My house in Bellevue gets a moss on the roof because it is shaded. How can I prevent damage and avoid replacing my roof?

My house in Bellevue gets a moss on the roof because it is shaded. How can I prevent damage and avoid replacing my roof?

My house in Bellevue gets a moss on the roof because it is shaded. How can I prevent damage and avoid replacing my roof?

A lot depends on what your roof is made of, but almost any roof surface in Puget Sound will eventually collect moss, or something like moss, especially if it is always in the shade. Direct sunlight is a great way to keep moss from reaching critical mass on your roof, and there are certainly many things you can do to limit the effect of moss, algae and other things from growing on your roof.

Might be time to remove some trees that are shading your roof

There seems like so little sunlight – and so much cloud cover – in the Seattle and Puget Sound area that it can be a shame to surround ourselves with trees. Actually, you don’t have to do anything to promote the growth of trees. If you just ignore your yard for a few years, you’ll see Douglas Firs, Maples and many other tree saplings popping up everywhere. I have seen Douglas Fir trees growing on the roof of a house in Bellevue on a number of occasions. All they need is a bit of decaying organic material to collect somewhere on your roof – best in a shaded area – and with a bit of rain and some seeds, a sapling will get a head start quickly. Once it has a few inches of root, it will begin to trap its own soil by way of more rotting leaves, etc.. Before you know it, it’s interfering with the very structure of your roof. So, it’s not just moss.

When the roof of your home is permanently shaded from direct sunlight, it can – in certain circumstances – remain damp the whole year round. That means that a sapling root, moss or algae might never be deprived of that essential water it needs all year long. In a high daylight situation, it usually only takes a day or two of great sunshine to parch the new saplings to the point where the die and cease to present a bigger problem, at least for the moment. But shaded areas offer the ideal spot for Mother Nature to come and do her worst!

Consider removing offending trees, or at least some of them. The next best thing – and at a much lower cost – is to trim the lower branches of the tree so that the only part offering shade is the growth above twenty feet or more. This is a far cheaper alternative, and allows you to retain a lot of the tree beauty in your neighborhood, while still giving your house the needed sunlight.

Treating your roof with protective materials

A note of caution – if you have real wood shakes on your roof, you have to be careful with power washing them. The average power washer can strip the flesh off your foot in a careless second, and it can damage a shake roof without you even knowing it. There is a way to do it, but you have to be very careful. An unscrupulous roofing company will happily take your money for a power wash in the middle of the summer. The damage is done, and a few months later, you are paying someone to repair the damage.

Real wood shakes respond well to protective treatments. Natural, untreated cedar shakes do have some protective properties of their own, but exposed wood like that will suffer eventually from the elements. You need to give them that extra bit of help. The first thing to do is completely clean the roof, then let it dry fully. In the middle of a dry August, your roof might be at a perfect stage to take a treatment. There are several ways to do this. Some cost a few hundred dollars in materials and will give you a couple of years of protection. Others will cost a few thousand and will last a lot longer. You can get a gallon of oil for ten dollars, or a can of special treatment liquid for hundreds of dollars. It all depends on how long you want to be able to leave it without having to revisit the problem.

Keep gutters empty

I remember my first house well. It was the learning vehicle for all the things that go wrong. I had absolutely no idea that the gutters at the base of the roof needed to be cleared out once in a while. Well, after a few years, I could see that the rain often rain right off the edge of the butter itself. The downpipes became almost 100% clogged, so it took a few minutes of rain usually to fill the gutters again to the brim. Because the water overflow was focused on a couple of corners, the water was eating several holes in the soil by the side of the house. We had a couple of mudslides before I fully understood what my problem was. It was easy to solve, though. In the end, I simply climbed a ladder to see the gutter from the top. I could see tons of debris blocking the downpipes, and I simply reached in with my hand to pull it out. The two-year old blockage was cleared in an instant, and everything else flowed away quickly. After that experience, I always took a look at the gutters from debris every Christmas. It seemed like the perfect time after all the leaves have fallen.

Keeping your gutters clear means not only reducing the chances of roof damage because of water and debris buildup, but also reducing risk of damage to the outside of your house and grounds. It’s not that hard. You can also get special leave guards to do it for you, but gutters work great with about twenty minutes of servicing a year.

My gutters were, by the way, another place where I plucked several Douglas Fir trees out. One end of the gutter had just enough water coverage, but not drowned, for seeds to germinate and grow like crazy.

I often wonder how long it would take Mother Nature to completely reclaim all of her land should we humans ever have to abandon the place entirely!

More next week!

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