Measure and layout the footings

If you think of an octagon as a square with its corners cut off, you'll realize how simple the shape truly is. A common measurement and trim angle to remember is 22-1/2 degrees. The key, as with any project, is both careful planning and precise measurement.

At a level building site, use batter boards and string to lay out a square twelve feet on each side. To check for 90-degree corners and to find the center of the gazebo, run strings from corner to opposite corner. The square is true and its sides are parallel when the diagonal measurements are equal.

Where the two diagonal strings cross, drive a stake into the ground to mark the position of the center footing.

Once squared, make a mark along each string 42 inches from the corner in both directions. Use a plumb bob and chalk to transfer each mark from the string to the ground, and drive a stake to mark the center of each post position. The measurement from post center to post center should be 60 inches.

Prepare the footings