Wood Roofs: Damage and Repair

Cedar shakes and shingles perform well in hail storms when compared to other products. According to Haag Engineering of Dallas, TX, they have determined that cedar products receive only superficial marring from ¾” (marble size) hail, while composition shingles are bruised, requiring product replacement.

Haag Engineering Hail Characteristics Section 5.3.5

Pea Size Hail – (¼”)

No roof damage.

Marble Size Hail – (¾”)

Minimal roof damage to wood. Composition shingles can be bruised or chipped.

Golfball Size Hail – (1¾”)

Splitting of shakes and shingles begins. Severe damage to composition shingles.

Haag Engineering has defined roof damage as follows:

Once a (composition) shingle has been bruised by hail stones, a progressive deterioration ensues and culminates with a hole in the shingle. A puncture or “bruise” affects the water shedding capability and the long-term serviceability of a roof and, hence, is damage.

Impacting a cedar roof can cause damage if the hail stones are large enough and have sufficient densities, harnesses, and impact velocities to split the wood they strike. If a shingle (or shake) does not split when it is impacted, it is not necessarily damaged.

Further testing of The Clarke Group cedar shakes has shown an even greater durability to hail. The tests conducted at Haag Engineering in January 1995 showed these quality heavy cedar shakes withstood impacts of 2″ hail ice balls traveling at 71 miles per hour.

Haag Engineering also revealed the following from extensive research:

  • Depressions which do not initially cause a split do not create a potential for future splitting.
  • Most depressions disappear with wood fiber recovery and natural weathering.
  • Older but physically sound shingles are no more affected by hail than new shingles.
  • Hail will not affect the natural weathering process of cedar shingles.
  • The opportunity for damage to asphalt shingles is significantly higher than cedar “since large size hail falls only in a small region of the total storm area” according to Haag Engineering.
  • There is no permanent visual damage to cedar when indentations occur. Indentations on wood shakes and shingles will recover and are unnoticeable after several months.
  • If required, repair of cedar roofs is easy after hail damage and the products natural coloring allows perfect matches. Cedar shakes and shingles do not have color coatings with varying color lots, as do virtually all other products.