Question: I have been hearing good and bad things about elastomeric paint for stucco. I was almost sure of using it until someone said it might be too waterproof and then stop moisture that gets behind it from evaporating and causing problems. Are there other issues to be concerned about? What are your feelings on it, and would you recommend it?
Thank you, Unni Nair.
Answer: It is very prudent to find out as much information on a building product that is not most frequently used, to see if it is appropriate for your home. While your concerns over trapping moisture in stucco after painting may be legitimate, there should be less chance of that issue with elastomeric paint than with standard latex paint. I will not only answer your question, but provide other suggestions for ensuring a proper paint job on the exterior of your home.
Before spending serious money for something like a total paint job on the exterior of your home, ensuring a few criteria are in order may help prevent severe disappointment on your part. First, make sure the painters of your home are experienced, especially with stucco. There are more and more "college"-style painting companies turning up every year. While some of these have experienced supervisors, many hire rookie teenagers, often students needing summer employment. While it may appear any able-bodied person can slop paint on the outside of a home, proper materials and preparation are essential. The difference between a job that may last a decade or more and one that will start to deteriorate in a year or two is often nothing more than attention to a few details.
Choice of the type of finish may also depend on the current condition of your exterior walls. Is the stucco original without any additional paint, or does it have a few old coats already? Is the painted surface in sound condition, or are there large areas where it has peeled, flaked, chalked or faded? If the surface is unpainted, or the paint is simply dull and not badly deteriorated, painting may be straightforward. If there is existing paint, pressure-washing the entire surface prior to repainting is essential. This will not only get rid of excessive dirt that may prevent proper adhesion of the new paint, it should get rid of most loose or damaged existing paint. Use of a scraper or wire brush for more difficult areas should ensure the prep job is thorough. Priming any bare spots before the finish coats should complete the preparations.
Older, cement-based stucco will often have numerous cracks in the surface and around doors and windows. If these are hairline, nothing may have to be done before painting with an elastomeric finish. One of the major benefits of elastomeric paint is it does bridge these small cracks very well, preventing them from getting worse. If the cracks are larger than a couple of millimeters wide, filling them prior to painting is advisable. Ensuring your painter uses caulking that will be compatible with the finish coat, and has high flexibility, will ensure the cracks are sealed for years to come.
Poor advice
I regularly get inquiries like yours where some unknown friend or source has made suggestions about a particular building product or practice. Some of that information may be valuable, but it definitely depends on the knowledge and experience of the source. Also, there is almost as much poor advice on the Internet as there is good methodology, at least when it comes to home repair. Take all of this information in with some doubt, but look for trends when doing your research. Compare the advice from different sources so you come up with two or three common approaches. Look to see which of these similar recommendations have credible sources. If one of these approaches has been recommended by multiple sources, but they have little to back up their credibility, rule it out. You will normally find the best advice comes from the most reliable sources, who have either experience or science-based results for their conclusions.
Elastomeric paint is an excellent product that not only achieves a long-lasting exterior finish for stucco and other components, but it actually allows has higher vapour permeability than most standard paint finishes. While it looks like a thicker, more flexible, rubber-like coating than regular paint after application, it is actually allows the stucco to "breathe" better. I have no idea about the scientific or technical reasons for this feature, but that combined with the durability makes it vastly superior for stucco finishes. I was also sceptical about this material when it started to come into regular use a few decades ago, but saw the benefits first-hand. Family members had it applied to their stucco home a long time ago, and I saw it last for many years with minimal deterioration. It even bridged a large crack between the main home and addition for almost a decade, before allowing the opening to become visible. Previously, this crack would open and close annually. After seeing the elastomeric finish in that instance, and since on numerous other properties, I am a strong proponent of its use for older stucco homes. It is well worth the additional expense, if you just ignore the claims of some companies that it provides additional insulation value to the walls, which is pure hogwash.
You are to be commended, not only for your skepticism in using a higher-cost product for your home that purports to be superior, but for your exploration of experienced sources of knowledge on that subject. Listen to your source that cautions about the use of elastomeric paint for your stucco, but weigh that against the positive information you find, and you will get your answer. This product is a superior one for painting older stucco homes and should trap less moisture in the stucco relative to standard paint, not more.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
