Triangular arch

In architecture, a triangular arch typically defines an arch where the intrados (inner surface of an arch) consists of two straight segments formed by two stone slabs leaning against each other. In this roof-like arrangement, mitre joint is usually used at the crown, thus the arch was in the past also called a mitre arch. Brick builders would call triangular any arch with straight inclined sides. Mayan corbel arches are also sometimes called triangular due to their shape.

Since the sides of a triangular arch are experiencing bending stress, it is a false arch in a structural sense (historically preceding the invention of true arches and going back to Neolithic times ). The design was common in Anglo-Saxon England until the late 11th century (St Mary Goslany).