Moss is a plant that grows on the ground or nearby objects. Moss is usually green and soft to the touch. It may feel cool, slimy, and moist, but moss is generally harmless. However, moss can be an annoyance in many areas of your home if it starts growing on your roof.
A common misconception about moss is that it grows only in shady places and rainforests where few roads impede growth. This misconception couldn’t be further from the truth! Moss can grow anywhere there’s dirt or water for as long as light reaches the ground through leaves or grasses surrounding it.
What Causes Moss to Grow on Your Roof?
Moss grows because of the moisture, shade, and nutrients present in your roof. If a top has high humidity for an extended period, that’s a good sign there’s moss in your neighbourhood. Any amount of shade on your roof can also disrupt its structure and lead to moss growth. Compacted dirt, which can accumulate on your roof if you fail to trim bushes or grasses regularly, is another symptom of moss growth. Moss feeds off these elements, so you must eliminate them from your roof before they cause additional damage.
How Will Moss Affect my Roof?
Moss can cause many problems on your roof. It may cause leaks, make it harder for you to clean your roof, and even threaten its structural integrity.
Leaking
Moss may make a patch of your roof look gross and less appealing, but what’s more concerning is that it might also be causing it to leak! Many people don’t notice the problem because they only look at the visible parts of their homes. Their roofs may be leaking, but they never see because water pools under shingles or penetrates the ceiling instead. Over time this can damage ceilings in bedrooms and living rooms while leaking into walls that support the floors below. This leaking can also lead to stained ceilings, mildew, and mold that would otherwise not have grown.
Difficulty in Cleaning
Cleaning your roof is much more complicated, with moss growing on it. If your power washes a roof covered in moss, the pressure may dislodge it or loosen the dirt covering it. During your next cleaning cycle, this dirt will carry the moss into gutters or downspouts. Moss can also be pushed into soffits, which are the space between your roofline and the walls of your home. Getting rid of moss from here is very difficult, so you must keep your roof as clean as possible.
Structural Weakness
Roofs made of wood or thatch installed before the mid-1900s may not support the weight of moss. Moss can also block gutters and downspouts, causing water to pool on your roof, which will indeed cause a leak. It’s best to deal with the problem before it causes more damage.
How Can I Kill Moss on my Roof?
There are several methods for getting rid of moss on your roof, but not all of them are recommended. Some may work for you, but others will add to the damage. If you’re considering a DIY approach, be sure to ask a professional first if it’s safe and effective for your roofing material and location.
Powered Cleaning
The most common method for killing moss is cleaning it with a powered cleaner such as a power washer or pressure washer. This method can be very effective if done correctly at the right time of year. You should avoid using a pressure washer in cold weather as the water pressure can crack shingles and loosen nails. If you use a power washer in warm weather, there’s not a need to rinse the roof with water afterward unless you’re cleaning off dirt or algae.
Even though moss can be easily dislodged by water pressure, it will always grow back unless the underlying cause has been dealt with. The best times to wash your roof are spring and fall, when rain is most common. Once you clean your roof, please leave at least two weeks for moss to grow back before power washing again, so it doesn’t get pushed into your soffits or gutters on your next cleaning session.
Organic Cleaners
Another method for dealing with moss is to evenly spread organic cleaners such as copper sulphate, which you can get from your local hardware store. It would help if you covered the roof in a thick layer of the solution and then left it for up to two days before rinsing it off with water or another cleaner. This will kill moss and damage your roof material and make it easier to dislodge as you clean. Roofing experts recommend using an organic cleaner only if your roof is made of slate or terra cotta tiles. It’s best not to use an organic cleaner on wood shingle or tile roofs because killing moss may remove their protective waterproofing.
Pressure Washing
If you have a small area of moss that’s only visible in certain parts of your roof, it’s best to clean it with a pressure washer rather than power washing your entire roof. This is also useful for cleaning moss from hard-to-reach areas that are difficult to reach or too dangerous with a power washer. You should avoid using this method on shingles as they may become loose if the pressure is too intense. Thatch roofs are also more fragile and easily dislodged by force, so this method should only be done if you have very little moss growth on your roof.
Bleach
There are also commercial products that can kill off moss by balancing the pH levels of your roof. These products come in different forms, such as granules and ready-to-use cleaners. Spray them over your roof in a thick layer and leave them there for up to two weeks before rinsing them off with water. The longer you leave the product on, the more effective it will kill moss because it will still be sensitive to acidity. Unfortunately, these acids are toxic and should never be used on roofs, so bleach should only be applied to an area like walkways or patios that can’t get wet.
Final Thoughts
Moss on your roof can be tough to deal with, but it’s best to find out if there’s a serious issue before it gets worse. Ask your roofing companies if they have any recommendations for eliminating moss or even hiring roofers who can remove the moss for you. Roofers will save you a lot of time and effort, plus they’ll know how to get rid of the moss fast, so you don’t have to worry about it growing back within weeks.
