Discussion of the Seasonal Challenges Facing Exterior Painting Projects from a Washington, DC area Contractor
Scheduling exterior projects is always a little bit of a challenge for a painting company, because we cannot control the weather. We can buy the paint or stain, collect our equipment, and get our crew ready and onsite – but if the sky does not cooperate, we have to turn right back around and head home, scheduling the work for another day.
Why is that? Because coatings (coatings is an industry term for paints, stains, glazes, and any other finish that covers the surface of a substrate) do not dry, cure, and form a film correctly if the weather is too cold or too moist. The chemical components in most modern coatings contain water (there are still oil-based paints and stains out there, but they are slowly being replaced by water-based products due to the ease of cleanup, quick drying time, and environmental friendliness of water-based paints), and the way that the coatings dry and cure requires that water to evaporate, turning the substance from a liquid film to a solid coating. If the air is too humid, the water will not evaporate in its proper sequence, and the coating will therefore form inadequately and the entire paint job will likely fail. In the cold, not only is there insufficient heat to encourage the water to evaporate (it may, in fact, go in the opposite direction and freeze, which causes almost certain coating failure), the cool air can hold far less moisture and is therefore saturated much more easily, making it nearly impossible for water to evaporate.
For this reason, work on exterior projects stops during the cold season in temperate climates like the Washington, DC / Northern Virginia area. Once the temperature warms up, everyone in the industry – customers and contractors alike – are excited to resume exterior work. Early Spring is a good time to get your home beautified for summer, to up your curb appeal in time for the early June real estate sales rush, and to clean, stain, and seal your deck in order to protect it from the activity of the coming summer. However, with spring warmth comes an additional challenge, which can make it difficult to schedule exterior work – spring rains.
Needless to say, you can’t put wet paint up on the wall during a torrential downpour and expect it to stay up there and form a strong coating. But what many people don’t understand is that rainfall at any point during the critical drying/curing process can substantially effect the film formation, even if it seems like the coating is already dry. It takes the average exterior latex paint 4-6 hours to dry fully – but the curing process can take up to 24 hours, depending on the humidity. Extreme humidity preceding or following a rainstorm can greatly affect the paint’s dry time. Ideally, exterior jobs should be scheduled when the humidity is average or lower, and when there is no rain in the forecast for the next 24 hours.
Of course, in the Spring, days like those can be hard to come by. So the best bet for you, if you are planning an exterior project, is to schedule and contract your work early, so that it can be postponed until conditions are ideal (or as close to it as they’re going to get), and still meet your schedule, giving you a finished exterior in time for late spring and early summer enjoyment.