Figure 8-47.-Joint finishes.
at the bottom of the arch than at its top, but it should
not narrow to less than 1/4 inch at any point. As
laying progresses, make sure the arch does not bulge
out of position.
It is obviously impossible to construct an arch
without support from underneath. These temporary
wooden supports must not only be able to support the
masonry during construction but also provide the
geometry necessary for the proper construction and
appearance of the arch.
Such supports are called
DIMENSIONS. Construct a brick arch over the
templet (figure 8-49) that remains in place until the
Figure 8-48.-Common arch shapes.
mortar sets. You can obtain the templet dimensions
from the construction drawings. For arches spanning
up to 6 feet, use 3/4-inch plywood to make the
templet. Cut two pieces to the proper curvature, and
nail them to 2-by-4 spacers that provide a surface
wide enough to support the brick.
POSITIONING. Use wedges to hold the
templet in position until the mortar hardens enough to
make the arch self-supporting. Then drive out the
Lay out the arch carefully so that you dont have
to cut any bricks. Use an odd number of bricks so that
the key, or middle, brick falls into place at the exact
arch center, or crown. The key, or middle, brick is the
last one laid. To determine how many bricks an arch
requires, lay the templet on its side on level ground
and set a trial number of bricks around the curve.
Adjust the number of bricks and the joint spacing (not
less than 1/4-inch) until the key brick is at the exact
center of the curve. Then, mark the positions of the
bricks on the templet and use them as a guide when
laying the brick.
Figure 8-49.-Using a template to construct an arch.