Page 317 - Masonry and Concrete

Masonry Garden Walls

316 CHAPTER NINE

sufficient strength to withstand the weight
of the wall without uneven settlement. If
the soil under the footing is soft or unstable,
or if the area is not well drained, a 6–8-in.
layer of compacted gravel should be placed
in the bottom of the footing excavation. If
1 /2 W
W 1 /2 W
the ground slopes substantially along the
length of the wall, both the concrete footing
and the wall may have to be stepped to fol-
low the slope. For flatter slopes, build a
footing that is deep enough so that its bot-
tom is below the frost line but at the same
elevation for the full length of the wall.
W
Refer to Chapter 6 for details on concrete
footings.
Industry rules of thumb recommend
2 W that the footing thickness should be the
same as the width of the wall it supports,
and the footing width should be a mini-
FIGURE 9-1
mum of two times the thickness of the wall
Rule-of-thumb proportions for masonry garden wall it supports (Figure 9-1). For an 8-in.-thick
and screen wall footings.
wall, this would mean a 16-in.-wide foot-
ing, 8 in. thick. Minimum concrete strength should be 2,500 psi. Form-
work should be constructed in the same way as formwork for
foundation wall footings. Where piers or pilasters are incorporated into
the design of a wall, the footing must be wider as well (Figure 9-2).

9.2 Brick Garden Walls

Brick walls can be built in many sizes, shapes, and styles. The most
common type of brick garden wall is a double-wythe wall with a fin-
ished thickness of about 8 in. Most building codes require that for lat-
eral stability, maximum wall height should not exceed 18 times the
wall thickness. An 8-in. wall can be a maximum of 12 ft. high (18
8 in. 144 in. 12 ft.). In most instances, residential walls will not
exceed 6 or 8 ft., and some building codes and subdivision ordinances
restrict wall heights to 6 ft.

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