Concrete vs. Fiberglass Pools:
What’s the Best Choice for Texans?
Although the decision to install an in-ground swimming pool may be a no-brainer in most areas of Texas, the details of that are anything but cut and dried. Gunite seems to be the favored, “go-to, tried and true” pool material for Texans, but when you take a closer look at fiberglass composite, you may decide that “just because it’s always been done that way” doesn’t make Gunite the best choice.
By weighing and comparing all the facts about costs, installation, durability and features for both Gunite and fiberglass pools, Texas homeowners can make logical and informed decisions that are right for their families. Let’s start with an overview of these two pool options.
The Basics about Concrete pools
Concrete, often referred to as Gunite, as a pool building material has been a popular choice in Texas until recent years. Gunite is a mixture of sand and concrete that is sprayed onto surfaces at high velocity. It is helpful to understand the steps for installing a concrete/Gunite pool as part of the decision-making process:
1. The installation process starts by excavating the pool area of the yard per the pool design, allowing an extra 9 to 12 inches in all directions for surfacing the bottom of the pool and to allow a lip around the perimeter for a work area.
2. Plumbing should next be installed, including a drain at the bottom of the pool and the correct layout to ensure water flow throughout the pool. All plumbing must be hydrostatically pressure tested for leaks by a plumber before continuing.
3. Next, a steel rebar grid is installed around the entire inside of the pool, defining any steps, benches, spas and other features. The rebar frame provides stability for the concrete.
4. Now it’s time to build the walls and floor with Gunite. The Gunite is a dry mixture of sand and concrete that is mixed in a cement mixer and then combined with water as it is sprayed in such a way as to encapsulate the rebar frame. This process will take the better part of a day. Although 6 to 8 inches is typical, Gunite thickness can vary based on size, shape, and depth of the pool, and workers will smooth and shape it to achieve smooth walls, seats, steps, and floor.
5. Gunite needs to cure for a period of time. Depending on the installer, this will take up to a month, during which time the Gunite will need to be hosed down daily with water in order to assist the curing process.
6. After the Gunite has cured, decking, plumbing, pool equipment, and decorative touches can be worked on. Features such as a 6-inch tiled band are set, and the pool’s decorative edge, known as coping, is then added, eventually blending with the pool’s finished interior to give it a seamless, polished look.
7. Adding plaster to the final major step. Most often, this involves using a plaster with either a traditional white plaster coat or a finish containing various types/colors of aggregate. The plaster waterproofs the pool and helps create a smoother surface than the course concrete.
Note: From excavation through curing to finishing touches, Gunite pool construction can take anywhere from 75 to 90 days, depending on local specifications and the pool installer’s standards. And that’s not accounting for any weather delays that happen in the area.
The Basics about Fiberglass pools
Fiberglass is a type of sturdy, resin mix that is reinforced with composite glass fibers. It is an ideal material for swimming pools because it is smooth, non-porous, strong and flexible. Fiberglass Composite pools are precision-made by applying resin, fiberglass and other composite strengtheners in layers to a prefabricated mold. As an example, one of the leading manufacturers of fiberglass swimming pools, creates its pools using a 10-stage process that layers fiberglass multiple times with Vinyl Ester Resin (for durability and strength), a sturdy core of ceramic, carbon fibers or more fiberglass (for added strength), and embedded vertical support beams (for structure, strength and ease in lifting). The finished pools are shipped in one piece to the installation site.
A quick overview of their installation reveals both similarities and differences between fiberglass and Gunite pools:
1. The installation process begins by carefully and precisely marking the pool layout on the ground with spray paint.
2. The pool area of the yard is excavated, and the hole is carefully prepared to achieve the proper shape and depth. The excavation crew refers to a “dig sheet,” which provides the exact specifications for depth and width when creating the hole.
3. A base layer of crushed limestone or gravel is laid in the excavated hole to create a bed for the swimming pool. These two materials do not saturate like sand and stay in place with moisture. Some pool builders use a sand backfill with the possibility of creating voids down the road. Houston is not an ideal place for a sand backfill with the amount of water received.
4. The pool is set in place using an excavator or a crane. The installation crew will carefully work to insure that the pool is resting on a solid foundation and level to prevent it from shifting over time.
5. The installation crew now begins working on finishing steps! The pool is filled with water and the space beneath and around the pool is plumbed before beginning to backfill it with gravel or sand. The crew will take care to raise the water and gravel or sand levels together in order to equalize the pressure.
6. The final step of installation is pouring the pool deck! Once the pool is backfilled, , the crew is ready to pour concrete for the patio and install the coping, which is the lip that finishes off the edge of the pool and connects it to the patio. Installing the patio can take from two to five days, depending on the complexity of the job.