Shingles are individual overlapping elements forming the outer layer of a roof, shedding water and protecting the building from weather. Asphalt shingles are most common in Canadian residential construction due to affordability and reasonable durability. Other materials include wood shakes, slate, tile, and metal shingles. Shingles are installed in overlapping rows starting at the bottom edge, so water flows over each layer to the next. Building codes specify requirements for shingle materials, installation methods, and fire ratings. Shingle lifespan varies by material—asphalt typically lasts 20-30 years, while slate or metal can last 50+ years. Roof replacement is a significant homeowner expense.