No asphalt shingle roof should be less steep than 3 in 12. If the roof has a normal slope, check the underlayment if possible. Low-slope roofs should have at least two such felt layers. Wood shingles or shakes This type of covering has a normal life expectancy of 25 to 30 years in climates that are not excessively hot and humid, but durability varies according to wood species, thickness, the slope of the roof, whether shingles are made of heartwood, and whether they have been periodically treated with preservative. Shakes are hand-split on at least one face and either tapered or straight.
Shingles are sawn and tapered.
Check the roof slope. The minimum slope for wood shingles is 3 in 12 and the minimum slope for shakes is 4 in 12. As wood shingles and shakes age, they dry, crack, and curl. In damp locations they rot. Replace them when more than one-third show signs of deterioration.