By Peter Gibson
Before pools were constructed on a large scale, the typical pool was built using the poured-in-place concrete method, where concrete forms were erected and the concrete poured into the forms. The forms were then removed, revealing the raw concrete. Before the advent of pool paints, most of the pools were left in that state.
As the paint industry evolved, rudimentary paints were used to finish the concrete. When the pool industry matured to mass construction, gunite and shotcrete became the method of construction, and those pools were finished with cement-based materials.
In order to bring pools to a wider audience, the use of vinyl was popularized as it could be installed at a cheaper cost than concrete. Vinyl pools required less construction trades, and most of the work could be done in-house.
Most pool owners would prefer a sturdy concrete pool, however, it is not available in all areas so they settle for what is on offer locally.
The introduction of ICF pools
In recent years, to lower the cost of concrete pools, ICF construction methods have increased dramatically. With this method, more pool owners can enjoy the benefits of a concrete pool at a lower cost, compared to gunite.
Using this method, freeform and rectangular extruded polystyrene forms (EPS) are manufactured to the desired measurements. The forms are set in place and concrete is placed between the forms. The outcome finish is EPS that will receive the pool finish.
Most pool finishes are not compatible with EPS, and therefore it needs to be finished with a cementitious material. This step is not required for vinyl liners, but the use of vinyl has many associate problems (Table 1, page 24). Cement-based materials can be applied over the EPS cement coating. Unfortunately, experience has shown these products do not perform well long-term.
Composite coatings versus vinyl liners
Over the years, some firms have offered vinyl to restore concrete pools. The only reason this is done is because they are not aware of the composite coatings option and superiority. In the U.S., the use of vinyl in concrete pools is very limited, whereas in Canada, vinyl is used as it is well known. With the introduction of composite coatings to the Canadian pool industry, more pool professionals are turning to these products for concrete pool restoration.
After observation of all the candidate coatings to finish ICF pools with, it was found that composite coatings performed the best overall.1 Composite coatings were easier to apply and delivered outstanding long-term performance.
Fibreglass coatings for ICF and polymer wall pools
Apart from the use of fibreglass coatings for ICF pool interiors, is the use in conjunction with polymer wall pools. Polymer walls are usually fitted with vinyl liners, but are an excellent choice to be lined with a fibreglass interior.
The major benefit of polymer walls is they are corrosion resistant and will not rust, and as a thermoplastic, they provide a strong bond for the fibreglass lining. The fibreglass lining is then spray-applied to the pool interior. Most pools are sprayed in about an hour, equating to low labour costs. This kind of pool might also appeal to potential concrete pool customers who would appreciate the benefits of a fibreglass finish, compared to plaster that will deteriorate and require resurfacing.
For vinyl pool contractors, they will be able to offer vinyl and a fibreglass pool, which can bring in more business. A lot of perspective fibreglass pool owners are looking for different shapes and sizes not provided in fibreglass pools, so the polymer, fibreglass, or hybrid pool would work for them.
The fibreglass pool shells are very costly and have to be trucked in and craned onto a property. Now, the fibreglass pool can be created on site at the fraction of the original installation cost. This is a win-win for customers and contractors. In this process, the contractor controls the whole process and is not reliant on fibreglass pool manufacturers.
Although the ICF concept has been available for a long time, there are some more recent concrete forming systems getting a lot of attention because of the inherent advantages over ICF systems.
Marinal system
One such forming system now getting rave reviews from pool contractors is the Marinal concrete forming system from Europe. Most pools in Europe are constructed using formed concrete and not gunite or shotcrete; whereas the North American pool industry most widely employs gunite or shotcrete. With the Marinal system, forms are constructed and concrete poured into the forms.
Here are some advantages or Marinal systems compared to ICFs:
- The interior panel is made from fibre-reinforced board. This is a much stronger material to which the pool finish is applied. If polymer pool finishes are used, there is no need for a step to finish the polystyrene with a cementitious product.
- Fibre-reinforced plastic (FRP) polymer pool finishes work best with this method. The polymer is sprayed to the pool interior that conforms to the shape and size; and cutting and sizing of vinyl liner rolls is eliminated. This translates into rapid application time. A typical 4.5 x 10 m (15 x 35 ft) pool takes about 90 minutes to spray, and vinyl installations are very time consuming and do not offer a superior finish in the end. Some FRP polymer coatings manufacturers now offer training to apply FRP coatings for concrete forming systems. These coatings can also be used for pool renovation.
- By using this system, contractors gain independence as they are not reliant on gunite or shotcrete contractors. There is waiting for service as businesses can now do everything inhouse (e.g. the pool shell and finish) and this translates into higher profits.
- Very lower labour requirements (e.g. smaller pools would require two men for two days).
- The concrete shell is much stronger, as the concrete is densified by vibration. This translates into a stronger pool shell that is less likely to crack, and cracked pools remains a common problem.
For pool contractors considering other methods to make the pool shell, there are now more options rather than the traditional methods of gunite or shotcrete. If time and labour are more under scrutiny then the Marinal forming system shows superior savings over ICF. Best approach would be to do your own analysis.
Conclusion
Today, there are so many more types of pools to install. This means more choices to make for the pool finish. Whether it is an ICF, concrete, or metal pool, namely, carbon steel, stainless steel or aluminum, composites coatings are adjudicated to outlast and outperform traditional materials such as vinyl and cement-based finishes.
Composites coatings have proven over many years to be the most versatile material to use, no matter what the pool of choice is. As the pool industry awakens to the benefits of composite coatings, more pool professionals will employ these products for their pool projects, be it new pools or renovation. S
Notes
1 Refer to Gibson Consulting Services—Material Specifiers for Aquatic Structures.
| Composite coatings | Vinyl liners |
| Sprays 100 m2 (1,076 sf) in less than one hour and requires less labour. | More labour intensive. |
| Conforms to any shape and size. | Very difficult for freeform pools. |
| No cutting, measuring/sizing. Applied by in-house personnel. |
Must be custom made. Must rely on manufacturers. |
| Will not wrinkle and tear. | Wrinkles can occur. |
| No special termination fittings are needed. |
Sites for attachment must be installed. |
| Easy application in spas. | Difficult application in spas. |
| Hard, wear and abrasion resistant, and cannot puncture or tear. | Thin vinyl material. |
| Stays solid over time. | Subject to embrittlement. |
| Offers long-term esthetics. | Vinyl fades out over time and looks unappealing. |
| Long service life. | Short service life and needs periodic replacement. |
Author
Peter Gibson is president of GRC Fiberglass Coatings. Over the past 30 years, he developed fibreglass coatings and linings specifically for fibreglass and concrete pools. Gibson also offers training in the use of these products through the certified applicator training course. He is available to answer all technical questions to resurface concrete and fibreglass pools. Gibson can be reached at resinmaster@gmail.com.
