Tackling Exterior Mold And Mildew
Humidity is pretty much a constant here at the Jersey Shore so there’s rarely an exterior residential project that doesn’t require some work related to mold and mildew problems.
The first step in solving the problem is really educating the homeowner on the causes of mold and mildew. The most common conversation we have is the need to keep trees and bushes away from, and certainly off of, the house to prevent mold and mildew. If we arrive, and there are branches hanging right over the roof or shrubs pushing up against the side of the house, we tell the customer the first thing they’ve got to do is get someone in to trim. We recommend creating about a 2′ perimeter around the house so that air can circulate and prevent mold and mildew from growing. A lot of homeowners do not like the idea but when we explain how the simple effort of trimming to the back of the plant can slow the growth of mold and mildew they tend to give it a try.
If we’re dealing with a historic home that’s painted with oil, we may also have to have a conversation about switching over to latex. A lot of times, people have it in their head that oil is THE best option. But once we explain that oil is likely to mold up again sooner than later, and that latex contains a mildewcide that will hold off mold and mildew for much longer, it’s a short conversation. Once we get past those discussions, we assess the job. We look for obvious mold and mildew on the substrates. We also share that there’s always a chance there may be some rot hiding under the paint. That’s a good moment to explain how me might handle it and how change orders work. If there’s rot, our preference is to replace any affected boards. But if the homeowner is on a budget, we’ll dig out rot and patch it with Bondo Wood Filler or wood fill. But that’s always our Plan B.
We also look at the caulk. It’s especially important to look closely at caulk around trim, doors, windows and butt joints. If it’s split or cracked, or simply has a lot of mold or mildew on it, we immediately know we’ll need to pull it all out and replace it with a higher-grade caulk with a mildewcide. If the home was done with a contractor-grade caulk, it likely won’t have much mildewcide in it, which can contribute to problems. A quality caulk is important to sealing joints and preventing moisture from penetrating the substrate. We use Sherwin-Williams 1050 Quick Dry Siliconized Acrylic Latex Caulk, which comes with a 55-year warranty.
Regardless of whether we see mold or mildew, we soft-wash every exterior with a proprietary mixture of surfactant, water and sodium hypochlorite, which kills mold and mildew spores. We let that sit for about 10–15 minutes, then we gently rinse it and let it dry out overnight. If we see any staining the next day but the wood is solid, we’ll hit that area with an oil primer to seal in the stain. After that, we apply primer and two coats of latex.
In this part of the world, there’s no way to 100% prevent mold and mildew on exteriors, but I feel confident our approach provides a solid defense that protects the look and integrity of our customers’ homes.