Estimating in Building Construction

Thermal and Moisture Protection 177

Liquid admixtures may be measured and added directly,
which is a little less trouble. The costs involved derive from
delivering the admixture to the job site, moving it into a con-
venient place for use, and adding it to the mix. The contain-
ers may have to be protected from the weather, particularly
the dry admixture containers.

14–4 Metallic Method

Metallic waterproofing employs a compound that consists
of graded fine-iron aggregate combined with oxidizing
agents. The principle involved is that, when the compound
is properly applied, it provides the surface with a coating of
iron that fills the capillary pores of the concrete or masonry
and, as the iron particles oxidize, the compound creates an
expanding action that fills the voids in the surface and
becomes an integral part of the mass. Always apply in
accordance with the manufacturer’s specifications, and
always apply the compound to the inside of the wall.

Estimating. The estimator needs to check the specifica-
tion for the type of compound to be used and the thickness
and method of application specified. From the drawings, he or
she can determine the square footage to be covered and, using
the manufacturer’s information regarding square feet cover-
age per gallon, determine the number of gallons required.
Labor will depend on the consistency of the compound,
the thickness, and the method of application required as well
as the convenience afforded by the working space. Equip-
ment includes scaffolds, planks, ladders, mixing pails, and
trowels.

14–5 Dampproofing

Dampproofing is designed to resist dampness and is used
on foundation walls below grade and exposed exterior
walls above grade. It is not intended to resist water pres-
sure. The methods used to dampproof include painting the
wall with bituminous materials below grade and transpar-
ent coatings above grade.Pargingwith a rich cement base
mixture is also used below grade, often with a bituminous
coating over it.

14–6 Painting Method

Among the most popular paints or compounds applied by

brush or spray are tar, asphalt, cement washes, and silicone-

based products. This type of dampproofing may be applied

with a brush or mop, or may be sprayed on. The type of

application and the number and thickness of coats required

will be determined by the specifications and manufacturer’s

recommendations.

Below grade on masonry or concrete, the dampproofing

material is often black mastic coating that is applied to the

exterior of the foundation. It is applied with a brush, mop, or

spray. The walls must be thoroughly coated with the mastic,

filling all voids or holes. The various types available require

from one to four coats to do the job, and the square footage

per gallon varies from 30 to 100. The more porous the sur-

face, the more material it will require.

Transparent dampproofing of exterior masonry walls is

used to make them water repellent. The colorless liquids

must be applied in a quantity sufficient to completely seal the

surface. Generally, one or two coats are required by the man-

ufacturers, with the square footage per gallon ranging from

50 to 200.

Estimating Painting. To estimate these types of damp-

proofing, it is necessary first to determine the types of

dampproofing required, the number of coats specified (or

recommended by the manufacturer), and the approximate

number of square feet that one gallon of material will cover

so that the amount of material required may be determined.

If two coats are required, twice the material is indicated.

The amount of labor required to do the work varies

with the type of compound being used, the number of

coats, the height of work, and the method of application.

When the surface to be dampproofed is foundation walls

below grade and the work is in close quarters, it will proba-

bly take a little longer. Sprayed-on applications require

much fewer labor hours but more expensive equipment.

High buildings require scaffolds that will represent an

added cost factor.

Equipment that may be required includes ladders,

planks, mixing cans, brushes, mops, spraying equipment,

and scaffolding.

EXAMPLE 14-1 FOUNDATION WALLS

The below-grade foundation wall on the building in Appendix A
must be brushed with a bituminous product on the 8 4 -high
foundation walls to within 2 inches of the finished grade.
Figure 14.5 shows the building layout, and Figure 14.6 is a tabula-
tion of the linear feet of the foundation wall. The coverage rate is
60 sf per gallon.

Area to be dampproofed112.67¿8.167¿920 sf

Area to be dampproofed 112 ¿ 8 –  8 ¿ 2 –

Assume the height to be sprayed is 8¿ 2 –

Using the labor productivity rates from Figure 14.4 and a local

prevailing wage rate of $13.25 per hour, the labor costs can be

determined.

Labor cost 11.5 hour$13.25 per hour$152

Labor costLabor hoursWage rate

11.5 labor hours

Labor hours 1.25 labor hours per sq9.2 squares

Use 16 gallons

Gallons of asphalt 920 sf> 60 sf per gallon 15.3 gallons