Estimating in Building Construction

154 CHAPTER THIRTEEN

Purchase Quantity

Size Length (lf ) Pieces

2  10 10 10



Bridgingis customarily used with joists (except for glued
nailed systems) and must be included in the costs. Codes and
specifications vary on the amount of bridging required, but
at least one row of cross-bridging is required between the
joists. The bridging may be wood, 1 3s or 1 4s, metal
bridging, or solid bridging (Figure 13.20). The wood bridg-
ing must be cut, while the metal bridging is obtained ready
for installation and requiring only one nail at each end, half
as many nails as would be needed with the wood bridging. I-
joist required solid bridging with I-joist material.
In this estimate, the specifications require metal
bridging with a maximum spacing of 8 feet between
bridging or bridging and bearing. A check of the joists’
lengths shows that they are approximately 12 feet long
and that one row of bridging will be required for each row
of joists.
Because each space requires two pieces of metal bridg-
ing, determine the amount required by multiplying the
joistspaces(not the number of joists) times two (two pieces
each space) times the number of rows of bridging required.

bf 10 

2 –  10 –

12

 10 ¿167 bf

FIGURE 13.20.Bridging.

EXAMPLE 13-7 METAL BRIDGING



Sheathing/deckingis taken off next. This sheathing is most

commonly plywood or waferboard. First, a careful check of

the specifications should provide the sheathing informa-

tion required. The thickness of sheathing required may be

given in the specifications or drawings (Figure 13.4). In

addition, the specifications will spell out any special instal-

lation requirements, such as the glue-nailed system. The

sheathing is most accurately estimated by doing a sketch of

the area to be covered and by planning the sheathing lay-

out. Using 4 8 sheets, a layout for the residence is shown

in Figure 13.21.

Another commonly used method of estimating sheath-

ing is to determine the square footage to be covered and

divide the total square footage to be covered by the area of

one sheet of sheathing (Example 13-8). Although both

methods give almost the same answer, the use of square feet

alone does not allow planning of sheet layout on irregular

plans and does not allow properly for waste. This is particu-

larly true when using tongue and groove sheathing where

waste without the proper tongue or groove cannot be used

even if it is of a usable size. List the quantity of sheathing

required on the workup sheet, being certain to list all related

information.

152 pieces

Metal Bridging38 spaces2 pieces per space2 bays

38 spaces between joists (refer to Example 13-4)