Brick Joint-Perp Joint - Perp joint can also be known as perpend, p. joint, head joint or cross-j.
The perp joint is the vertical mortar joint between bricks or blocks laid on the same course. These are more difficult to fill than bed joints (see Brick Joint-Bed Joint') and are therefore weaker.
Once the bed joint has been spread evenly, the perp/head joint is spread on to the header of the brick/block and placed down on to the perp joint. It is important to 'keep the perp ends' (ensure that alternating courses are inline) and make sure that buttering gives a joint well filled with cement to prevent penetration by driving rain.
Below is a 3D image that shows Brick Joint-Perp Joint. You can move the 3D object around with your mouse.
