WHAT IS A FLYING BUTTRESS?
A flying buttress, or arc-boutant, is a specific type of buttress usually found on a religious building such as a cathedral. They are used to transmit the horizontal thrust of a vault across an intervening space (which might be an aisle, chapel or cloister), to a buttress outside the building. The employment of the flying buttress means that the load bearing walls can contain cut-outs, such as for large windows, that would otherwise seriously weaken them. Flying buttresses are often found in Gothic architecture. The purpose of a buttress is to provide horizontal strength to a wall. The majority of the load is carried by the upper part of the buttress, so making the buttress as a semi-arch provides almost the same load bearing capability, yet in a much lighter and cheaper structure. As a result, the buttress seemingly flies through the air, rather than resting on the ground and hence is known as a flying buttress. Though employed by the Romans in early Romanesque work, it was generally
