Estimating in Building Construction

Concrete 113

EXAMPLE 10-17 FOUNDATION WALL FORMS

Determine the labor costs associated with placing the 3 8 -high
foundation wall form from the sample project found in Appendix
A. From Example 10-5 and Figure 10.9, the quantity of formwork
can easily be found. From that example, there are 303 0 of 3 8 -
high foundation wall. The contact area is found by multiplying
these two dimensions and then by doubling that quantity to com-
pensate for both sides being formed.

The time required for forms has been estimated from Figure 10.31.
The hourly wages are based on local labor and union conditions.
Assuming that the forms will be used twice, the following calcula-
tion can be performed.

Labor cost$8,241 .50 

Labor cost622 hours$13 .25 per hour

Labor costLabor hoursWage rate

622 labor hours

Labor hours2,222 SFCA0 .28 labor hours per SFCA

Labor hoursQuantityProductivity rate

Contact area (SFCA) 303 ¿3 .667¿2 sides2,222 SFCA

Contact area (SFCA) 303 ¿ 0 –  3 ¿ 8 – 2 sides

Contact area (SFCA)Length (ft)Width (ft)Sides formed

10–10 Form Liners

The type of liner used with the form will determine the tex-

ture or pattern obtained on the surface of the concrete.

Depending on the specified finish, formed concrete surfaces

requiring little or no additional treatment can be easily

obtained. A variety of patterns and textures may be produced

by using various materials as liners. Fiberglass liners, plastic-

coated plywood, and steel are among the most commonly

used. Textures such as wood grain, rough sawn wood, corru-

gations (of various sizes and shapes), and all types of special-

ized designs are available. They have liners that will leave a

finish resembling sandblast, acid etch, and bush hammered, as

well as others. These textures may be used on floors or walls.

Liners are also used to form waffle slabs and tee beam

floor systems; they may be fiberglass, steel, or fiber core.

When liners of this type are used, the amount of void must

be known so that the quantity of concrete may be deter-

mined. This information is given in Figure 10.33. Complete

information should be obtained from whichever company

that supplies the forms for a particular project.

Form liners are often available on a rental or purchase

arrangement; specially made form liners of a particular design

may have to be purchased. When special designs are required,

be certain to get a firm proposal from a manufacturer.

Specifications. Check the specifications for requirements

concerning textures and patterns, liner materials, thicknesses,

configurations, and any other liners. It is not uncommon for

the specifications to state the type of material from which the

liner must be made. The drawings should be checked for types

of texture, patterns, or other requirements of the form liner.

The form liners required may be already in stock at the manu-

facturer or may need to be special ordered, often requiring

months of work, including shop drawing approvals.

Estimating. Estimators take off the square footage of the

surface requiring a particular type of liner and decide how

many liners can be used effectively on the job—this will be

the total number of square feet of the liner or the number of

Productivity Rate

Application Labor Hours/SFCA

Foundation Wall (Plywood)

1 Use 0.44

2 Use 0.28

3 Use 0.25

4 Use 0.22

Footings

1 Use 0.14

2 Use 0.09

3 Use 0.08

4 Use 0.07

Slab on Grade

1 Use 1.2

2 Use 1.1

3 Use 1.0

4 Use 0.8

Columns

1 Use 0.180

2 Use 0.146

3 Use 0.143

4 Use 0.140

Beams

1 Use .2

2 Use 0.18

3 Use 0.15

4 Use 0.14

FIGURE 10.32.Approximate Quantity of Labor

hours.

FIGURE 10.33.Void Area in Concrete.