The trusses I modified in 1983 to accommodate a higher ceiling when I turned a Grade B milk barn into a 3-bedroom house haven't failed yet. The first winter after that project was finished, we had 5 inches of solid ice on the roof after a 36-hour sleet storm. However, I tend to over-build everything from race cars to houses. The original trusses were built from rough-cut oak from a sawmill down the road in the early 1950's. That milk barn went from a 16 X 32 foot concrete block building with a tin roof to a 3,000 square foot 2-story structure after two remodel jobs. The original building is still there- - - -enclosed on all sides by the modifications.
Jerry