Your Guide to Outdoor Maintenance — Northwest | Seattle Homes-Real Estate in Seattle-Realtor-Http://www.ThachRealEstateGroup.com

If moss is neglected on your roof, its byproducts will make asphalt and wood shakes shingles more brittle. Apply a moss killer and sweep dead moss off the roof with a broom. Image: MikesMobileWashing.com

Winters in the Pacific Northwest are famously rainy. The effects of a long, damp winter make routine outdoor maintenance especially critical. As weather warms, here are essential outdoor upkeep tasks you should complete.

Clear the roof of moss

“Neglecting moss can shorten the life of your roof by several years,” warns Jim Katen, a home inspector with Associated Master Inspectors in Gaston, Ore. “Moss keeps the body of an asphalt shingle soaked so it tends to get more freeze-thaw damage in the winter.”

In addition, moss produces organic byproducts that make both asphalt and wood shake shingles more brittle. Moss holds moisture against the wood, speeding rot. Moss can even crack cement or ceramic tiles.

Left unchecked, moss on an asphalt shingle roof loosens the shingles’ protective granular coating, clogs valleys, and can even cause pieces of shingles to break off. Let a 2,500 sq. ft. roof go two or three years and you can expect to pay about $700 for a professional cleaning. Ignore it longer and you may need new roofing—a cost of $7,000 to $19,000. The cost of a preventive dose of moss killer? About $20.
 
Begin moss eradication in the fall by applying a moss killer intended for roofs (granules for lawn use contain iron which will stain a roof). In the spring, use a broom to remove remaining dead moss. Spread moss killer along the ridge of the roof and on any remaining green patches. Cost: $20 for moss killer to treat 2,500 square feet of roof. Allow about 3 hours to sweep the roof, clear the gutters, and apply the granules.