Mold Damage on Roofs

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The lifespan of a residential property roof can generally range from two to five decades if the successive occupants maintain it properly. Unfortunately, a lot of homeowners allow roof mold damage to fester, which can drastically reduce the longevity of a roof. Mold growth on roofs is one of the most costly problems when homeowners fail to take action and simply allow the growth to continue.

When it comes to the structural integrity of the roof on any given house, roof algae and mold are two of the biggest enemies. Other serious threats to a rooftop include moss and mildew, the growth of which can persist when homeowners fail to address the problem.

Let’s break down the issues posed by algae, mold, moss and mildew.

1. Algae

Dampness and Humidity Spawn Algae

Characterized by its black-green hue, algae growth can eat away at shingles and eventually lead to roof rot. The problem is rooted in rooftop moisture deposits, where spores nest and slowly spread into algae across shingles and shakes. Algae is also common in gutters due to the presence of water. The two conditions that are most likely to spawn algae are dampness and humidity. Algae growth is most prevalent along the Pacific Coast and throughout the Midwest, Northeast and Deep South.

2. Mold

Unlike algae and moss — which, in their proper settings, are healthy, natural flora — mold is a more clear-cut problem with hazardous health effects and no aesthetic value. Mold is easy to spot due to its rancid smell and slimy, unattractive appearance, which is characterized by black, brown and dark-green blotches. As with other damaging growths, mold is the result of moisture deposits. Mold is most likely to develop on wood and drywall surfaces where water has been absorbed.

3. Moss

Easily recognizable because of its fuzzy texture and forest-green color, moss can be an attractive feature on a rooftop — depending on the homeowner’s design scheme and surroundings — but moss can also have detrimental effects. Moss is attracted to moisture, and therein lies the problem. As moss spreads, it carries increased amounts of moisture, and this can set into the wood of shakes and shingles and cause a roof to rot.

4. Mildew

Like mold, mildew is a cancerous growth on damp surfaces. Characterized by its powdery appearance — which can range from black to light grey and even pink — mildew is displeasing to the eye and detrimental to the health of those exposed for prolonged lengths of time. Mildew growth is likeliest to occur in warm, wet environments and often spreads on roofs with poor drainage. More so than other harmful growths, mildew spreads fast.

The common denominator between algae, mold, moss and mildew is that all are the products of damp settings. In a rainy area, a roof that lacks sufficient drainage could be especially susceptible to any one of these four growths. A house surrounded by tall trees can also be vulnerable if dampness from overhanging branches passes onto a roof.

All four types of growth are dangerous to the structural integrity of a roof because they breed moisture, which can degrade the quality of wood shingles and shakes. Mold and mildew are most dangerous of all due to their detrimental health effects. Mold, for example, causes respiratory problems in the occupants of affected households.

How to Stop Roof Fungus

Conditions for mold and algae

The spores of algae, moss, mold and mildew travel through the air, but they don’t nest on rooftops unless certain conditions are in place. For example, if a house is situated in a clean and dry environment, none of the growths are likely to occur. Likewise, a house with sufficient roof drainage is more likely to avoid the problem. That said, the most effective way to prevent the problem is with biannual inspections of your roof.

On houses that are highly vulnerable to rooftop formations of algae, moss, mold and mildew, the problem can also spread indoors if gaps exist where standing water can leak into the attic. If a fungus has developed along moisture deposits and water puddles on the roof, any path that leads indoors will carry the malignant growth into your home.

With biannual professional inspections, you can identify such problems before they impact the structural integrity of your roof and the sanitation of your house. That said, there are steps that you can take as a homeowner to reduce the chance that fungus spores will develop into harmful growths on your rooftop. Perform the following steps each spring and fall to help keep your rooftop free of algae, moss, mold and mildew:

  • Trim branches — Cut away any branches that hang over your rooftop. Preferably, there should be a distance of at least three feet between your house and the farthest extensions of the nearest trees.
  • Clean the gutters — Clear any obstructions or buildups that form along your gutters — be they dirt piles, pine cones, foliage or tree parts — to ensure water flows freely and drains from your roof as intended to allow for the continued passage of rainfall into the ground.
  • Treat the roof — If your house is situated in an area where roof algae and fungi are common, consider a more resistant type of roofing material. Alternately, have your shakes or shingles treated for moisture resistance. The investment could spare you from the costly and often unexpected expense of a rotted roof.
  • Add ridge vents — As long as your roof and attic can “breathe” properly, they are less likely to generate moisture. If your house lacks roof ridge vents, consider adding them, as vents can reduce the possibility of moisture deposits that harbor malignant growth.

Along with biannual roof inspections, the above-listed steps can help drastically reduce the possibility of harmful growths on your roof and extend the overall life of your roof.

How to Clean Roof Algae

The easiest way to clean algae off roofs is with the use of bleach and water. As long as the problem has not advanced to the point where the roof is seriously compromised, a 50/50 mix of bleach and water should clear away the algae and restore the cleanliness of your shakes or shingles. Bleach is the active ingredient that kills algae on contact.

After mixing bleach and water in a large plastic bucket, gradually spread the mixture over your roof with a mop. The algae should quickly loosen up and wipe away from the shingles as you cover the roof, foot by foot. Once you have finished, hose the mixture off the roof. This stage is a good time to check your gutters for any obstructions that could possibly impede the drainage process.

To prevent the re-growth of algae, line the shingles with copper flashing to inhibit any further development of algae, which is allergic to copper. Better yet, contact a roofing service professional to perform this service. A licensed roof cleaner will know how to keep balance and perform the job fast on a residential rooftop.

How Do Roof Leaks Happen?

Water damage in holes and gaps in roofing

When fungi growth leads to roof damage and leaks, the problem becomes critical. If the damage has already traveled to this extent, the task to restore your roof will involve more than just a cleanup. If water is now leaking into your attic, you will need to identify the source of the leaks and the extent of the damage both externally and internally. In cases such as these, the best option is to hire a roofing professional to examine the situation and perform the needed repair work.

Roof leaks can stem from various types of damage, which are often the result of gradual fungi growth. Some of the most common sources of roof leaks include:

  • Damaged shingles — If holes or gaps exist anywhere along the shingles, water can make its way underneath and eventually stream to weak spots that expose the interior of the attic.
  • Missing shingles — A heavy storm can blow shingles off a roof, especially on houses where the shingles have been weakened due to the growth of moss, mold, mildew or algae.
  • Damaged flashing — Gaps or holes in the flashing can also serve as entryways for water into your attic.
  • Incorrect roofing — If the material on your rooftop is unsuited to the design of your roof, it could be more susceptible to compromise from the malignant growths that harbor moisture, which in turn can weaken the roofing and cause holes to form that lead to your interior.
  • Ice dams — Freezing weather can be dangerous to the stability of a roof, especially when ice dams form along the edges. Ice dams can prevent water from draining off the roof. As the water backs up behind the dam, the water is liable to leak into your attic.

Any time a major storm hits your area — be it a blizzard, snowstorm or hurricane — you should contact a roofing professional to inspect your roof the moment the storm has passed. Storms can rip away random parts from a roof and render interiors vulnerable to wind, water and the further spread of malignant, toxic fungi.

How to Identify Roof Mold Damage

The problems that stem from the growth of algae, moss, mold or mildew will have already become an urgent matter by the time internal leaks become evident. The following indicators serve as evidence that your roof has been leaking water into your interior.

  • Water marks — If you spot marks of water along the ceiling or walls of your attic, chances are your roof has developed a gap or hole.
  • Discoloration — If the paint or finish in your attic room has become decolorized in places along the upper walls or ceiling, the marks are likely the result of a leak.
  • Dark spots — The formation of dark spots in the paint on the ceiling of your attic room is likely due to moisture impressions.
  • Peeling paint — If the paint has started to peel around the dormer windows or along dropped portions of the ceiling — such as around a skylight — you probably have a roof leak.
  • Peeled plaster — When cracks or blisters form along the upper walls or ceiling of your attic room or top floor, water has somehow gotten through to those areas.
  • Chimney mold — If you spot mold formations around your chimney, it could only be due to the presence of water where it doesn’t belong.
  • Rotting wood — When signs of rot become evident along the wooden interiors of your attic, water from the outside is the probable culprit. This problem is common around dormer windows and skylights.
  • Discolored rafters — If the surfaces of the rafters take on unnatural tones — such as red or rust — the wood has likely absorbed water from a leak up above.
  • Crumbling drywall — If the quality of drywall in your attic room or top floor has recently changed for the worse, the deterioration is likely due to the absorption of water from a nearby leak.
  • Musty attic — If your attic has recently been plagued with musty smells, the absorption of moldy water into the wood or drywall is the likeliest cause. If you spot mildew along the walls or ceiling, there is definitely a leak in your roof.
  • Internal seepage — If your interior is anything less than 100 percent protected from raindrops and watery breeze whenever storms rage outside, your ceiling is not completely solid.

When water is absorbed into wood and drywall, mold and mildew germinate at the surface. The growth can occur in a matter of days and permeate the affected quarters with musty smells and harmful air-bound toxins.

Roof Mold Health Risks

Health Hazards of Mold

Black mold on roof shingles is most common on homes in rainy, storm-plagued climates, especially on ill-equipped homes with insufficient roof drainage. Many of these same homes are vulnerable to roof leaks, which allow water and mold growth to spread into attics, top floors and more. Mold has been linked to allergies, respiratory problems and asthma in exposed individuals.

Once the growth of mold has spread into your home’s interior, it can render your house a health hazard, especially as the toxins circulate through your HVAC system. If mold growth is a problem inside your house, contact licensed professionals who are equipped to assess the damage, pinpoint the source, remove the mold, sanitize the affected areas and perform the needed air filtration.

Roof Replacement Services in Virginia

Since 1993, Sunshine Contracting has been the leading supplier of exterior remodeling services in northeast Virginia. Our range of services covers everything from roof replacement to gutter work on homes throughout the counties of Arlington, Fairfax, Prince William, Loudoun and Stafford.

To resolve issues like mold damage and algae/moss growth on your rooftop, contact Sunshine Contracting for a free estimate. To learn more about our work, visit our services page.

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