Some Cedar Roof Facts
Similar to all roof types today, cedar roofs are under attack from elements unknown in the recent past. Acid rain and hardy new strains of blue-green algae (cyanobacteria), adapted to less humid environments like New England, are invading our roofs and home exteriors. As an organic material, cedar is particularly prone to conditions of weather and plant infestations and must be maintained. Moisture retention and intense exposure to the sun are a cedar roof’s two worst enemies.
When first installed cedar shakes and singles retain the benefits they once had in the living tree, and if maintained, will last a normal lifespan of 40 – 60 years. Cedar’s first line of defense against moisture, decay and insect damage are its natural oils and resins. Cedar has a natural oil content of 3% when new. As time goes by, these essential oils leech and bake out due to the sun, wind, and rain, and must be replaced.
A cedar roof needs to breathe and stay dry…As a natural cellular material, cedar is “hygroscopic”, which means it needs to absorb and discharge moisture and remain at equilibrium with its surrounding atmosphere in order to function efficiently as a roofing product. A cedar roof that dries after wetting will last much longer than one that stays damp.
Cedar needs to be dry…but not dried out…Oils lost to weathering are important to cedar roofs in a number of ways.
- Oils and resins are responsible for cedar’s resistance to pests and decay.
- Oils retard water absorption at the cellular level, enabling shakes and singles to shed water quickly and dry out faster.
- Oils supply the dimensional stability and resilience needed by each shake and shingle to defend against cracking and splitting as they move around due to normal expansion and contraction, especially significant during the freeze/thaw cycles of our cold New England winters.
- Oils provide buoyancy, which prevents breaking and brittleness due to drying out and aging.
- Oils give new shingles and shakes the natural honey and cinnamon tones they are known for, and mature cedar roofs their classic and distinguished silvery-gray look.