How To Use Steel I-Beams & Girders
When building a home or an addition it is not necessary to frame the house completely in lumber. Steel beams and girders can be used to span longer distances with less chance of bending than might occur using wood beams. Steel beams are often used in place of heavy wooden girders in the framing of floor systems.
A 6 inch deep steel section can substitute for a wooden girder 14 inches deep, thus saving headroom.
Table 1 gives the allowable loads for steel beams and it indicates two different types of cross sections. The most popular I-beam is designated on the table as an "S" section, as shown in Figure 1. The "S" stands for slim. The "W" designation refers to a steel section with wider flanges, as shown in Figure 2, than the "S" section.
Figure 1 - "S" style I-beam |
Figure 2 - "W" style I-beam |
| Table 1 - Safe Loads In Pounds For Steel I-Beams " Girders | |||||||
Style |
Size |
Span |
|||||
10' |
12' |
14' |
16' |
18' |
20' |
||
S |
6" X 12.5" |
8,700 |
7,300 |
6,200 |
|
|
|
6" X 17.25" |
10,400 |
8,700 |
7,400 |
|
|
|
|
7" X 17.5" |
13,300 |
11,100 |
9,500 |
8,300 |
|
|
|
8" X 18.4" |
17,100 |
14,200 |
12,200 |
10,700 |
9,500 |
8,400 |
|
8" X 23" |
19,300 |
16,100 |
13,800 |
12,000 |
10,700 |
9,600 |
|
W |
8" X 17" |
21,000 |
17,000 |
15,000 |
13,000 |
|
|
10" X 21" |
33,000 |
28,000 |
24,000 |
21,000 |
18,000 |
15,000 |
|
Additional information on beams and girders.