What you do not want to use to clean the moss from your roof with is TSP, bleach or chlorine based products these will kill moss but also damage your home. Those products are not designed to stick to pitched roofs; they clean unevenly and usually leave stains on the roof shingles or tile. Along with staining your roof, these products contain strong chemicals that severely dry out your roofing material, causing cracking and making your roofing material susceptible to wind damage. These types of hazardous products may also kill any plant, shrub or section of lawn as it runs off of the roof. There are products designed specially to clean moss from roofs, a good product will be designed to stick to even the steepest pitched roof while attacking the roots of the moss. A good roof washing product should be environmentally safe so that it will not harm your yard, it should also be a non-staining product.

Roof moss needs to be removed from the root that is why you need to find a roof cleaning product that attacks from the roots. A garden style pump sprayer is a great way to apply the roof cleaner to the roof moss. The best way to remove the moss is to brush the moss off with a medium bristle scrub brush; the trick to this is to only brush the moss when it is wet with the roof moss cleaning product, that way the roots come right off. Brushing roof moss dry or with the wrong product will only remove the "flower" of the moss and soon the moss will bloom again. After the moss has been brushed from your roof, rinse thoroughly with water, it is also a good idea, once the roof has been rinsed to apply one more coat of roof cleaner and let it stay on the roof.

Keeping the moss from returning is the next battle you will face but I have a couple of tips that will keep your roof looking clean. The first of which is to buy some rolled zinc, make sure that it is at least 3.5" wide, roll it out and secure it along the ridge of your home( on the side that the moss was on) and as it rains the zinc will release metal ions, coating the roof that will prevent any future growth. This has been proven to be an effective solution. The alternative is to coat your roof once or twice a year with a roof cleaner, I recommend twice, once mid May and again in late November.

Clean your roof first then periodically spray a roof cleaner on your roof or add the zinc flashing and your roof will last and look beautiful again.