Tile Roof Care: Prevent A Moss-Induced Leak

Construction & Contractors Blog

A green carpet of moss can look quaint on a roof, but it can bring on a big problem. Moss can lead to a leaky roof, even if you have durable tile roofing overhead. Understanding how moss damages tiles, and then taking steps to remove and prevent its growth, can prevent a major leak or tile damage.

The Leaky Roof Connection

Unlike shingle roofs, moss growth won't cause the tiles to rot or decompose. In fact, the tiles usually suffer no permanent damage or staining from light moss growth. When you see moss taking hold on your roof, you should be more concerned about eventual leaks.

Moss can work its way beneath the tiles. Only in rare cases will this cause a tile to break. It's much more likely that the moss beneath the tile will create a small gap, which allows water to run underneath it. Tiles are attached to horizontal hanging strips, which are affixed the plywood roof sheathing. The nailing strips create a channel for water to run down. When a leak does it occur, it can be difficult to pinpoint which tile along the strip is allowing water in. This can slow down the repair process.

In cold climates, a moss-lifted tile can also increase the chances of an ice dam or eventual tile breakage. Snow slips beneath the lifted tile, where it quickly melts from the heat that radiates through the roof from inside the home. Then, it refreezes because of outside air temperatures. As it freezes, it expands, so it may eventually break the tile. Quick thawing is also a problem, because the water can collect and leak into your home.

Scrub Up Techniques

If moss is invading your tile roof, your best option is to get it cleaned off immediately so you can prevent future leaks. There are two methods for cleaning a tile roof:

  • Pressure washing. This removes all traces of moss using nothing more than the power of the water. If your roof tiles are sealed, the pressure washer may remove it. It may be necessary to reseal the roof after cleaning.

  • Scrubbing. This is done with a scrub brush and a cleaner formulated to kill roof moss. It's more time consuming, but it doesn't usually remove the seal coating.

Both methods can be difficult to do on your own from ground level, and it isn't advisable to walk on a tile roof unless you know what you are doing. It's often a better idea to hire a roof cleaning service, like Allied Roof Cleaning.

Prevention Tactics

Once the moss is gone, you don't want it to come back. The best solution is to manage the environment. Moss favors shaded areas, so trimming back overhead trees to let in more sunlight can help slow moss growth. Zinc strips, which are installed near the peak of the roof, also prevent moss. They work best on flat-tiled roofs because the zinc residue can easily flow over these tiles during rainfall. The residue makes the roof inhabitable for moss.

Clean up moss as soon as you notice it taking hold on your roof, so you can prevent an expensive leak down the road.


6 February 2015

Home Repair Tips for the Novice

When I bought my first home, I was terribly inexperienced when it came to maintaining it. It seemed as if something was always broken. After spending a weekend battling with my oven, I decided that I enough was enough. I started reading everything I could about things related to the home. By the end of my research, I still could not fix my plumbing, but I could look knowledgeable as the plumber explained what was wrong. In an effort to help others avoid the tedious task of reading book after book about plumbing and appliance repairs, I started this blog. Hopefully, this information will save someone from a weekend spent wrestling with their own appliances.