Page 235 - Masonry and Concrete

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

Waterproofing membranes must be fully adhered to the wall so
that water cannot flow behind the membrane, and so that any leaks
which occur will be easier to trace to the source. Membranes applied
to concrete or concrete block must have sufficient flexibility to span
cracks which will inevitably appear as a result of curing shrinkage,
and enough elasticity to expand and contract with temperature
changes. Steel reinforcement or control joints can be used to limit the
amount of shrinkage cracking which will occur and to regulate the
location of such cracks. If control joints are used, they must be sealed
against water intrusion with an elastomeric sealant that will not
deteriorate when submersed in water, that is chemically compatible
with any membrane waterproofing or dampproofing which will be
applied, and is resistant to any contaminants which may be present
in the soil.
The CABO One and Two Family Dwelling Code requires water-
proofing of foundation walls enclosing habitable space or storage from
the top of the footing to the finish grade in areas where a high water
table or other severe soil-water conditions are known to exist. Damp-
proof coatings are required in all other conditions. Waterproofing may
consist of one of the following:

■ 2-ply hot-mopped felts

■ 55-pound roll roofing
■ 6-mil polyvinyl chloride
■ 6-mil polyethylene

■ 40-mil polymer-modified asphalt

The joints in the membranes must be lapped and sealed with an adhe-
sive compatible with the membrane itself. Dampproofing for masonry
3
walls may consist of a 8-in. portland cement parging covered with
one of the following:

■ bituminous coating
■ 3 pounds per square yard of acrylic modified cement

■ 1/8-in. coat of surface bonding mortar, or
■ any material permitted for waterproofing.

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