Estimating in Building Construction

176 CHAPTER FOURTEEN

FIGURE 14.2.Materials Required for Membrane Waterproofing per Square.

the cost is greater for vertical surfaces than for horizontal
surfaces, and there is generally less working space on the
vertical.
The square footage of protective coating must also be
determined; this is the same as the area to be waterproofed.
The type of protective coating, thickness, and method of
installation are included in the specifications.
The sprayed-on asphalt and chopped fiberglass require
special equipment to apply, and most manufacturers specify
that only if these are applied by approved applicators will
they be responsible for the results. Materials required per
square are 8 to 10 gallons of asphalt and 7 to 10 pounds of
fiberglass. The surface that is being sprayed must be clean
and dry.

Labor. Membrane waterproofing is almost always
installed by a subcontractor (usually a roofing subcontrac-
tor). A typical subcontractor’s bid (to the contractor) is
shown in Figure 14.3. Typical labor productivity rates are
shown in Figure 14.4.

14–3 Integral Method

The admixtures added to the cement, sand, and gravel gener-

ally are based on oil-/water-repellent preparations. Calcium

chloride solutions and other chemical mixtures are used for

liquid admixtures, and stearic acid is used for powdered

admixtures. These admixtures are added in conformance

with manufacturers’ recommendations. Most of these

admixtures enhance the water resistance of the concrete, but

offer no additional resistance to water pressure.

Estimating. The amount to be added to the mix varies

considerably, depending on the manufacturer and composi-

tion of the admixture. The powdered admixtures should be

mixed with water before they are introduced into the mix.

FIGURE 14.3.Subcontractor’s Bid for Membrane
Waterproofing.

FIGURE 14.4.Labor Hours Required for Applying

Waterproofing and Dampproofing.

Labor Hours per

Type of Work 100 s.f.

Cleaning 0.25 to 3.5

Painting Brush, per Coat 0.5 to 2.0

Parging, per Coat 1.0 to 2.5

Metallic 1.5 to 3.0

Waterproofing

Asphalt of Tar, per Coat 0.7 to 2.0

Felt or Reinforced, per Layer 1.2 to 2.5

FIGURE 14.1.Membrane Waterproofing.