A shake roof should last about 25 years if it is given proper care and maintenance. Without maintenance, it can need replacing in as few as 15 years.
MAKING YOUR ROOF LAST
Tho most important thing to do is to clean debris from the roof on a regular basis. Otherwise the shake stays wet longer and as debris decomposes, plants and insects begin to thrive on the roof. It is also good to keep moss, lichen and fungus from growing on the roof. Moss, which grows predominately on the north side, will cause the same problems as debris. Microfungi creates the most damage on the south side because the combination of sunshine and rain gives it a greenhouse effect enabling it to grow deep into the wood. Regular repairs are important to replace split and worn through shake so that the felt underlayment is not exposed. After all, the felt keeps the water out and the shake protects the felt.
CLEANING YOUR ROOF
Most roof cleaners pressure wash. The positive aspect about pressure washing is that the roof looks clean and brand new immediately. The negative aspect is the occasional leak. With pressure washing there are generally more repairs needed due to the high water pressure damaging the shake. In the best case scenario, the life of the roof has been reduced. To get the immediate "brand new" appearance, the upper layers of wood are stripped off of the shake. The goal is to get more years from the roof. That's why Dr. Roof uses an air system to clean off the debris and let the rain wash away the moss, lichen and fungus after treatment with Guardian Roof Cleaner. Air and rain are much more gentle than pressure washing. Depending on the amount of debris collecting on your roof, you might need to clean it twice a year or as little as once every 3 to 5 years.
TREATING YOUR ROOF
Most roof cleaners use an oil based product with a copper or zinc chemical to act as the fungicide. These products do kill the moss but they can also harm anything in their path. If you are concerned about the plants and animals around your house, I don’t recommend a metal based product. The oils applied to the roof are also a smelly waste of time. Less than 3% of the wood mass has oil in it to begin with. The reason roofers have always used oil is because the shake appear to be drying out. But they are actually just severely damaged by the microfungi growing on the south side. A good example that proves that point is this: A roof that is only 15 years old, having never been treated with anything, will need many repairs and sometimes needs to be replaced. However, under each of the metal flashings and vents there is a streak running down the roof. This is due to zinc leaching out of the metal every time it rains. The shake beneath that flashing are fine and still have years of life left in them. Yet the shake sitting right next to it are so damaged that they can be crushed with your fingers (as if they had dried out). The zinc leaching out is acting as a fungicide. So the longevity has nothing to do with oil, it’s just a matter of reducing the amount of growth within the shake.
