- Shake shingles trap moisture where the thick pieces of wood overlap. This allows rot, mold and fungus to grow in spots where it is hard to notice or treat. Installing smoothly finished shake over an open lattice of wood supports allows for appropriate air circulation, according to Home Tips. Unfortunately, some contractors install flat shake shingles over a normal roof of felt and plywood. Only shakes featuring deep grooves give enough circulation for installation without an open roof structure beneath them.
- Moss loves the textured, natural wood surface of a traditional shake roof. No matter how charming a moss-covered roof may look, this poses a serious threat to the shingles themselves. Moss traps moisture and makes the roof rot and leak before its time, according to the Cedar Shake & Shingle Bureau. Excessive moss growth also blocks the pathways that allow water to flow smoothly down a shake roof. Cleaning the shake regularly, and treating it with a preservative, helps prevent this problem.
- Wooden shake shingles require more maintenance than asphalt, slate or other roofing materials. If you don't want to climb up on your roof to wash it once or twice a year, try spraying a wood preservative on the shake. Even cedar, which is naturally resistant to some amount of weather damage, benefits from preservatives, according to the Cedar Shake & Shingle Bureau. Use a product designed for wood roof use, and one designed for the specific type of wood used on your roof.
- Old shake roofs used the heartwood of the cedar or other trees. The hardest part of the tree made strong roof shingles that resisted splitting or warping when exposed to moisture and sunlight. Unfortunately, many modern shake roofs use the weaker wood around the outside of the trunk, according to the Consumer Energy Center. This makes them more prone to twisting, cupping or buckling. Improper kiln drying also makes your new shake roof curl up after the first rain, ruining the water-shedding properties of the shingles.