When a building has a combination of frame and bearing walls, it is more accurate to first price the bearing walls with pilasters and bond beams and then price the frame on the basis of the area supported by the frame, or to price the columns and girders separately.
In the following drawing, each wall supports the roof halfway to the posts or columns (as shown by the shaded area) and the balance is supported by the frame.
Area supported by frame: 40' x 80' = 3200 square feet
Total area supported by walls and frame: 60' x 100' = 6000 square feet
Percentage of total supported by frame: 53%
If the frame component used in this example is DI (Fireproofed Steel), select this component and enter 53% for its percentage to indicate that the frame cost for DI is applied to 53% of the total floor area.
If the exact proportion is difficult to determine using the method shown above, the following table can be used. The distances listed are the smallest dimension between bearing walls.
|
Shortest |
Percentage |
Shortest |
Percentage |
|
Distance |
of Floor Area |
Distance |
of Floor Area |
|
30' |
30% |
75' |
60% |
|
40' |
40% |
90' |
70% |
|
50' |
50% |
120' and over |
75% |
For example, the building in the drawing to the left is 60' by 100' without interior walls. Thus the shortest dimension is 60'.
|
From the table: |
50' span, use 50% of full frame cost |
|
|
75' span, use 60% of full frame cost |
|
By interpolation: |
60' span, use 54% of full frame cost |
If there is an interior bearing wall such as shown by the broken line, the shortest dimension is 50', so 50% of the full frame cost is used.