Weather can affect exterior house painting and the Pacific Northwest has its challenges. You may already realize that our greatest threat is moisture.
Let’s address the obvious questions:
Can you paint exteriors in rainy weather?
The answer is a resounding “NO!” If your contractor is telling you they have a method for painting exteriors when it’s raining, I would be very skeptical. The only safe way to paint in the rain is to have the areas completely covered and not in danger of taking on any moisture. That means, for most exteriors, you would need a giant plastic enclosure protecting your home. This is a spendy undertaking.
Unscrupulous painting contractors “red-eye” their paint so that it will dry quicker. This is a bad practice, because it voids the manufacturer warranty. Red-eying the paint comprises solvent-based additives that flash off quickly and cause the paint to dry at an accelerated rate. I suggest you tell your painter to hit the road if they try to use this method.
Switching to oil-based paint during a rainy stretch is another practice which is frowned upon. New construction runs year-round, so painters may switch the gutter and/or trim paint to oil-based paint because it skims over and won’t rain off nearly as easily as their preferred water-based counterparts. The problem is that oil-based paints do not hold up to the elements and will crack and peel off the gutters. We’ve cleaned up a lot of gutters because of this problem, and sheesh, what a mess! To be fair, when there’s a deadline to meet and the general contractor is on your back and the buyers need to get moved into their home, painters aren’t left with a whole lot of options. As they say, the show must go on. But, with repaints, there shouldn’t be such pressure, so there’s no reason to rush and deliver anything but a proper paint job.
How soon can it rain after a paint job?
This answer varies with humidity, dew point, temperature, wind, paint color and the product that is used. Under normal circumstance, most paints can withstand a shower or two after about 4 hours of drying time. The gutters are at the highest risk for issues because they are the most exposed. The water collects on the top rim of the gutter, runs down the front edge and then collects in big drips underneath on the bottom of the gutters. If the paint hasn’t had sufficient time to dry, this can turn into one ugly mess! If this happens, the best solution is to wait till weather clears then repaint.
High humidity, dark colorants, cool temperatures and reaching the dew point all slow up the drying time. Wind and warm temperatures speed up the drying time. Heat and air movement are critical for the paint to dry.
The dew point will affect the drying time the most. The temperature needs to be at least 5 degrees above the dew point in order for the paint to dry properly. The dew point is the point when moisture appears on surfaces. Unfortunately, if the paint gets wet from dew, it delays the drying process and can cause problems.
What’s the preferred air temperature for painting?
It’d sure be nice if it was sunny and 72 degrees with just a hint of a breeze every day, because then we wouldn’t have to worry about the weather. But, that’s unrealistic, so we’ve had to rely on the drying agents in paint to help us extend our season. Otherwise, there’d only be about three optimal days to paint in Oregon!
When it comes to painting, I am more concerned about the dew point than the temperature because most exterior paints are rated to 35 degrees. If the paint re-wets from the dew, it can ruin a perfectly good paint job.
If you must paint during the off season, a good rule of thumb to follow is to apply paint with an airless sprayer between the hours of 10 am to 2 pm. This way you are starting late enough for the air temperature to raise a bit and stopping to give the paint plenty of time to dry before nightfall.
If, while you are painting, the weather turns on you, take a deep breath, stay calm and think your options through. First, stop painting immediately. Second, check your work site to see if there is any wet paint that is in danger of raining off. If the paint has skimmed over, you may be okay. If you find areas that are washing off, try to find a way to protect those areas, such as draping plastic to provide a cover. If that’s not possible, you may have to let Mother Nature follow course and deal with a mess later. If paint starts raining off your house, try your best not to let it dry out once the rain subsides. If you get to the paint while it’s still wet, flushing the areas with plenty of water will dilute the wet paint and make for a much easier time of cleaning. This is where a pressure washer comes in handy, especially if the paint is dripping onto surrounding surfaces, such as concrete or the roof.
If the paint has cured to the point that it won’t wash off easily, you best run to the paint store for help. There are products, such as Krud Kutter that are made to remove dried latex paint. Just be sure to read and follow the instructions of the label.
And, most importantly, r-e-l-a-x. A paint disaster really is a miniscule problem in the grand scheme of things. As with most problems in life, there is a solution. A glass of wine won’t hurt either. If you’ve done your due diligence and hired a reputable painter, then trust your painter to take care of weather related issues. Weather is unpredictable, so there is no fool proof way to completely avoid Mother Nature’s wrath.
Bottom line – whether you hire a painting company to complete the job or you choose to do-it-yourself, I recommend waiting out inclement weather to help you achieve the spectacular results you hoping to achieve.
Wishing you a happy, sunny day!