Elastomeric Paints Can Stretch the Life of Masonry Exteriors

Cracks can result when masonry walls expand and contract in response to changing temperatures. The problem is compounded if water gets into a crack and freezes. Since water expands when it freezes, it causes the crack to expand further ... up to nine times its original size! Since it is not unusual in many parts of North America for a series of freeze-thaw cycles to occur in rapid succession, the number and size of these cracks can expand exponentially.

Thanks to advances in paint technology, a special type of paint has been developed to address this problem. These paints - known as "elastomeric wall coatings" or EWCs - are applied in very thick films that seal out moisture. They also bridge existing cracks and prevent additional cracks from developing, enhancing the beauty of your home for years to come.

Elastomeric wall coatings made with 100 percent acrylic binders are applied at a dry film thickness four to five times that of a latex exterior paint (usually 12-15 mils). When temperatures drop, these flexible coatings "stretch" to span cracks in your masonry. Then, when temperatures return to normal and these cracks diminish in size, the coatings contract, returning to their original shape without warping or wrinkling.

The water-resistant qualities of these "elastic" coatings help prevent moisture from penetrating, cracked or porous masonry. But, at the same time, they are able to breathe, allowing moisture from within the home (or from within the masonry itself) to escape to the outdoors as vapor.

Here are some additional tips on using these specialty coatings, courtesy of the Paint Quality Institute:

• Don't skimp on surface preparation. Good surface preparation is critical for good adhesion because of the extra thickness and weight of these finishes.
• Do seal any existing cracks larger than 1/16 of an inch with a top quality all-acrylic or siliconized acrylic caulk or similar product before applying elastomerics.
• Do apply a sealer when coating very porous or very chalky surfaces. + Do apply a sealer before applying the elastomeric top coat on fresh masonry that is less than 30 days old. Although top quality elastomeric paints have superior alkali resistance, a sealer provides added protection against the extreme alkalinity of new masonry.
• Do use a top quality elastomeric coating with a 100 percent acrylic binder for maximum performance benefits.
• Do apply elastomeric paint at the recommended spread rate to achieve maximum flexibility. These coatings perform best when applied in two very thick coats.
• Don't paint elastomeric coatings with any non-elastomeric top coat unless the elastomeric finish has weathered for at least one year.
• Don't paint over elastomeric coatings with a solvent-based top coat.

For more information about elastomeric paints, ask a knowledgeable salesperson at your local paint store, hardware store or decorating center. You can also learn about surface preparation, paint selection and other matters by visiting the Paint Quality Institute's Web site at www.paintquality.com.

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