In determining the height of a residential chimney above a roof, the top of the flue liners should be at least _____ above a roof ridge or any raised part of a roof within 10 feet of the chimney.

In determining the height of a residential chimney above a roof, the top of the flue liners should be at least _____ above a roof ridge or any raised part of a roof within 10 feet of the chimney.