Page 156 - Masonry and Concrete

Masonry Construction Techniques
155
MASONRY CONSTRUCTION TECHNIQUES

CORNER LEAD

FOOTING

END LEAD

FIGURE 5-16
Corner and end leads on a masonry wall.

checked to assure that it is level in both directions and plumb. A
mason’s level is used as a straightedge to check horizontal alignment.
Units are brought to level and made plumb by light tapping with the
trowel handle. This tapping, plus the weight of the unit and those
above, helps form a good bond at the bed joint. Once the units have
been laid, however, they cannot be adjusted or realigned by tapping
without breaking the mortar bond. If it is necessary to reposition a
unit, all the mortar must be removed and replaced with fresh.
For filling in the wall between leads, a string line is stretched from
end to end and the top outside edge of each unit can then simply be
aligned with the string. Nylon string is wrapped securely around two
wooden line blocks. One line block is hooked on the corner of one lead
so that the string is level with the top of the unit in the course being
laid (Figure 5-19). The string is then stretched to the opposite corner
lead and the other line block is hooked at the same height. The line
blocks are held in place by the tension of the string. Steel line pins can
also be used to run the string line. They are driven into the head joints
of the leads and the string is wrapped around and pulled tightly. The

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