Can Using Moss Killer Cause Roof Leaks?

Helps Resolve Leaks

• Moss killer doesn't cause roof leaks -- in fact, it makes it less likely that your roof will leak because moss growth can cause the roof to leak. If there is moss on your roof when it rains, the moss absorbs the moisture from the storm. The engorged moss causes water to go sideways off the roof instead of going straight down the roof. Since the roof is water resistant rather than waterproof, the sideways flow of water may leak into your home.

Damaged Top Layer

• If the top layer of your roof is damaged beyond repair and you plan to re-shingle it, there is no point in using moss killer. Moss killer won't cause the roof to leak in this case, but the moss will be removed when you remove the shingles and redo the roof, so it's pointless to spend time and money on killing the moss.

Compatibility

• Roofers often use zinc sulfate to kill moss because other elements of the roof, such as roofing nails, are made out of zinc. This ensures that the moss killer is compatible with the roof. If the moss killer is not compatible with roofing materials, it may eat through the roof and cause leaks or other damage to the roof.

Pressure Washing

• Pressure washing the roof causes more damage than using moss killer. If you use pressure washing to remove moss from your roof, it may force live moss off the roof -- moss killer destroys the moss so it can be more easily removed. The moss may cling to the roof by its roots while it is being pressure washed; thus, it pulls portions of the roof off, leading to a leaky, or at least damaged, roof.