[Shop-talk] Moss removal from roof?

[Jimmie Mayfield]

On Mon, Sep 22, 2008 at 10:20:27AM -0700, cornerexit wrote:
> I live in the pacific northwet and get a lot of moss on my composition roof
> in the slots between the shingles (see picture in link). A pressure washer
> of sufficient power is effective at removing this stuff but I don't like to
> use one as it accelerates wear on the composition shingles.
> 
> Are there effective moss chemicals that will breakdown the moss to the point
> where it can be brushed out of these slots with a stiff brush/broom, and
> then use a blower or low pressure hose to wash the debris down the roof?

Zinc sulfate will kill the moss.  Be patient as it might take a week or two 
before the moss dies.  Afterwards, you can either brush it off or you can 
let it weather away naturally.  Make sure you wash any overspray from any 
adjacent plants.

A bleach solution will also kill moss.  I used a 1:10 bleach-water concentration
to get rid of moss growing on a retaining wall a couple years back.  You'll want 
to make sure it doesn't discolor or otherwise harm your roof, though.

Jimmie