Primary Menu

How to Prevent Mildew and Algae Growth on Your Home.


Mildew vs. Algae: Mildew growth on a log railing spindle…or is it algae? What is that black stuff growing on my house? Mildew, right? Well…maybe not.

For the past few decades, homeowners, contractors, and paint and stain manufacturers have automatically labeled black spots on paints and stains as “mildew,” but recent studies have shown that as much as 50% of these black growths are actually algae (Yep, that same stuff that grows on rocks. Yuck.).

When researching log and wood home care and maintenance, many folks will ask specifically for a stain that resists mildew, and rightfully so – mildew resistance is important! But did you know that the fungicides added to paints and stains to resist mildew growth don’t completely prevent algae growth? For strong resistance to algae growth, an additional algaecide needs to be added to the paint or stain.

That’s why Sashco boosts all of our exterior coatingsColorfast pre-stain base coat, Capture® Log Stain, Cascade® clear top coat, Transformation Log & Timber Stain and Transformation Siding & Trim Stain with an algaecide. Sashco is the only manufacturer of specialty log home stains that includes this important algae killer.

So, what’s the big deal?

Let’s get educated:

Mold and mildew are fungi that thrive in moist environments with low light levels. A common area for mildew growth is under the protected eaves of a home, although it can occur in partially shaded areas, as well. (And most folks can find mildew growing in their shower, too.)

Algae are plants that thrive in moist environments and use sunlight for photosynthesis; that’s right – they need sunlight to live. Algae comes in a variety of colors, from greens to yellows and browns. Dirt and dust often stick to algae, making it appear black. 

Left unchecked, both can force their way into the stain or paint, damaging it and shortening its lifespan. This means you have to re-paint or re-stain sooner and more often, which is time-consuming, budget-consuming, and back-pain inducing.


3 Things You Can Do To Help Prevent Mildew and Algae Growth on Your Log Home: