Elastomeric Roof Coatings: A Comprehensive Guide

elastomeric roof coating life expectancy, apply elastomeric roof coating

Buildings and roofs can move. They expand and contract with the changes that occur during thermal cycles or the changes in temperatures. Roofs can also be subject to movements of the building that may shift slightly with ground and/or seismic movements, as well as changes in weight loads such as snow and rain.

What is an Elastomeric Roof Coating?

Elastomeric roof coatings are unique and offer some flexibility while installation of these are similar to more commonly used high solids exterior paints while performing in a very superior manner. They are made from resins and polymers (Elastomers) which offer characteristics that allow a coating to stretch while also offering a level of recovery to its original state.

Why Choose an Elastomeric Roof Coating?

Many building owners and contractors are increasingly leaning towards these fluid-applied materials in lieu of more traditional roofing materials. Professional grade elastomeric roof coatings can be used to build a fluid-applied roofing system that in many cases can rival the more traditional roof materials. Fluid-Applied systems offer unique characteristics as they are fluid during application and have the ability to conform to various shaped and surface textures. They can also offer designs to allow for greater than expected movement.

Once cured, the result is a solid, rubbery-like layer that bonds to the roof or underlying substrate having the ability to last for decades with minimal to no maintenance effectively standing up to sun, rain, and temperature changes. Elastomeric coatings work well with a variety of roofing materials and surfaces: metal roofs, single-ply membranes (like TPO and PVC), modified bitumen, and built-up roofs, to name a few. They can also be used on polyurethane foam roofs as well as cementitious materials such as concrete and stucco.

These coatings are commonly recommended for roofs with minimal to zero slope:

Zero Slope Roofs

In years past, roof decks were allowed by Code to have zero or near zero slope, because often roofs were designed to hold rainwater and not quickly drain from the building. This helped prevent overburdening rudimentary storm drain systems of the pre-1970’s. Designing and installing barriers to these types of structures was challenging to avoid saturation into roofing materials and leaks. Certain elastomeric coating can be a viable option to resist the standing water and pressure that results as water ponds on a horizontal surface. There are absolutely no gaps, seams or joints for water to sneak into, making them an excellent shield against leaks.

Low-Sloped Roofs

These roofs are specifically designed with positive flow of surface water but can be vulnerable to standing water if low spots exist. Water typically doesn’t accumulate on low-sloped roofs as much as it would on one with zero slope, but it can still be a problem if not managed well. Elastomeric coatings can work effectively as they create a seamless layer that covers the whole surface, keeping rainwater out.

Performance and Durability in all Types of Weather

Local weather patterns can impact the performance of all building materials. Elastomeric roof coating systems are no exception to this. Being aware of this can help you choose the perfect coating for your roofing situation.

Direct Heat and Sunlight

Elastomeric coatings are made with materials that inherently reflect solar radiation, i.eThey naturally reflect ultraviolet (UV) and infrared (IR) rays away from the roof’s surface and back towards the atmosphere. For instance, some coatings, like acrylic-based elastomeric ones, contain titanium dioxide. This substance naturally reflects sunlight. While it’s commonly used in white coatings, there are now other infrared pigments that are reflective, even though they’re not white.

When sunlight hits the coated roof, the coating reflects the rays sending them back into the atmosphere, instead of absorbing it. This process drastically reduces the amount of heat transferred to the building’s interior often referred to as emissivity. The result is a cooler building and can result in lower utility costs, no matter how warm the weather gets.

That said, intense UV rays over time can wear down or oxidize some elastomeric coatings, so choose a product that is uniquely designed for the building needs.

Rain and Moisture

Elastomeric layers are a great option for rainy climates, but the timing of the application is important. The roof needs to be surface dry when you apply the coating, and it needs a certain amount of dry time to cure properly. If using a water-based acrylic coating should it rain before the coating has fully cured, you could end up with a mess and a coating that doesn’t perform as it should. In areas with a lot of rain, a coating that is not water-based is likely the best option for prolonged wet exposures, especially in climates with freezing and snow.

Cold Temperatures

Many elastomeric coatings require the temperature to be above 50°F (10°C) for proper application and curing, but there are formulations designed to cure at lower temperatures. If you are in a cold climate, look for elastomeric coating types that are especially designed for cold weather environments. These products can cure at temperatures as low as 35°F (2°C) or even slightly below.

Keep in mind that cooler temperatures slow down the chemical reactions or dehydration involved in curing, so you should account for this extended drying time. Lower, more frigid temperatures also come with varying humidity or dew points, which means moisture condensation on the surface or in the air can prevent the coating from adhering properly or curing correctly. Make sure the roof surface is completely dry and choose a dry period for application if possible.

Wind Exposure

High winds can carry debris that may abrade or damage the roof surface. The UV protection provided by an elastomeric coating can help preserve the integrity of any underlying roofing material, making it less susceptible to damage from debris during wind events. Additionally, by maintaining a stable temperature, the roofing material is less likely to become brittle (in cold conditions) or overly soft (in hot conditions), which can affect its performance against wind forces. In extremely windy areas, you might need to inspect the coating more regularly to ensure it remains intact due to problems with an underlying surface or material.

Types of Elastomeric Coatings

Based on the type of project and substrate material you are working with, there are a variety of potential choices. The most common options for commercially available elastomeric coatings are:

Acrylic Elastomeric Coatings

If you are working on a commercial building in a hot, sunny climate, like Southern Arizona or California, an acrylic coating could be a top choice here because of its excellent reflective properties and historical performance for such environments. These are also breathable, allowing moisture from inside the building to escape, which helps prevent mold and mildew growth under the coating or within the building.

Water-based acrylic coatings are very effective in cooling down roof surfaces by reflecting sunlight. They can be an ideal choice for a variety of surfaces and slopes, including metal, asphaltic, and Thermoplastic single-ply membranes.

Silicone Elastomeric Coatings

Silicone roof coatings are known for their superior weather resistance and flexibility. They are recommended in areas with heavy rainfall or where ponding water is a concern, as they provide incredible resistance to water penetration. Silicone’s water-repellent nature means it can stand up to constant moisture without degrading, making it perfect for roofs where water tends to collect. These are also highly resistant to UV light, making them durable in harsh sunlight. Silicone’s durability in wet conditions also means less maintenance and longer life for the roof.

Polyurethane Elastomeric Coatings

For roofs that see a lot of foot traffic or mechanical equipment, such as on a commercial building with HVAC units on the roof, a polyurethane coating would be beneficial. It’s tough, abrasion-resistant surface can handle the wear and tear of regular maintenance activities better than other coatings. This makes it a solid choice for protecting the roof surface against physical damage.

SEBS (Styrene-Ethylene-Butylene-Styrene) Coatings

One of the challenges with some roofing materials is their tendency to fade or discolor over time when exposed to harsh environmental conditions. The chemical structure of SEBS is inherently resistant to oxidation and UV degradation. SEBS coatings are formulated to resist this fading, retaining their color and aesthetic appearance longer than many other types of coatings.

Benefits of Elastomeric Roof Coating Installation

They extend the roof’s lifespan.

Elastomeric coatings add a protective layer that shields any underlying roof system from the harsh effects of the environment like UV radiation, rain, hail, and temperature fluctuations. This prevents the underlying material from deteriorating quickly, thereby increasing the elastomeric roof coating life expectancy. According to the US Department of Energy, reflective roof coatings can reduce surface temperatures by up to 50°F, significantly reducing thermal stress on the material. Historically most light colored Elastomeric coatings will maintain a full sun surface temperature of no greater than 10°F to that of the ambient temperature of the air.

Most coating systems can last 10 to 20 years, but it depends on how thick you have applied it.  Most coating manufacturers offer a variety of warranties and terms, oftentimes the more mils you apply, the longer the warranty term.

They can reduce your energy costs.

Reflective coatings can also lower a building’s interior temperature by reflecting sunlight and UV rays away from the building. These “cool roofs” have been shown to save up to 10-15% of total cooling costs in single-story buildings by reducing air conditioning needs.

They can seal your roof against any water damage.

“Is elastomeric roof coating waterproof?” Considering that elastomeric coatings are composed of elastic polymers (acrylic, silicone, or polyurethane) which are inherently water-resistant, the answer is almost always YES. Plus, these are applied in a liquid state, allowing them to fill in and seal cracks, seams, and joints on the roof surface. This ensures complete coverage, even over irregular surfaces and around protrusions (like vents and HVAC units). Unlike traditional roofing materials that might have gaps or seams, this continuous layer leaves no pathways for water to penetrate the roof.

They are cost-effective to maintain and repair.

If your existing membrane roof is nearing its lifespan, and you are looking for a more affordable solution than full roof replacement, the application of an elastomeric coating system may be the answer. For example, the initial cost of coating a commercial roof (including labor costs) might result in a savings of up to 75% to that of a more complicated roof replacement.

It is important to remember that the best time to put a protective coating on your current roof is before it starts showing any major signs of wear, like regular leaks or parts starting to break down. Doing this now avoids irreparable damage and means you avoid the hassle and extra cost of fixing or replacing parts of the roof that get heavy moisture intrusion. Code can often dictate that roofs with high moisture rates and greater than 40% of the entire roof, often will require removal and replacement of the membrane system. Early detection of minor issues and a diligent response can avoid these extensive costs.

They are versatile.

Elastomeric membranes can be applied over a wide range of roofing substrates. The key is the surface needs to be properly prepared so the coating bonds well and lasts. Before applying elastomeric roof coating, the roof needs to be clean and in a suitable condition. Any dirt, grease, or loose material can prevent the coating from adhering.

Substrate options are vast, below is just a list of the most common surfaces;

  • Metal Roof Panels (Structural and Architectural panels)
  • Single-ply Thermoplastic Membranes (e.g., TPO, PVC)
  • Thermoset Roof Membranes (EPDM Rubber)
  • APP and SBS Modified Bitumen (Torch, Mopped, Cold-Adhesive, Self-Adhesive)
  • Asphaltic Built-up Roofing (BUR)
  • Concrete Roof Decks
  • Spray Polyurethane Foam Roofs (SPUF)
  • Fiberglass and other plastic-based panels

They can be applied to both smooth and textured surfaces with varying slopes. If the roof is cluttered because of skylights, vents, chimneys, pipes, solar panels, roof hatches, HVAC units, and any decorative features, the coating can seal the area around them to protect against weather and the elements.

They can reduce sound transmission into your building

Elastomeric coatings have a somewhat soft, rubber-like texture once cured. This material can absorb and dampen sound waves better than hard, non-elastic materials like metal or tiles. The coating can act as a buffer to reduce the sound of blowing wind, raindrops, or hailstones impacting the roof.

Choose the Best Elastomeric Coating System for Your Project

To get the best and most appropriate coating for your commercial roofing system, you will want to consider the following properties:

  • Check compatibility with existing roof material: The coating should be specifically formulated for your roof’s substrate. For example, if you have a TPO membrane, look for one designed to adhere well to TPO surfaces. Manufacturers usually list compatible substrates on their product data sheets.
  • Elongation and Tensile Strength: Look for a product with an elongation percentage of at least 150%, indicating good flexibility. Tensile strength should be a minimum of 200 psi for durability under foot traffic and environmental stress.
  • Permeability ratings: Understand the permeation needs of the building, roof, and conditions and choose a coating with a permeance rating to fit that need. Non-Permeable coatings can have a perm rating of less than 1 perm which can function as a vapor barrier.
  • Reflectivity and energy efficiency: It should have a high initial reflectivity rating, preferably over 80%, as per ASTM C1549 standard. This can go the extra mile in cutting down your HVAC costs. Tested reflective products are searchable at www.coolroofs.org.
  • UV stability: Look for products with specific UV inhibitors to resist weathering. Products that mention long-term flexibility and resistance to cracking or chalking in their specifications are a wise investment.
  • Adhesion strength: Identify coatings with strong adhesion properties by looking for compliance with the ASTM D903 standard; this means they have been tested for peel resistance on different substrates.
  • Chemical resistance: If your roof is likely to be exposed to chemicals, oils, or pollutants, look for coatings that specify chemical resistance in their product literature. This is critical for roofs near industrial areas or those subject to frequent spills.
  • Viscosity: Find a coating with a viscosity that suits your method of application. Spray applications may require a thinner product compared to roll-on or brush applications. The product datasheet should specify the recommended application method and tools.
  • Warranty: Go for products that come with a solid warranty and strong manufacturer support. Product warranties for fluid-applied systems are available for up to 20 years.
  • Local Building Codes: Make sure the coating meets your local environmental regulations, including VOC (volatile organic compound) limits. Compliance with building codes is also essential for both safety and regulatory reasons.

When evaluating your options, ask for detailed product data sheets from several manufacturers and compare these specifications side by side. Don’t hesitate to contact them directly with any questions or for clarification on their products’ performance attributes. It’s also a good idea to consult with roofing contractors who have experience with elastomeric coatings in your region, as they can offer insights based on local climate conditions and roofing challenges.

A Reliable Solution for a Longer-Lasting, Cooler Roof

elastomeric roof coating system, flat roofs

Looking for a protective roofing membrane that combats leaks, withstands harsh UV rays, and cuts down on energy bills. Polyglass offers elastomeric roof coatings that do just that. Our products are designed to give your roof a homogeneous, water-resistant layer that fights against dirt, fungal, and algal buildup. With Polyglass, you not only get a fluid-applied system that lasts longer but also contributes to a greener planet by reducing waste in landfills. For more information, get in touch with our team.