This is a frequently asked question from building owners, facility managers, and contractors, when they are contemplating roof restoration options. Put briefly, a good quality liquid rubber roof coating system should last between 15-25 years, but can outlive that under ideal conditions. These figures are not without qualification—the actual service life is based on the materials chemistry, thickness of film applied, exposure to UV radiation and various weather conditions, the installation quality and level of care afforded to the structure. A realistic estimate of service life for a liquid rubber roof coating system is provided below.
Material Chemistry and Formulation Quality
A liquid rubber coating's performance depends not just on its physical form, but on the quality of its material composition. If we look at the common options available options include acrylic-based waterborne coatings (commonly referred to as elastomeric coatings); they are generally cheaper than polyurethanes and polyureas, and provide between 10 to 15 years of roof life in a moderate climate but are prone to collecting dirt and algae and slowly erode under UV exposure.
However, if we consider polyurethane or polyurea based liquid rubber roof coatings (such as those made by Yuru) we find a much larger service life. Polyurethanes and polyureas cross-link to create highly dense and water resistant films with excellent levels of tensile strength and elasticity, and these materials in polyurethane form typically produce 20+ years service life while those in polyurea form produce 25 years, or more, and possess greater UV resistance and abrasion resistance than polyurethane systems. Both the waterproof coatings and the spray applied systems that Yuru manufacture utilize sophisticated resins that were put through a variety of rigorous testing standards according to ISO and CE specifications so that consistent performance can be provided to all types of climates.
This difference is directly down to the molecular structure of polyurethane and polyureas—a system of cross-linked particles that is able to be water resistant and resistant to many chemicals and thermal degradation whilst also having high degrees of elasticity that can accommodate substrate expansion and contraction without fracturing. This is why contractors use premium quality liquid rubber coatings for critical infrastructure where a failed roof system is not an option.
Film Thickness and Application Quality
Perhaps the most important factor relating to the expected service life of a liquid rubber roof coating system is the thickness of the film applied. Typical minimum dry film thickness recommendations for a roof coating vary between 20-30 mils (500-750 micrometers) for membranes not under an extremely high degree of foot traffic, with reinforced systems being specified typically between 40-60 mils. Below these minimums, the material is likely to erode significantly faster under UV light, and give very little resistance to mechanical failure from foot traffic or falling objects, or hail.
However, thickness alone is not going to guarantee excellent results without impeccable installation; the coatings can't have gaps and holes within the film and nor should there be thin patches. To install a liquid rubber roof coating correctly an applicator needs to have good attention to detail, the correct calibrated equipment to apply the material, and be mindful of the weather during application. Temperature and humidity are vital at the time of application and any incorrect application at this time is likely to affect adhesion and integrity of the film. A reinforced system—for example, one that adds fabric to details and vulnerable areas such as seams, penetrations, or junctions, will improve the service life of the system by distributing stress and providing extra protection at these specific points. As a result, a reinforced roof coating system could easily last 5-10 years longer than a non-reinforced system, and the extra material cost would be considered worthwhile given the difference in longevity.
Environmental Exposure and Substrate Conditions
The climate you are in will also affect how long your roof coating will last. A warm or tropical climate is likely to increase your roof’s exposure to UV radiation therefore increasing any rate of polymer degradation. This is due to the UV rays attacking the bonds in the resin system itself which leads to a loss of elasticity and cracking of the films etc.
Polyurea or polyurethane based products have a very high resistance to UV light. The temperature variation is also a key factor; as the substrate undergoes expands and contracts throughout the day which mechanically stress on the roof coating. Polyurethane has great elasticity but all materials have their limits, and over many years extensive thermal cycling will reduce elongation and increase brittleness of a roof membrane.
Maintenance, Repairs, and Lifecycle Management
No roof coating is 'fit-and-forget'. Regular maintenance and proactive repairs are essential for receiving optimal service life from the roof coating you have invested in. Roof inspections of any description should be carried out every year (wherever possible to the building owners specifications and building roof type) to inspect the roof for ponding water, blistering, or peeling.
Any minor defects detected should be fixed as soon as possible. Cleaning of the roof surface periodically (e.g., every few years), removes organic materials such as algae and dirt, which over a few years will start to attack a roof coating—Acrylic-based coatings can sometimes need additional layers of coating applied to maintain their UV resistance and elastic properties whereas polyurethane systems require less frequent coating application although a top coat around the 10-15 year period would add considerably to the overall service life. The Yuru after sales tracking service, along with inspection guides, provided to its customers ensure that building owners receive a long-lasting return on their investment. A polyurethane polysulfide joint sealant or injection grout will perform to last, whilst providing means for targeted remedial action without the necessity for replacement of the complete system. The most reliable and economical long-term benefits of a roof coating come from a combined approach: selecting a high-quality system from a reputable manufacturer such as Yuru, applying it correctly, and ensuring you perform adequate maintenance and repairs when necessary. With proper application and ongoing maintenance, a liquid rubber roof coating can provide a service life of more than 20 years.
