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Project Guide

How to Build a Pergola

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Red and blue utility flags in a lawn.

Before building a pergola, contact your homeowner association or local building codes office to determine if a permit is required or other restrictions apply in your area. Also, contact local utility companies before you begin. You will need to dig a hole below the frost line; knowing where the utility lines are first will prevent damage to pipes or power lines under the ground.

Prep the Area
A person digging a hole with a post hole digger.
  • Select the site for the pergola.
  • Measure an area that is 8- x 8-feet square.
  • Use spray paint to mark the area.
  • If you want a pergola that’s smaller or larger, adjust the sizing as needed.
  • Use a post-hole digger to dig a hole 24 inches deep by 9 inches wide at each corner of your outlined area.
  • Add 3 to 4 inches of gravel to each hole.
Level the Posts
A person pouring gravel into a hole in the ground.
  • Place the 4x4 posts in the holes. The tops will need to be level with one another, and each post will have to be plumb. Add or remove gravel as needed in order to level the tops of the posts.
  • Nail two 1x4 boards on the sides of one post as temporary braces. The braces should angle to the ground at 30-degree angles. Use a level against the side of the post to check that it’s plumb. This will temporarily hold the post in position.
  • Repeat with the other three posts.
Set the Posts
A person mixing concrete in a wheelbarrow.
  • Mix fast-drying cement according to the manufacturer's directions.
  • Pour into holes.
  • Use a thin, scrap piece of wood to “churn" the concrete in the hole. This will ensure that there are no air pockets in the concrete.
  • Let the concrete cure for 24 hours.
  • After the concrete cures, remove the braces.

Tip: If you are placing your pergola over a patio or any other stone surface, you’ll have use metal post anchors instead of digging holes.

Prepare the Crossbeams and Rafters
A stack of untreated lumber on the ground.
  • While the concrete is curing, you can prepare the 2x6 crossbeams and rafters.
  • The crossbeams carry the load of the pergola. You will need two beams on each side.
  • Optional: Cut a decorative angle on the ends of the rafters. To make simple decorative ends, cut 45-degree angle on the bottom corner at each end of the rafters.

Tip: Buy the beams and rafters precut to the size you need. This will save you time when it comes to installation. Your local The Home Depot will cut lumber to the size you need.

Install the Crossbeams
A man checking the level of a a crossbeam.
  • Install the crossbeam pairs on the posts first. 

Each beam consists of a pair of 2x6’s on either side of a post - an inner and outer beam.

  • Measure 5 1/2 inches down from the top of each post on the side that is facing the interior of the pergola. Mark it. Make another mark on the opposite side of the post. Repeat for all four posts.
  • Drive a 4-inch nail halfway through on each mark you made on the posts. This will temporarily hold the crossbeams.
  • Position inner and outer crossbeams onto the nails between the front set of posts. Make sure there’s a foot of overhang on either side. Use your level to make sure everything’s square and level. Temporarily screw them in place with 4-inch screws on each end.
  • Drill two 1/2-inch holes, one above the other, through both crossbeams and posts at each end.
  • Attach the beams to the posts using the carriage bolts, washers and nuts.
  • Repeat for the crossbeams on the rear set of posts.
  • The pergola should now have two cross beams running parallel to each other on each side of the structure.
  • Remove the nails and screws that temporarily held up the crossbeams.
Install the Rafters
A person installing a rafter.
  • Lay the rafters perpendicular across the crossbeams.
  • The rafters on the edges sit on the posts. Space the rafters a foot apart on center.
  • Make sure the overhangs are even on each end of the rafters.
  • Fasten the rafters in place by driving two 5-inch galvanized screws into the crossbeams at 45-degree angles.
A person staining a wood post.
  • Paint or stain the pergola to your satisfaction and allow ample time to dry before using.
  • Train vines or other climbing plants to grow over the rafters to provide a shady retreat.

If you are looking for an easier way to entertain under a pergola, try a prefabricated pergola. The Home Depot has pergola kits and all the supplies you need to build your own custom pergola.