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How to Lay Out Posts for an Octagon Gazebo

Amelia Allonsy

Building a gazebo adds a focal point and gathering area to your garden. Gazebos come in various shapes, including squares, hexagons and octagons. Octagonal gazebos provide the look of a round gazebo, but are easier to construct because they have eight flat sides. Octagonal gazebos require eight posts to support the structure. Laying out the posts requires careful measurements to ensure the finished structure is symmetrical. Getting the angles precise may seem difficult, but if the octagon shape is thought of in terms of two squares, the task is much easier.

Laying out posts for an octagonal gazebo requires careful precision to achieve symmetry.

Step 1

Measure and cut four 1-by-4-inch boards to equal lengths, approximately 1 foot shorter than the desired diameter of the gazebo. For a gazebo with a 10-feet diameter, for example, the boards need to be at least 9 feet long.

Step 2

Measure and mark the center point of each board, and drill out a 5/8-inch-diameter hole through the center marks.

Step 3

Mark the center point of the gazebo on level ground and drive a piece of 1/2-inch steel reinforcing bar into the ground at the center point.

Step 4

Slide each of the four boards over the reinforcing bar so that they are stacked together with the reinforcing bar forming a pivot point in the center.

Step 5

Fan out the four boards so they are spaced equally, creating a T-shape with two of the boards and an X-shape with the other two boards. When the boards are fanned out properly, each board should form a 45-degree angle to the neighboring board.

Step 6

Brace each of the boards to hold them in place using small boards, such as lath boards, and C-clamps. Measure the spaces between each of the boards and adjust the braces as necessary to ensure symmetry.

Step 7

Spray paint a 12- to 14-inch circle to mark the space for each post hole, using the board frame as the guide. The holes might begin at the end of each board or set back a few inches from the end depending on the desired diameter for the gazebo; however, the positioning must be the same for each of the eight post holes to achieve symmetry.