Mortar joints in brickwork take up a considerable large amount of a wall’s surface
area and have a significant influence on the wall’s overall appearance. Some joint
profiles accentuate their individual designs, while others merge the bricks and
mortar to form a flush, homogeneous surface. Mortar joints vary not only by their
appearance, but also by their water-resistance properties.
The following are the most common types of mortar joints:
This popular type of joint is formed in mortar through the use of a curved steel
jointing tool. It is very effective at resisting rain penetration due to its recessed
profile and the tight seal formed by compacted mortar. Patterns are emphasized on
a dense, smooth surface, and small irregularities are hidden.
This type of joint can be made with a V-shaped jointer or a trowel soon after the
bricks are laid. Ornamental and highly visible, the joint conceals small irregularities
and is highly attractive. Like the concave joint, the V-joint is water-resistant
because its formation compacts the mortar and its shape directs water away from
Mortar is recessed increasingly from the bottom to the top of the joint, with the
top end not receding more than 3/8-inch into the wall. The straight, inclined surfaces
of the bed (horizontal) joints tend to catch the light and give the brickwork a
neat, ordered appearance. This joint is less compacted than the concave and V-joints,
although it is still suitable for exterior building walls.
While most popular during America’s Colonial period, this design is often replicated
in newer brickwork. It is created with a grapevine jointer, which is a metal blade
with a raised bead that creates an indented line in the center of the mortar joint.
These lines are often rough and wavy, simulating the generally straight yet slightly
irregular appearance of a grapevine. It is commonly used on matte-finish and antique-finish
Extruded (squeezed) joint
This joint design requires no tooling and is formed naturally as excess mortar is
squeezed out from between the bricks. The result is a rustic, textured appearance.
This design is not recommended for exterior building walls due to the tendency for
exposed mortar to break away, degrading the wall’s appearance.
Raising a rounded, bead-shaped segment of the mortar away from the mortar surface
produces this old-fashioned, formal design. Although beaded joints can create interesting
shadows, they are not recommended for exterior use due to their exposed ledges.
This joint is formed in a similar fashion as the weathered joint, except that the
bottom edge, instead of the top edge, is recessed. It is a very poor insulator against
water, as it will allow water to collect on its bottom ledge.
For this design, mortar is raked out to a consistent depth. Although often left
roughened, it can be compacted for better water-resistance. This design highly emphasizes
the joint and is sometimes used in modern buildings in order to match the historic
appearance of their locales. Unless it is compressed, it is not as water-resistant
as other mortar joints because the design incorporates ledges, which will collect
water as it runs down the wall. Also, when mortar is removed from the joints, it
becomes smeared on the surfaces of the brick at the recesses. To remove the mortar,
contractors often aggressively clean the walls with pressurized water or acid solutions,
which can open up additional voids and increase the possibility of water penetration.
This joint is best used when the wall is intended to be plastered or joints are
to be hidden under paint. Because the mortar is not compressed, it is less water-resistant
than some of the other designs.