Russ Spence
Commercial Pressure Wash Expert
Why does my roof look so bad?
Pollution, trees, and jet exhaust are the first thing customers think of when they see staining on their roof. They are often surprised to learn that the problem is almost always a growth, such as algae, mold and fungi, which feed on the minerals within the asphalt of their shingles.
Shingles today are made differently than the shingles of just 15-20 years ago. Shingles in the past were made up of a thick cellulose (paper) mat, saturated with asphalt, and toped with granular. Most shingles had an expected life span of 20 years. Growth didn’t occur on these shingles until the latter part of their life span because the oils would continually leach to the surface, preventing growth. In the final years, the oils would become mostly dried and dissipated, and growth would begin. It was often in the form of deep rooted systems, such as those in the family of fungi commonly referred to as moss.
Most shingles today are made with a thinner layer of asphalt, separated in the center, by a dense layer of fiberglass. Oils do not pass through the layer of fiberglass. This is good for the bottom layer of asphalt. It protects this layer from degrading, and helps shingles last longer. However, the top layer of asphalt is very thin, and does not benefit from leaching of oils from the bottom layer. In a short span of time, this top layer loses its oils though weathering and evaporation, leaving the remaining organic matter vulnerable to all sorts of growth. The dense layer of fiberglass prevents most deep rooted growths, so most are single cellular in nature, thus creating the look of a stain.
Will this problem damage my shingles?
Yes. The type of growth you have determines the amount of damage. The least damaging are the algae and molds. These growths hold moisture, which very slowly causes premature degrading. The worst growth we encounter is lichen. We find it growing on roughly 30% of the roofs we clean. Lichen is such a hardy feeder, it creates enough damage to the roof, in as little as 3 years, so as to cause granular to fall off.
Customers often forget the visual damage growth causes to their roof. Most roofs are replaced today due to the way they look. We are finding many people are replacing their 25 year roofs in as little as 10 years because they look so bad. Often a roof cleaning is all they need.
What about fungi resistant shingles?
Shingle manufactures have recently begun marketing shingles as algae and fungi resistant. They achieve this by baking a micro thin layer of copper sulfate on the outside of roof granular. Every time it rains, the copper releases ions, which tend to kill growth spores. However, such manufactures warranty the effects for only 10 years; where as the shingles are warranted for 25-50 years. As the copper sulfate becomes weathered away, the shingles begin to develop growth. Eventually, even these shingles will need to be cleaned.
Why do most roofs have growth on the North side?
Ultra violet rays of the sun kill most growth spores from algae, mold, and fungi. They also rapidly dry the surface after a rain, making it impossible for them to feed.
Pollution, trees, and jet exhaust are the first thing customers think of when they see staining on their roof. They are often surprised to learn that the problem is almost always a growth, such as algae, mold and fungi, which feed on the minerals within the asphalt of their shingles.
Shingles today are made differently than the shingles of just 15-20 years ago. Shingles in the past were made up of a thick cellulose (paper) mat, saturated with asphalt, and toped with granular. Most shingles had an expected life span of 20 years. Growth didn’t occur on these shingles until the latter part of their life span because the oils would continually leach to the surface, preventing growth. In the final years, the oils would become mostly dried and dissipated, and growth would begin. It was often in the form of deep rooted systems, such as those in the family of fungi commonly referred to as moss.
Most shingles today are made with a thinner layer of asphalt, separated in the center, by a dense layer of fiberglass. Oils do not pass through the layer of fiberglass. This is good for the bottom layer of asphalt. It protects this layer from degrading, and helps shingles last longer. However, the top layer of asphalt is very thin, and does not benefit from leaching of oils from the bottom layer. In a short span of time, this top layer loses its oils though weathering and evaporation, leaving the remaining organic matter vulnerable to all sorts of growth. The dense layer of fiberglass prevents most deep rooted growths, so most are single cellular in nature, thus creating the look of a stain.
Will this problem damage my shingles?
Yes. The type of growth you have determines the amount of damage. The least damaging are the algae and molds. These growths hold moisture, which very slowly causes premature degrading. The worst growth we encounter is lichen. We find it growing on roughly 30% of the roofs we clean. Lichen is such a hardy feeder, it creates enough damage to the roof, in as little as 3 years, so as to cause granular to fall off.
Customers often forget the visual damage growth causes to their roof. Most roofs are replaced today due to the way they look. We are finding many people are replacing their 25 year roofs in as little as 10 years because they look so bad. Often a roof cleaning is all they need.
What about fungi resistant shingles?
Shingle manufactures have recently begun marketing shingles as algae and fungi resistant. They achieve this by baking a micro thin layer of copper sulfate on the outside of roof granular. Every time it rains, the copper releases ions, which tend to kill growth spores. However, such manufactures warranty the effects for only 10 years; where as the shingles are warranted for 25-50 years. As the copper sulfate becomes weathered away, the shingles begin to develop growth. Eventually, even these shingles will need to be cleaned.
Why do most roofs have growth on the North side?
Ultra violet rays of the sun kill most growth spores from algae, mold, and fungi. They also rapidly dry the surface after a rain, making it impossible for them to feed.
