Estimating in Building Construction

Doors and Windows 187

FIGURE 15.2.Window Takeoff.

Aluminum Windows and Curtain Wall. The shapes
for aluminum mullions used in curtain walls or storefronts
are made by an extrusion process and roll forming. Finishes
include mill finish (natural silvery sheen), anodizing (pro-
tective film; it may be clear or a variety of color tones), paint,
lacquer, and colored or opaque coatings. Obviously, the fin-
ish required must be noted, because it will affect the price of
the materials. The specifications will require certain thick-
nesses of metal throughout the construction of the frames.
Care on the job is important, because exposed alu-
minum surfaces may be subject to splashing with plaster,
mortar, or concrete masonry cleaning solutions that often
cause corrosion of the aluminum. Exposed aluminum
should be protected during construction with either a clear
lacquer or a strippable coating. Concealed aluminum that is
in contact with concrete, masonry, or absorbent material
(such as wood or insulation) and may become intermittently
wet must be protected permanently by coating either the
aluminum or the adjacent materials. Coatings commonly
used include bituminous paint and zincchromate primer.

The costs of such protection must be included in and

are part of the cost of the project. If the frames are to be

installed by a subcontractor, the estimator must check to see

whether the subcontractor has included the required protec-

tion in the proposal; if not, the estimator will have to make

an allowance for it. Also, who will apply the protection? If a

strippable coating is used on exposed aluminum, the estima-

tor must note who will remove the coating, whether the sub-

contractor has included this in the price, or whether the

general contractor will handle it. Any piece of work that

must be done costs money, so estimators ensure that all

items are included.

Before the job is bid, the estimator should check the

details showing how the windows are to be installed. They

may have to be installed as the construction progresses

(where the window is built into the wall), or they may be

slipped into openings after the building has been con-

structed. The method is important as there is always a time

lag for approvals, and manufacture (of custom units) and

coordination will be important.

Labor Hours

Windows per Window

Wood

In Wood Frames 2.0 to 3.5

In Masonry 2.5 to 5.0

Metal

In Wood Frames 2.0 to 3.5

In Masonry 2.0 to 4.0

Over 12 s.f. Add 20%

Bow and Bay Windows 2.5 to 4.0

EXAMPLE 15-1 RESIDENTIAL WINDOWS

Determine the quantity of windows for the residence found in
Appendix B. The window schedule (Figure 15.1) typically denotes
all window sizes and types. The estimator simply must verify the list
and count the number of each size and type (Figure 15.2).

FIGURE 15.1.Sample Window Schedule.

Installation:

6 wood windows in masonry

Productivity rate (Figure 15.3) 3 labor hours / window

Labor cost ($)18 hours$12.25 per hour$220.50

18 labor hours

Labor hours6 windows3 labor hours per window

EXAMPLE 15-2 COMMERCIAL BUILDING

Determine the quantity of windows in the small commercial build-
ing found in Appendix A. Figure 15.4 is an excerpt of the window
schedule for that project.

Single hung 3 0  7  0 count 2

Fixed glass 3 0  7  0 count 17

Productivity rate (Figure 15.3) 3 labor hours / window

Labor cost ($)57 hours$12.25 per hour$698.25

57 labor hours

Labor hours19 windows3 labor hours per window

FIGURE 15.3. Labor Hour Productivity

Rates.