In-Ground Flagpole Installation

Long before fiberglass or extruded aluminum, craftsmen working in spar yards used lathes to turn wooden flagpoles—masts with landlubber destinies. Honoring this tradition, flagpole terminology still twists nautical: Flags are raised by sheaves (pulleys) and halyards (ropes) that are secured on cleats. Some poles even have double or step masts, yardarms (crossbars) and gaffs (extra spars perpendicular to the yardarms).

Although wood is the most historically authentic material for a flagpole, it is also the most expensive. Here are some less costly options:

Fiberglass: The best fiberglass poles have a UV-resistant finish and are constructed with the majority of fibers running vertically; fibers that run horizontally make the pole weaker and can cause failure. Fiberglass poles are available in various colors and are light, easy to install and maintenance-free. The rigging can be run inside the pole to eliminate the sound of slapping halyards. Most models do not make lowering easy, however.

Standard Aluminum: Although light, easy to install and available with internal rigging—no halyards to clang against metal—some painted aluminum poles chip, leaving uncoated spots that may stain. The most durable finish is clear-coated brushed metal, which often looks incongruous against a white clapboard house.

Telescoping Aluminum: The sight of retracting buttons and joints may not enhance the elegance of a pole’s silhouette, but telescoping models are easily portable. Putting them up or taking them down requires only a few minutes.

How to Install a Residential In-Ground Flagpole

1. Choose a Location and Pole Height

• To install a flagpole, the first step is deciding where in the yard to put it. You can do this by assembling a mock-up with PVC pipe and couplers. One person should hold up the pole in various spots so a second person can judge the effect from afar. A grassy spot in a prominent place by the front door of the house is ideal.
• To choose a pole’s height, consider the height of the house or building: 18 to 25 feet for single story building, 25 to 30 feet for two stories, and 30 to 40 feet for three stories.

For this project, This Old House master carpenter Norm Abram installed a pole with a linchpin assembly, which allows the pole to be lowered easily for painting or major storms.

2. Dig a Foundation for the Anchor

• The day before installation, dig a foundation hole 30 inches deep and 24 inches in diameter, using a post-hole digger and shovel. This will hold the painted steel anchor, which supports the pole and prevents ground moisture from wicking up and rotting the wood.
• For soil that doesn’t drain well, add 6 inches of gravel or crushed rock before pouring the concrete. The base should be high enough that the pole can swing up and down with ease.
• Shovel in 6 inches of concrete, let it set for a few minutes, and drop in the anchor.
• Check the anchor’s alignment using an 18-inch bubble level, then fill the hole with concrete and trowel it smooth.

3. Drill Holes for the Pivot Bolt

• After the concrete has set for 24 hours, rest the pole on two padded sawhorses.
• In order to center the cleat on the pole’s halyard side, measure 42 inches from the bottom.
• Using an 11/16-inch bit, drill holes for two ⅝-inch bolts.

4. Attach the Finial

• To affix the truck (the flanged top that holds the finial and through which the halyards are threaded), set the double sheave into a notch on the top of the pole, so a sheave with the halyard pulled through lines up with a cleat on the base.
• Before screwing on the truck, coat the inside and edges with silicone caulking for a watertight seal.
• Fit the finial into a ½-inch threaded hole in the center of the truck.

5. Install the Pole

• Set the pole into the anchor and insert the pivot bolt. Adjust the pole until it is plumb, checking how it looks from afar as a helper holds it steady.
• Holding the preferred position, mark the pole at the predrilled holes on the anchor. Remove the pole, rest it on the padded sawhorses, and drill holes for the locking bolt.
• Insert the pole into the anchor again and install the pivot bolt.
• Finally, install the locking bolt and finger tighten it. Once again, check to make sure the pole is plumb.

Tools