Which roof type has the most plies?

Which roof type has the most plies?

• A. Flat
• B. Gable
• C. Hip
• D. Shed

Answer: (A)

In built-up roofing, plies are the multiple layers of felt and bitumen that make up the membrane. Flat roofs commonly use a built-up system, stacking several plies to create a durable, waterproof surface on a low-slope plane. Depending on climate and performance needs, a flat roof can have three, four, or more plies. By contrast, roofs with a gable, hip, or shed shape are typically covered with a single main layer of shingles or a single-ply membrane, not multiple plies. So, the flat roof is the one that generally has the most plies due to its BUR construction.

In built-up roofing, plies are the multiple layers of felt and bitumen that make up the membrane. Flat roofs commonly use a built-up system, stacking several plies to create a durable, waterproof surface on a low-slope plane. Depending on climate and performance needs, a flat roof can have three, four, or more plies. By contrast, roofs with a gable, hip, or shed shape are typically covered with a single main layer of shingles or a single-ply membrane, not multiple plies. So, the flat roof is the one that generally has the most plies due to its BUR construction.