Tooling block joints, also called "pointing," requires simple hand tools and a steady, practiced hand. Many tooling techniques simply alter the appearance of a block wall's grout line, while other techniques improve the joint's resistance to deterioration. To point concrete block joints, the do-it-yourself mason can use standard brickwork trowels or specialized pointing trowels. Understanding the characteristics of concrete block joints allows you to choose a pointing technique according to the desired appearance and lifespan of the wall.
Flush mortar joints are precisely even with the surfaces of adjacent blocks. In other words, the blocks and mortar joints create a single, level plane. Flush joints are relatively easy to create. To point a flush mortar joint, masons either draw the flat edge of trowel along the joint's wet mortar or draw a straight edge, such as a straight-sided piece of lumber, along the the joint. If properly pointed, flush joints are moderately weatherproof.
Like the flush joint, the raked joint sits on a parallel plane relative to its surrounding surfaces. However, unlike the flush joint, the raked joint is not level with the surrounding blocks, but recessed toward the wall's interior. Therefore, the top of the block below the joint forms a tiny shelf at the joint's bottom. This tiny shelf tends to gather and hold water, making the raked joint susceptible to deterioration. However, the recessed raked joint creates an attractive visual impression of depth.
As suggested by its name, the concave joint curves toward the interior of the wall. Masons typically use a special pointing trowel to create this joint. The trowel's blade is shaped like a half-cylinder and fits precisely within a mortar joint. After drawing the trowel through the joint, the mortar resembles a smooth half-pipe. Because the concave joint slopes outward at its bottom, it tends to shed water and resist deterioration.
Like the concave joint, the V joint slopes inward from both top and bottom. However, unlike the concave joint, the V joint is formed by two sharp angles that, from a profile view, resemble a sideways letter V. Masons use a special trowel, called a V pointing trowel, to create this joint. Because of its sharp downward angle, the V joint sheds water well and resists deterioration.
The weathered joint forms a single slope downward and outward from the joint's top. This single slope forces water away from the joint and provides the mortar protection from deterioration. However, creating a consistently level weathered joint across an entire wall requires concentration and practice. Masons use a square pointing trowel turned on its side to create a weathered joint.
- Photo Credit block wall image by Irina Kodentseva from Fotolia.com
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