What’s That Stuff Growing on my Building?

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The rainy season is here again, and while many of us are embracing the warmer weather, we have to be careful of what happens during the rainy, warm time of year. Here in the greater Houston area, we have many different types of buildings that have been made with different types of materials. Despite the many differences from building to building, all building owners have one thing in common … they don’t want to see anything green growing on their structure.

The thought of dealing with mold of any form sends any owner reeling. Knowing the difference between mold, moss, and other green splotches will help you protect your building. Here’s a quick breakdown of what may be growing on your building, how to treat it, and what you can do to prevent any future damage.

Mold or Mildew

Mold or mildew is a fungus that lives by eating the surfaces on which they grow. Mold and mildew don’t usually have any texture to them and are typically green, yellow, or black. Mold and mildew thrive in dark damp areas. If you are inspecting your building, we suggest checking basements, closets, underneath sinks, bathrooms, kitchens, and any other dark damp space that may attract this pesky and often-severe problem.

What's that stuff growing on my building?

Mold can be hazardous to the health of anyone who spends time in the building. If you notice that you feel worse inside a building than outside, you may have a mold problem. Some mold allergies include coughing, sneezing, sinus headaches, difficulty breathing, and other symptoms.

Other warning signs to look out for are moldy odors, signs of water damage, water leaks, or even flooding. If the moldy area is relatively small, you can try to take care of the clean up by yourself, though we do not recommend it. Instead, we recommend you contact a mold remediation specialist to both test and get rid of the mold. This is especially true if it covers an area larger than 3 feet, but again, no matter how much mold you see, there’s more likely hiding somewhere else. Mold remediation is best handled by a professional who knows how to get rid of it for good. We suggest annual or semi-annual checks for mold because of our rainy and humid weather.

Moss and Lichen

Of these fuzzy green patches, moss is the only one classified as a plant while lichen acts more like a fungus. These have more of a texture to them and can be pulled or scraped off surfaces. If you have moss on your building it will typically be green, brown, black, or yellow. Lichen is a pale green, yellow, or even purple color but gets darker if it gets wet.

What's that stuff growing on my building?

The most common place moss and lichen grow is on roofs of buildings. Since the materials of roofs vary, it is hard to pinpoint one way to take care of roof moss. The goal is to safely detach moss from your roof while it is dry so that it can be removed either by hand or naturally with rain or wind.


Algae come in all sorts of colors and survive in different conditions. Typically, algae are green but can be dark-colored and even black. Algae needs the sun to make its own food along with getting nutrients from the surfaces of your building. Algae often grow on roofs with asphalt shingles in shaded areas that stay moist. If you notice streaking marks on your shingles, it may be due to algae growth.

What's that stuff growing on my building?

If not treated properly, algae can cause shingles to lift letting in more moisture and can potentially lead to rot and other damage. It is best to inspect for algae after it rains to see if water collects in the shady areas of your roof. We suggest following your roof’s manufacturer recommendations about methods to clean and remove algae.

What can you do to prevent these damaging green things from growing on your building?

One thing that these pesky growths need in order to survive is water. Having a source of moisture is what feeds them and keeps them growing and progressing and potentially causing damage to your building. In damp basements, we recommend a dehumidifier to stop the spread of mold in darker spots. It is important to clean up any standing water immediately or dry out carpeted areas that get wet. If possible, take the furniture outside to dry out in direct sunlight if they are wet.

What's that stuff growing on my building?

To combat moisture on your building’s exterior can be tricky. Brick surfaces can be pressure washed but need adequate time to dry out. Painted surfaces need to be sealed, scraped, and repainted regularly to prevent moisture from getting underneath the paint’s protective surface. Keeping up with regular maintenance and exterior painting is the most important thing you can do to keep your home or building healthy. Regular maintenance prevents moisture from damaging your exterior walls and creeping into and also damaging the interior of your structure.

At Streamline Paint and more, we have years of experience providing our commercial building customers with regular maintenance to combat these types of growth. We provide pressure washing and painting services so our clients can continuously combat mold, lichen, mildew, and algae. Our painters are also skilled in the repairs that may be needed after the removal of these various substances. To protect your commercial building and/or repair prior damage, contact us so we can ensure your business and those inside it are safe.

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About the author
Kyle Caywood
Kyle Caywood

Owner of Streamline Painting

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