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Flagpole Foundation Dimensions

Ground Set or Shoe Base

Ground Set

Ground Set installations are the strongest and most common type of flagpole installation. They require burial of the flagpole shaft in a concrete foundation to a depth equal to 10% of the mounting height.

Ground Set Flagpole Foundation Illustration

NAAMM's Metal Flagpole Manual offers basic suggestions on foundation measurements in firm, dry soil only using dry tamped sand and 3000 PSI concrete. Soil conditions vary by site. Exact foundation requirements should be verified by a Structural Engineer with knowledge of soil conditions in your locality.

Foundation Dimensions
Flagpole
Height
A B C D
20'-0" 2'-0" 2'-6" 30" 24"
25'-0" 2'-6" 3'-0" 36" 24"
30'-0" 3'-0" 3'-6" 36" 24"
35'-0" 3'-6" 4'-0" 36" 30"
40'-0" 4'-0" 4'-6" 45" 36"
45'-0" 4'-6" 5'-0" 45" 36"
50'-0" 5'-0" 5'-6" 50" 42"
60'-0" 6'-0" 6'-6" 60" 48"
70'-0" 7'-0" 7'-6" 60" 48"
80'-0" 8'-0" 8'-6" 72" 48"

Shoe Base

Shoe Base installations are typically used when an above ground installation is required.

Shoe Base Flagpole Foundation Illustration

All 20' to 80' flagpoles with a 4"+ butt diameter can be provided in a shoe base installation option.

Foundation Dimensions
Flagpole
Butt Dia.
AA Base Square BB Base Height CC Bolt Projection Bolt Diameter Bolt Circle Diameter
4" 7-1/2" 3" 2" 3/4" 6-1/2" - 8"
5" 7-1/2" 3" 2" 3/4" 7-1/2" - 8"
6" 9-3/4" 3-1/2" 2-3/4" 1" 9" - 10"
7" 10-1/2" 3-11/16" 2-3/4" 1" 10" - 11"
8" 11-1/4" 3-15/16" 2-3/4" 1" 11" - 12"
10" (Up to .250" Wall) 14" 4-7/8" 3-1/4" 1" 14" - 15"
10" (.312" Wall & Larger) 14" 4-7/8" 3-1/4" 1-1/4" 14" - 15"
12" 7-1/2" 3" 2" 3/4" 16" - 18"
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