Which type of roof is known for being flat and is commonly used in urban buildings?

The type of roof known for being flat and commonly used in urban buildings is the flat roof. Flat roofs are typically constructed with a slight slope to allow for water drainage, while their horizontal design maximizes usable space. This characteristic makes flat roofs particularly appealing in urban areas, where space is often limited, allowing for the potential of rooftop gardens, additional HVAC equipment, or even leisure spaces.

Moreover, flat roofs are generally easier and safer to access for maintenance and repairs compared to other roof types. They are often constructed with materials designed to withstand pooling water, which is essential in maintaining the roof's integrity over time. This design not only suits the architectural style of many modern urban buildings but also aligns with functionality demands in densely populated areas.

Alternative roof types, such as pitched roofs or gable roofs, are less common in urban settings due to their design requirements and space inefficiencies. They typically present complications when it comes to utilizing rooftop space effectively. Curved roofs, while aesthetically unique, are also not as practicality-driven as flat roofs in the context of urban infrastructure.