Extreme heat or cold, moisture, and prolonged exposure to the sun all take their toll on the exterior of our homes. When paint deteriorates, cracks in the substrate are exposed and let damaging moisture penetrate the home. In every region of the country, a painted surface faces tests from the elements, and homeowners are asking for more from their exterior paint than aesthetic appeal and easy application.
Cracking, peeling, bubbling, and mildew can sometimes be avoided by proper preparation of the surface and paint application, but the quality of the paint can make a big difference. In storm-threatened areas of the country, where water intrusion is a major concern, paint failure will leave exposed hairline cracks in the stucco, allowing wind-driven rains to penetrate the home’s exterior. Once in the wall cavity, this moisture can lead to mold and mildew growth, a major health concern in subtropical Southern states. Hurricane Andrew brought major building code changes and calls for better exterior paints to resist the effects of severe weather.
Finding a Better Paint
A good paint keeps severe weather on the outside but breathes to allow damaging moisture vapor to escape from the inside. Color Wheel Paintings and Coatings, of Orlando, FL, found that changing the ratio of resins to pigment (the two main ingredients in paint) and increasing the elongation factor in their product resulted in a high-quality exterior coating that would stretch over any cracks in the home’s exterior. “Our Flex-Lox exterior coating has a 350 percent elongation rate, which allows it to stretch and bridge any hairline cracks in the stucco,” says Tim McLaughlin, vice president of business development for Color Wheel.
Homes in Florida are essentially built on sand, which shifts frequently. A home’s foundation and walls are affected by these shifts, which can cause fractures and cracks to form. Exterior paints or coatings with a high elongation rate can cover existing cracks and stretch to contain the formation of new fractures, while still allowing for moisture vapor from the inside to pass through.
“The raw materials to make this kind of product are available to all the manufacturers,” McLaughlin comments, “but the intense 2004 hurricane season has increased demand for it.” These days just about every paint company offers their version of a waterproof or weatherproof coating. Elastomeric coatings that retain their flexibility and stretchability over a wide range of temperatures are becoming popular solutions for homes in storm or extreme-weather regions. The applicability to a host of surfaces adds to these products’ appeal. “Benjamin Moore’s Elastomeric coatings are for use on uncoated or new masonry and previously painted surfaces such as smooth stucco, concrete/cinder block, fiber cement siding, pre-cast concrete, poured-in-place concrete, and tilt-up construction,” says Allison Marcus of Benjamin Moore, the leading supplier of exterior paint and coatings in Florida.
What to Look For in a Paint
The amount and quality of the resin in a paint or coating will determine its effectiveness. A higher ratio of resin to pigment is a start but, as McLaughlin points out, not all resins are quality resins. “We use 100 percent acrylic resin, and a 60/40 resin-to-pigment ratio.” A paint that uses vinyl acrylic, for example, breaks down within a year in the Florida climate. It is becoming common practice in storm-threatened regions to use a paint or coating system that calls for the application of at least two coats. “Two coats of Flex-Lox will set up to an 8=millimeter thickness. Some homeowners use it as a primer coating and cover it with a finish.”
Finding a Better Paint
Although no code requires paints or coatings to meet a certain water intrusion-standard, there has been talk of making such changes in parts of Florida and regions battered by wind-driven rain. “Benjamin Moore’s entire product portfolio is always being evaluated to determine what, if any, new products or improvements are needed to better serve our end users’ needs,” Marcus states. In addition to these qualities, most storm-resistant paints and elastomeric coatings tout essential breathability, an important feature for homes in regions where moisture retention can be a problem.
A product that uses a greater concentration of a higher-quality resin is suitable for dry climates, too. In Las Vegas, where stucco and masonry are also common building products, efflorescence in the exterior paint is an issue. Efflorescence is caused when rain penetrates the paint film, invades the stucco, and reacts with it to turn into a salt. As this salt evaporates in the hot, dry heat, it passes through the paint, discoloring it and compromising its integrity. The 100 percent acrylic resin in a higher-quality paint or coating will retard efflorescence in such climates.