Cedar Shake Roof Care – Special Cleaner

DEAR TIM: I just purchased a home that has a cedar shake roof. My concern is maintenance. The previous owner of the house says I don't have to do anything. My intuition tells me he is wrong. Is there anything I should be doing to maximize the life of the roof? Also, I am very concerned about the possible fire hazard of a cedar roof. Is there a danger? Are cedar shakes really that great when compared to other roofing products? V. E.

DEAR V. E.: Cedar shake roofs have many positive qualities. When installed properly, they are extremely wind resistant. Believe it or not, they actually have twice the insulating value of standard asphalt shingles. Hail does not easily damage cedar shakes. When treated with certain chemicals, cedar shakes can be made permanently fire resistant.

Cedar shake roofs, no doubt, have a certain amount of prestige as a roofing material. That explains why many of the other roofing product companies manufacture materials that simulate real cedar shakes. The texture, color, and appearance of a cedar shake roof is undeniably appealing. However, this beauty comes with a price tag. Cedar shake roofs do require a certain amount of maintenance to maximize their useful life. The enemies of cedar shakes, as you might expect, are water and sunlight.

Many people know that cedar contains high amounts of naturally occurring chemicals which help preserve the wood. These chemicals are called extractives. They dissolve easily in water. Need I say more. In certain conditions, rainfall can leach these chemicals from the cedar shakes in less than 10 years.

Ultraviolet light (UV) from the sun actually causes the surface cells of the cedar to break down. This microscopic refuse is washed away with each rainfall. UV rays also cause very tiny cracks to develop which allows water to drive deeper into the shakes. This simply accelerates the process of dissolving the extractive chemicals.

The key to maintaining a cedar shake roof is to keep it dry. Yes, I realize that sounds funny. What I mean is that after a rainfall, a cedar roof needs to dry out as rapidly as possible. The shakes must be free of moss, fungus, debris (twigs, pine needles, leaves, etc.), or any other thing that can trap and hold moisture. Overhanging tree branches must be sufficiently high so as to provide good air circulation above the roof.

Chemical preservatives are available which can be applied to cedar shakes. These preservatives when applied to clean, dry cedar shakes can dramatically add years of life to a cedar roof. Most of these chemicals can be applied with a hand held sprayer. Professionals who treat cedar roofs for a living have pressurized machines that allow them to do large roof areas in a short amount of time.

If you decide to clean and treat your roof yourself, you need to exercise extreme caution. You need to protect yourself from the dangers of falling. You need to protect your roof from the dangers of cleaning. Cedar shake roofs that are damp, covered with moss, or any object can be extremely slippery. I once stepped on some moss on a low pitched cedar roof and ended up at the gutter before I realized what had happened. Serious and fatal injuries are a very realistic threat.

The use of mechanical power washing equipment used in untrained hands can seriously damage your shakes. Cedar is a soft wood. Cedar that is covered with damp moss is even softer. A power washer that has too much pressure or is too close to the shakes can erode the wood. Simply use some common sense when cleaning.

A great cleaner for cedar shake roofs or decks is oxygen bleach. This non-toxic cleaner is a powder you mix with water. It will not harm the cedar roofing nor anything else it contacts. You must saturate the shakes for about 10 minutes with the solution making sure it does not evaporate. Lightly scrub the shingles with a push broom and rinse with a garden hose. The shakes will look brand new!