How much does moss growth affect roof life span?

[Frank L. Bartlo]

I frequently find roofs that are relatively new, but have a considerable amount of moss growth, typically if there are tall trees near the house.

It stands to reason that the roots of moss and similar plants would cause some breakdown of shingles, but to what degree?

Any info would be much appreciated for a current report I'm working on and for future reference.

[Michael Larson]

From the manufacturer of Z-stop

Why remove moss or fungus at all?
Moss can severely damage, even destroy, a roof, by breaking down the fibers in the shingles, forcing them apart and allowing leaks to occur. Many roofs must be replaced prematurely due to damage caused by moss that has been neglected. Fungus, algae and mildew are less damaging to a roof than moss, in terms of actual destruction. However, it looks terrible: the roof on most houses is one of the largest visible surfaces, and when it is covered with fungus, algae or mildew, it detracts from the appearance of the whole house. Another reason is that fungus reduces the ability of the roof to reflect away light and heat, thus making for higher air conditioning bills.

[Roy D. Cooke, Sr]

I understand removing Moss does damage the roof .
The Zinc strip mentioned above will kill moss and I do recommend it in Damp shaded locations all the time .
Even using a pressure washer is not recommended.

Cookie

Added.http://www.inspect-ny.com/roof/Shing....htm#bannertop

[Larry D. Kage]

A stiff broom seems to work well if one gets to it before the moss is too dense.

[Michael Larson]

Originally Posted by lkage

A stiff broom seems to work well if one gets to it before the moss is too dense.

It will return unless a zinc strip is added near top or the local microevironment chages.(More sun, less dampness, etc.)

[Larry D. Kage]

dbl post

[Larry D. Kage]

Originally Posted by mlarson

It will return unless a zinc strip is added near top or the local microevironment chages.(More sun, less dampness, etc.)

Well, yes, trimming back the trees/shrubs (recommended) helps to make it more permanent.

[Kenton H. Shepard, CMI]

Does it damage by holding moisture against the roof which results in freeze damage, or is it actually root growth doing the damage?

[Kenton H. Shepard, CMI]

This looks like pretty good information.

[Brian A. MacNeish]

Some good info there, Kenton, but these guys should get their taxonomy knowledge updated. Moss is not a fungus but has its own division- Bryophytes- within the plant kingdom. But this is just one of the plant types that grow on roofs; others are lichens, fungi and algae. I have also seen small trees sprouting on both roofs and in gutters.