Maintenance

The environment surrounding the structure is an important element for maintenance and roofing longevity. If there are overhanging trees near the roof, the branches should be pruned back regularly, or frequent maintenance will be needed by a qualified person to sweep the roof clear of debris.

Cedar needs to breathe, and allowing leaves, pine needles and other materials to build up on the roof is not advised. Sealants and debris both lock in moisture that would otherwise naturally evaporate during normal weather conditions.

The roof should be properly ventilated using a guideline of total net free ventilation area to the area of the attic should be not less than 1:150 or 1:300 if split equally between the attic and the eave. Gutters and downspouts need to be kept clean in order to prevent clogging. A downspout should not be allowed to drain directly onto a roof surface below. Instead, the flow of water should be directed away from the building.

The life of a cedar roof depends upon the amount of maintenance performed. All roofing materials need periodic maintenance checks and repairs. Cedar roof maintenance should be performed by professional inspectors familiar with safety precautions, generally at least twice a year, or after major storms, so that any damage can be repaired or built up debris removed.

Typically, the ridge cap used at peaks and hips (where two sloping sides of the roof meet at areas which are not the apex of the structure) on a roof will require replacement first, as this area takes the brunt of any weather system affecting the structure. The roof should also be checked for loose fasteners, split product where felt is exposed, or damage from hailstorms. With proper preventative maintenance and installation of quality materials, a heavy handsplit and resawn cedar roof can last 50 years or more. Identifying the difference in naturally weathered and storm damaged cedar roofs is sometimes a difficult task. It takes a trained eye to assess a cedar roof and determine if it is in fact damaged due to hail, or if it is just naturally weathered. It also takes a trained eye to determine the amount of repair required. Use appropriate repair versus replacement methodology (contact the CSSB for more details).

Another benefit to using cedar shakes and shingles is that repairs can be made readily only to those roof sections that need it, rather than tearing off the entire roof after storm damage.

If an enhanced lifespan is of critical importance, then using a pressure impregnated preservative treated cedar shake or shingle product should be considered. Another option is to nail zinc or copper strips at the ridge for moss control. However, for some roofs, this method is only effective for a few courses underneath the metal strip and this alone should not be considered sufficient to complete the maintenance program. Use of a bleach and water solution to clean surface debris and halt the growth of lichens and moss is another option. The United States Department of Agriculture (USDA) Forest Product Laboratory in Madison, Wisconsin is an excellent source of information. (www.fpl.fs.fed.us/)

Pressure or Power Washing

Pressure or power washing in the roofing industry refers to a machine-driven, high velocity stream of water being directed at the surface below, conducted from the water source via a wand held by a human operator.

When weighing the benefits and drawbacks of using pressure washer machines on a cedar roof, several factors should be considered, including the experience of the person performing the work, the age and condition of the roof, the pressure per square inch, spray tip, distance from the roof, and washing technique. Pressure washing equipment, when placed in the hands of an inexperienced person, can cause significant damage to a roof. When used properly, pressure washers can be effective in removing surface debris. It is critical to clean from the top down, using proper technique, in order not to blow water up into the attic area. An inspection of the roof first should be performed to note any shakes or shingles in need of replacement.

Topical sprays can be considered for preservative reasons. These sprays are not a replacement for the pressure impregnation treatment that is available from the factory prior to the roof being installed. Design professionals who wish to use a topical treatment product on an untreated roof should be aware of several important guidelines.

Do use a topical treatment product that:

• Offers a Material Safety Data Sheet (MSDS), that lists product ingredients and safety precautions


• Is labeled as a cedar roof treatment product or has a letter from the manufacturer stating that treating cedar roofs is an appropriate use for this product


• Is a water repellent, ultraviolet (UV) inhibitor, and/or U.S. Environmental Protection Agency (EPA) registered wood preservative


• Has a manufacturer's performance guarantee

Do not use a topical treatment product that:

• Makes outrageous claims (such as a 10-year effectiveness)


• Makes fire retardant claims


• Is a sealant, waterproofer or plasticizer


• Contains unfortified linseed oil, diesel fuel or crank case oil

Before considering any treatment or cleaning solution application to a pressure impregnated treated roof, always check with the pressure impregnation treatment company to see if it will affect the treatment warranty.

Industry reference guides include the "New Roof Construction Manual" and "Exterior and Interior Wall Manual," available for free from the CSSB.