Install a Pergola in Your Backyard

A pergola changes how you use your backyard. It stakes out territory, creates vertical interest, and casts that perfect dappled shade that makes a patio livable on summer afternoons. The structure itself is straightforward—four posts, perimeter beams, and cross rafters—but the work demands accuracy. Posts must be plumb, beams must be level, and everything needs to square up or the whole thing reads crooked from fifty feet away. The weekend breaks into two phases. Saturday is post day: dig footings, set posts in concrete, brace everything plumb, and walk away while it cures. Sunday is assembly: beams go up, rafters get spaced and secured, and by dinner you have architecture where there was only open ground. Most mistakes happen in the foundation—rushed footings or posts that drift while concrete sets. Get the posts right and the rest builds easy.

1. Square Up Before You Dig. Mark your four corners with stakes and string, measuring diagonals to confirm square—they should match within a half inch. Dig post holes 12 inches wide and 36 inches deep, or below frost line if your region requires it. Tamp 4 inches of gravel into each hole for drainage.
2. Lock Posts Plumb First. Cut your posts to length—typically 10 feet for an 8-foot finished height after burial. Set each post in its hole with a temporary cross-brace screwed near the top. Mix and pour concrete around each post, filling to 2 inches below grade. Use a level on two adjacent faces while the concrete is wet, adjusting braces until the post reads plumb in both directions.
3. Trim All Posts Level. Wait 24 hours minimum before removing braces or loading the posts. Use a laser level or water level to mark all four posts at the same height, then cut them with a circular saw. A pergola looks best with posts between 8 and 9 feet tall above grade.
4. Level and Bolt Perimeter. Cut two long beams to span the length of your pergola. Lift each beam onto opposing post pairs, resting them flat on top. Secure with two 6-inch structural screws or through-bolts per post, driven at opposing angles. Check that beams are level before final tightening.
5. Box In the Rectangle. Cut two shorter beams for the width and secure them across the open ends, connecting the long beams into a rectangle. These can sit flush on top or notch into the long beams if you want a traditional look. Secure with structural screws at each junction.
6. Space and Secure Rafters. Cut rafters to span the width of your pergola, adding 12 inches of overhang on each end. Space them 16 to 24 inches apart, marking locations on the long beams before you start. Toenail or use joist hangers to secure each rafter, keeping them perpendicular to the beams.
7. Finish Rafter Edges. If your design includes angled or shaped rafter ends, mark and cut them now with a jigsaw or miter saw. Common shapes include 45-degree bevels, gentle curves, or traditional Japanese-style cuts. Sand the cut edges smooth.
8. Seal and Inspect Everything. Brush or spray exterior-grade wood stain or sealer on all surfaces, hitting cut ends and connection points thoroughly. Walk the structure and check that all screws are snug, no beams have gaps at connections, and everything still reads plumb and level. Tighten any loose hardware.