Hail Impact Testing of Masonite Shingles

Masonite shingles, aka Woodruff shingles, are wood composite simulated shake shingles that were popular in the mid-1980s to mid-1990s. Woodruff shingles reportedly had good impact resistance when they were new, but due to product defects their actual hail-resistance performance has been questioned. This paper reports on Woodruff shingle field observations after hail events, and hail impact testing performed on aged Woodruff shingles in a laboratory setting. The main body, shiplap edges, and grooved areas of shingles were impacted. Hail stones of varying diameters were launched at Woodruff shingles, and then the impacted shingles were returned to the natural environment and monitored for four years to study the effect, if any, of the hail impacts. The testing conducted showed that hail stones of 1-3/16 inch diameter, or smaller, did not damage the shingle when they struck the main body and groove areas. However, laboratory tests determined that hail stones of 3/4 inch diameter could damage the shiplap edges of the shingles, and field observations confirmed that hail as small as 1/2 inch diameter could potentially damage the same. Also, many in the roofing industry have theorized that hail impact locations that showed no immediate damage to the main body of the shingle could result in accelerated weathering over time. To-date, the hail impacted shingles have been monitored for four years and there have been no signs of accelerated weathering.