Page 233 - Masonry and Concrete

Footings, Foundation Walls, Basements, and Slabs
232 CHAPTER SIX

glove. Cracks and voids such as form tie holes should be patched or filled
before applying the dampproofing. The vapor permeability of the interior
coating of a dampproofed concrete or masonry wall should be higher than
the vapor permeability of the exterior coating so that construction mois-
ture and any soil moisture vapor which permeates the wall can evaporate
to the inside (Figure 6-39). Gypsum board and latex paint finishes work
well, but vinyl wallcoverings will trap moisture in the wall.
There are two general methods of waterproofing. In positive side
waterproofing, the waterproofing is applied to the same side of the
wall or floor on which the water source occurs (Figure 6-40a). In neg-
ative side waterproofing, the waterproofing is applied on the opposite
side of the structure as the water source (Figure 6-40b). Positive side
waterproofing is always preferable because the structure itself is pro-
tected from moisture penetration, as well as the interior spaces. This is

HIGHER
VAPOR
PERMEANCE

DAMP
SOIL
MOISTURE

LOWER
VAPOR
PERMEANCE

FIGURE 6-39
Vapor permeance. (from Beall, Christine, Thermal and Moisture Protection Manual,
McGraw-Hill, New York).

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