The Hail Stones

• Tests performed by Penn State University suggest that about 30 percent of cedar shingles are damaged when struck by a 1 1/4-inch hailstone while hailstones 2 inches in diameter will damage all of the cedar shingles on the roof. The heavier cedar shake deals with hail better than shingles. About half of the shakes are damaged by hailstones 1 1/2 inches in diameter while the 2-inch hailstones still damage 100 percent of the roofing material.
  
  

Age of the Shingles

• Older shingles have less strength and are more prone to damage by hailstones, which is compounded by any moss growth on the cedar shingles or decay from high moisture content on shaded portions of the roof. Cleaning and treating the shingles reduces the likelihood of damage from hail.
  
  

Number of Damaged Shingles

• Whether to replace or repair wood shingles often boils down to a numbers game. If the roof requires repairs to more than 30 shingles in a 100-square foot area, look at replacing all the shingles. When fewer shingles are damaged, replace them if the roof is older and the shingles are brittle. Working on the brittle shingles will cause breakage, compounding the problem caused by the hail.
  
  

Leaks

• If the roof leaks, replacement may be the only option. Wood shingles are placed with the seams between shingles staggered. If the hail stone breaks a shingle directly above the seam of the shingle below, water can leak directly into the home. Make any roof repairs, and stop the leak before making repairs to the interior of the building caused by the water damage.