Now that Labor Day has come and gone, most of the country is entering the stretch run of the exterior painting season. If your house is in need of a new paint job, there's little time to waste: "Paint-friendly" weather is fast disappearing.
"Doing exterior painting in the right weather conditions is extremely important," says Debbie Zimmer, paint and color expert at the Paint Quality Institute. "Fresh paint forms a better protective film when it's applied in moderate weather like that commonly seen in early autumn. If your house needs to be painted this year, you need to paint it now."
To appreciate the urgency, it's important to understand how paint "cures". While latex paint dries to the touch very quickly, it actually takes many hours for it to form the most protective paint film. If the temperature is very hot when the paint is applied -- or more likely as winter approaches, if nighttime temperatures get very cold -- that can adversely affect film formation, and even lead to early flaking and peeling of the paint.
This point is vividly demonstrated on test panels at the Paint Quality Institute. More than 40 years of outdoor testing there shows that exterior paint applied in moderate conditions can last many years longer than paints applied in very hot, very cold, or even very windy weather.
Those extra years of service can offer homeowners a big return on their investment in an exterior paint job. As an example, let's say a new paint job costs $3,000. If it lasts only five years, the annualized cost is $600; but if it holds up for 10 years, the annualized cost is only $300 – half as much!
As the days get shorter and winter approaches, painting in moderate weather is one of the most important factors in getting a long-lasting exterior paint job. Other things that can affect the longevity of a coating aren't so time-sensitive, according to Zimmer.
"To get the most durable paint job, it's always very important to properly prepare exterior surfaces and to use a top quality paint," she says.
Good exterior surface preparation requires that siding and trim be clean and free of dust, dirt, and mildew, so that the new paint can adhere properly. Of course, peeling, flaking, or otherwise unstable paint should be completely removed, and any bare wood primed before painting.
As for the type of paint to use, studies show that high quality 100% acrylic latex paints are the most durable coatings for most home exteriors, including wood, masonry, vinyl and aluminum siding. These paints adhere well, they're tough, and they're very flexible, so they tend to expand or contract with the home exterior when temperatures rise or fall dramatically.
Which brings us back to the weather: As the song says, "For everything, there is a season." When it comes to exterior painting, that season is now.