TM 5-809-3/NAVFAC DM-2.9/AFM 88-3, Chap. 3
(e) Since the top of the lintel is the top of the wall, the top face compression region of the lintel
must be given lateral support. The maximum distance between points of lateral support, lc, is determined as
1c = 32(b) = 32(7.62) = 244 in = 20.33 ft
(4) Summary. The 8-inch by 24-inch CMU lintel with 2-#4 bars top and bottom and 1-#3 @ 8" o.c.
shear reinforcement located as shown in figure 8-10 is sufficient. The top of the lintel must be laterally
supported at a maximum spacing of 20 feet.