930’s. Although this is oversimplification, air is blown at molten glass and produces strands, or fibers of glass, which can then be woven into matting or spun into strands – fiberglass. The key to fiberglass is the resins that are used to harden the fibers into the tough resilient product we use today to make swimming pools. Sometimes the fiberglass strands are run through a special gun which “chops” the strands while mixing resins but the higher quality swimming pools use sheets of fiberglass and force the resins into the fibers by hand. The mats of fiberglass are then laid on top of each other forming a strong flexible swimming pool. This method requires everything to be done by hand, but produces a beautiful final product that will last a lifetime and more. You can see the process in photographs here at San Juan Pools and here is a great video of the same process – you might want to turn down the volume and just watch the process.
Without getting into mind numbing details, just be aware all fiberglass swimming pools are not constructed alike, and a little research into the company’s methods would be worthwhile. And, while fiberglass is (mostly) the same, the resins used are vitally different. The best fiberglass swimming pools, like San Juan Fiberglass Pools, will use pure Vinyl Ester (not marine grade) resins throughout the process – not just on the outside layers. It is more expensive to manufacture that way, but it ensures that your swimming pool will not have problems in a few years with fiberglass starting to come apart.
PROS – Fiberglass swimming pools are as close to maintenance free as you will find. Because the gelcoat (the side you walk on) is so smooth and non-porous, algae just has no way to hold on to the sides. Your stairs and seating areas will not hold dirt and any brushing required will take minutes not hours – in fact just passing a brush close to any dirt sitting on the fiberglass, will cause it to move with just the passing of the water. Fiberglass is tough and strong – almost indestructible, and if the ground moves because of rain water or just shifting, fiberglass will and move with the ground. Chemical needs are significantly reduced with fiberglass, again because it does not let algae take hold, and calcium needs for the water are not as serious as concrete pools. Fiberglass is also the best option for use with salt water pools. Fiberglass is impervious to salt water corrosion unlike concrete which can pit and streak like it does when salt is poured on the sidewalk to melt ice. Fiberglass pools have exploded in popularity over the past 15 years, and are the fastest growing segment of the residential swimming pool market as its strengths become more clear to homeowners.
CONS – Fiberglass swimming pools are always made somewhere else. Unless you live where one of the manufacturers has a facility – San Juan is in Lakeland Florida – your pool will have to be brought to you by truck. Because of bridges, overpasses, and State laws, the maximum height that can be transported is about 17 feet, so your fiberglass pool will have to be 17 feet wide or less. Most manufacturers have a set number of designs from which to choose, because each fiberglass pool has to have its own mold, and so choices are limited to the number of molds available to the manufacturer. San Juan pools currently offers 77 different designs, so there is something for everyone. Cost can also be an issue for potential fiberglass pool owners. While significantly less expensive than concrete pools, fiberglass pools are more expensive than vinyl liner pools – at first – but once you change out a couple of liners, the costs very quickly match each other, and you will never have to replace your fiberglass pool.