Disclaimer: Getting onto a roof as well as the use of harsh chemicals can be dangerous. Please follow necessary safety precautions and use proper equipment before attempting to get on your roof. If you are unable to do so, we encourage contacting a professional.
We all have seen beautiful homes with lush, full, vibrant foliage with towering trees providing beautiful shade. Sometimes with homes like this we can even see where the greenery appears to have made its way onto the roof which some may find even appealing since it may give the home a rustic-woodsy aesthetic. Unfortunately moss can compromise the integrity of your roof, lifting shingles, eroding at granules (for asphalt roofs) and even causing rot all the way into the decking underneath the shingles.
For removing moss from shingles we always encourage paying a professional to do so, both for safety reasons and so you make sure that the job is done right. If you hop onto your roof and decide to just power wash the moss away it could very easily blow off granules and likely wont even get rid of the moss.
How moss is spread
Moss and/or algae spreads through tiny spores that are carried by wind or water onto a surface where they land and (with enough water) can grow. Sometimes taking years to finally show their presence.
How to get rid of moss
Most home goods stores will carry a Moss & Algae spray that you can buy and tends to be fairly inexpensive for smaller roofs or when dealing with a small affected area. However if you prefer a low cost option, mixing 40-50 percent laundry strength bleach and 50-60 percent water into a spray bottle can generally get the job done pretty well so long as you are aware that this generally will take 2-3 sprays in order to fully remove the moss and any remaining spores.Just be aware of where the runoff is going as many chemicals could easily kill any plants below or stain outdoor furniture
Keep in mind that after spraying you will of course need to rinse off the moss/algae. Be sure to use a low pressure water nozzle for your hose as to not accidentally cause premature wear to your roof. If you decide to instead use a power washer this could not only take off large amounts of granules, but could even break or lift up the singles off your roof, compromising your roofing system entirely.
After this is all said and done, you should be moss free for the next 3-4 years
How to avoid moss and algae
As roofing contractors we install many different types of roofing systems. From stone coated steel, tile, TPO and our most common GAF Timberline HDZ. The Timberline HDZ shingle is in our opinion one of the best asphalt roofing systems you can get for the price. One thing that is fantastic about this shingle is that there are copper and zinc microsites embedded within the shingle granules that help fight against things like algae and moss. You can also get galvanized strips installed on your roof that will aid with this as well, however that option tends to trade off cost effective for the ability to keep your home free of moss and algae.