Serving New Jersey & Eastern Pennsylvania

Importance of Keeping Your Roof Clean

Moss Shingle

It is no secret that the roof of a house is the most sturdy and unflinching protector against the elements. And when we talk about the elements out there, they are not just seasonal. Most of the exterior of the house like siding and windows come into immediate focus if we notice any impact or unsightly damage. But, the roof is often ignored to withstand the impact of the outdoor elements tacitly. Just like the windows and the outdoor siding of a house its roof also needs regular cleaning.

But, don’t the elements also keep the roof clean?

It is true that sunshine and rain help in keeping the roof clean. But, not all parts of the roof get the needed amount of sunlight, nor do all the roof elements absorb the moisture and other natural elements that affect it negatively. Unlike in the arid areas out west, most houses in the metropolitan suburbs like Moorestown, NJ, Voorhees, NJ, and Mount Laurel, NJ are surrounded by trees which in turn prevent some areas of the roof from getting enough sunlight. There are a number of natural elements that cause your roof to look dingy, dirty, and aged with dark stains, and areas that seem discolored. Most of this malaise is generally caused on your roof by three common elements:

  • Algae
  • Moss
  • Fungus

The elements along with dirt can make your roof look dirty, aged, and unwell.

What is Algae?

At times homeowners consider the ugly black streaks on the roof as normal wear and tear of the roof. In reality, it is an alga of the genus Gloeocapsa, called Gloeocapsa magma or GM, a bacterium that causes those black stains. Due to tree cover or other reasons, when the roof is not getting enough sunlight, GM forms a blue-green cover over your roof and starts discoloring. The GM feeds off of the asphalt and limestone roofing shingles. The GM also houses several other types of mold that can be damaging to your roof. Persistent cover of algae can help deteriorate the shingles and eventually cause total rot. The mold spores they carry can also cause havoc to your indoor air quality.


Moss is a naturally occurring plant in nature that have shallow roots and love moisture. They are often grown under tree cover in areas with copious amounts of moisture, low sunlight, and no traffic. They also use the debris that trees drop on them to feed on and thrive. Moss spores like those of algae are in the air and attach themselves to buildings and damp spots on bricks, wood, and other objects to grow. Unlike algae, moss is relatively less invasive and dangerous. In itself, moss does not pose any threat to your or your house’s health. Moss neither has any poisons nor does it cause irritation, and its mass does not grow rapidly to gargantuan size to impact your roof. The biggest impact of moss is on wood and wood structures. The extensive presence of moss on wooden roofs can cause roof rot. Of course, the moisture in itself is a danger to any roof. It can weaken or even rot the shingles over time.


Fungi feed on dead, fossilized organic matter. The tar used on roofing shingles is just the ticket and an important food source for fungi. Just like algae, fungi travel in form of spores and attach themselves to various hospitable objects to grow. They settle on the roof in areas that get the least sunlight and are the last to dry after the rain or the morning dewfall. The regular addition of moisture creates an ideal environment for fungi to grow. The fungus first feeds on asphalt and the granule base. The granules on the asphalt shingles are the protection of the shingles and the roof underneath from the harsh and unforgiving effects of the ultraviolet rays of light. The granules and the tar also work to protect against the extreme heat that a roof bears day-in-day-out. When the asphalt granules are eaten away, every extraordinary event mars the shingles. Be it harsh sunlight, extreme heat, or a hailstorm, the shingles get weaker. They crack; they are brittle and they buckle and eventually stop protecting your roof that they are meant to. The penetrating tentacles of fungi and lichens get in and around the eaten asphalt and create pockmarks that wear away your roof.

What Can You Do to Prevent the Damage?

Shingle Washing

According to American Construction, one of the most effective and efficient ways to maintain your roof and ensure its long life is through regular roof cleaning. However, it is important to understand that cleaning your roof is not as simple as grabbing a garden hose and hosing off your roof. Or even try to pressure wash your roof with a high-powered washer hose since it may damage or remove the granules on your shingles which protect your roof from the effects of ultraviolet light of the sun and protects it against extreme heat. In addition, cleaning your roof with high-powered cleaning agents such as concentrated bleach or other corrosive chemicals may kill off the plants and surrounding greenery around your home. Bleach can be used for removing mildew and mold, but it should be used sparingly.

Get Rid of the Debris First:

In a DIY scenario before cleaning your roof, make sure you have removed all the debris from your roof. Suck leaves, broken tree branches, and other debris can block your gutters and drain, so it is important to blow or sweep them away.

Clean Your Roof Only with Approved Biodegradable Compounds:

Although DIY sites recommend using Chlorine bleach, Copper Sulphate, Tri-Sodium Phosphate, Emulsifiers, and other harsh chemical compounds, it is important to note that there are other milder Eco-friendly, Bio-degradable products available in the market to do the job without the corrosive effects of these harsh chemicals. Check with your roofing cleaners for the options available to you for cleaning your roof.

In conclusion, the roof of your house is a living breathing organ of your most cherished investment that can have a long healthy life if properly cared for. And its health has a direct and often costly impact on you and your family inside your house.