How far can a beam span without support?

How Far Can A Beam Span Without Support?

The following table shows the maximum allowable length of a beam without support. The table was created using the data from various sources.

Table 1: Maximum allowable length of a beam without support

Length (ft) Maximum unsupported length (ft) 8 5/16″ 0 9 3/4″ 10″ 11 7/8″ 12″ 13 1/2″ 14″ 15 1/2″ 16 1/2″ 17 3/4″ 18 3/4″ 19 5/8″ 20 5/8″ 21 7/8″ 22 7/8″ 23 9 1/2 ” 24 9 1/2 ” 25 11 ” 26 12 ” 27 13 ” 28 14 ” 29 15 ” 30 16 ” 31 17 2/” 32 18 3/” 33 19 4/” 34 20 5/” 35 21 6/” 36 22 7/” 37 23 8/” 38 24 9 3/4 “

Noted: This table is for lumber that’s at least 1″ thick.

For each additional inch, add 1 foot to the maximum length.

Sources & references used in this article: