Q: I have noticed that many arches use special tapered brick. Can an arch be made with standard brick units?
A: The tapered or wedge shape provides a very attractive appearance, with relatively uniform mortar thickness along the length of the arch. Very tight radius arches can be made with tall tapered brick units. However, in most cases, standard uncut bricks are used for arches. When standard bricks are used, the variation in thickness occurs in the mortar joint, rather than in the unit itself.
The Brick Industry Association in Technical Note 31, Table 1, provides a minimum radius for uncut arch brick, which is dependant on the nominal face dimension.
The minimum permissible radius for an arch created using nominal 8-inch-long brick is 6.7 feet.