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Block-Laying Basics

columns of mortar as it does. Workable mortar can be loaded up on a trowel without flowing off the sides yet yields readily when a brick is pushed into it.

There are two main troweling skills: spreading bed-joint mortar efficiently and buttering (in other words, getting the mortar to stick to vertical and inclined surfaces). With bed joints, the object is to bring as much mud to the wall as possi- ble without dropping it en route. So you first scoop up a full but manageable trowelful of mortar and bring the loaded trowel a few inches above and in line with the units you’re covering (Figure 2, page 5). Then you drop your arm, rotate your wrist, and pull the trowel toward your elbow. With practice, these steps become one fluid motion that leaves a nice line of mortar on the tops of brick or the face shells of blocks.

When buttering, the trick is to keep the mortar from sliding off the trowel. Begin by picking up about half a trowelful of mortar. Hold the trowel so the mortar is facing up, then give the trowel a good hard shake by thrusting it down and pulling it back up sharply. This motion — which flattens the mortar against the trowel so that it stays put when you turn the trowel over — comes in handy when you need to do things like butter the ends of bricks and blocks, apply mortar to the top edges of hollow blocks, or butter the edges of bricks laid in a rowlock pattern.

Work From the Corners

Whenever possible, I design a foundation so that each course can be built with full blocks. Before laying any block, I lay the corner blocks, then snap lines from corner to corner. To main- tain accurate spacing while laying the block, I mark 16-inch centers along the chalk lines (Figure 3, page 6). This helps keep the mortar joints consistently sized and ensures that the last block in each course will fit into place.

I work from inside the wall, with all of my tools and materials set up within the footing perimeter so that I don’t have to reach over the string lines. I set my first pair of corner blocks in mor- tar, aligning their bases with the chalk line and using a spirit level to keep the blocks plumb. Stretched between each pair of corner blocks, a string line helps align the remaining blocks in the course. To set the line, I attach it to a pair of line blocks and hook the line blocks over the corner leads. Tension, created by pulling the line taut, holds the line blocks in place.

As I set in place each of the remaining blocks in the first course, I align its bottom with the chalk line, its top with the mason’s line, and its end with the pencil mark on the concrete. Buttering the ends of both the block I’m laying and the last block laid helps ensure that the mortar joints are fully packed. Orienting the last block in the course so that a flanged end is at

Figure 6. Though partially filled head joints (top) are all too commonly seen in the field, head joints should be completely packed with mortar to pre- vent water intrusion (above). The author butters the end of each brick before setting it, then taps the brick with his trowel to compress the mortar and align the brick with his layout marks, which are marked on the course below.


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