Chlorine bleach removes mosses, fungi and mold, but it can damage plants, so dilute it before spraying it on the ceiling. Spray-washing moss from the ceiling is the easiest method to get rid of it. You can prepare a mixture consisting of 50 percent water and 50 percent bleach. Be sure to spray in a downward direction.
Many moss removal companies use zinc sulfate to kill moss on roofs, and it's even sold in home improvement stores under the Moss Out brand. At the end of a session and before taking long breaks, spray the ceiling to move the moss debris into the gutters. If a moss infection has developed on your roof, you can remove it before it becomes severe enough to affect roof performance. The thick lush green moss that takes hold of a roof can be picturesque, giving the house a fairytale feel, like a hobbit.
For high or steep ceilings, be sure to secure yourself with a roof harness before climbing onto the roof to apply moss repellent. Roofers will need to remove all shingles from their old roof, or they may need to remove larger pieces of moss with a pressure washer and then apply the new roof. The moss remover works any time of the year, but is usually applied in early fall, when the sunlight decreases and moss begins to form. So don't be tempted to use a pressure washer or a jet of pressurized water on the ceiling when you remove the moss.
Bending shingles can save time and expense in replacing the roof, since the roofer doesn't need to remove or discard old shingles. Once you've gently cleaned the moss off the roof, consider washing the roof tiles to remove any remaining debris that may harbor moss spores. A number of potential problems can arise if your roofer simply adds a new roof over the existing moss-covered roof. Distribute the moss remover in uninterrupted horizontal lines 2 to 4 feet apart, parallel to the roof ridge.
Unless removed, dead moss will act like a sponge to absorb more water and accelerate the deterioration of the roof structure. While you may not necessarily have to remove moss-covered shingles before installing a new roof, you should consider this. Roof harnesses include brackets that are attached to the roof, with straps designed to stop the fall in case you slip while working on the roof.