(view 4). Make the joints 3/8 inch thick. Then, place
each block in its final position, and push the block
down vertically into the mortar bed and against the
previously laid block.
This ensures a well-tilled
vertical mortar joint (view 5). After laying three or
four blocks, use a masons level as a straightedge to
check correct block alignment (figure 8-8, view 1).
Then, use the level to bring the blocks to proper grade
and plumb by tapping with a trowel handle as shown
in view 2. Always lay out the first course of concrete
masonry carefully and make sure that you properly
align, level, and plumb it. This assures that
succeeding courses and the final wall are both straight
The fourth step is to build up the corners of the
wall, usually four or five courses high. This is also
called laying up a lead. Step back each course
one-half block. For the horizontal joints, apply
mortar only to the tops of the blocks already laid. For
the vertical joints, you can apply mortar either to the
ends of the new block or the end of the block
previously laid, or both, to ensure well-filled joints
(figure 8-9). As you lay each course at the corner,
check the course with a level for alignment
(figure 8-10, view 1), for level (view 2), and for
Figure 8-12.-Checking horizontal block spacing.
plumb (view 3). Carefully check each block with a
level or straightedge to make sure that all the block
faces are in the same plane. This ensures true, straight
walls. A story or course pole, which is a board with
markings 8 inches apart (figure 8-11), helps
accurately place each masonry course. Also check the
horizontal block spacing by placing a level diagonally
across the corners of the blocks (figure 8-12).
When filling in the wall between the corners, first
stretch a masons line along the extensor block edges
from corner to corner for each course. Then lay the
top outside edge of each new block to this line
(figure 8-13). How you grip a block before laying is
Figure 8-11.-Using a story or course pole.
Figure 8-13.-Filling in the wall between corners.