How to build a pergola
A pergola is one of the most forgiving framing projects — four plumbed posts, two beams, a row of rafters, and you have shade, structure, and a reason to spend the weekend outside. Budget roughly $500–$2,000 depending on size and lumber.
Overview
A pergola is an open-roof structure of posts, beams, and rafters. The framing is simple, but the details matter: footings below the frost line, posts plumb in both directions, and evenly spaced rafters. Most builds take one to two days.
Step 1: Plan the size and location
Decide the footprint and where it sits — over a patio, walkway, or garden seating area. Check clearances from the house and property lines, and confirm with your local building office whether you need a permit. If the pergola attaches to the house, plan a ledger and footings sized to the roof load. For most freestanding pergolas, a plan is enough.
Step 2: Set the footings
Dig holes at each post location — typically 8–10 in diameter and below the frost line, then set cardboard concrete tube forms and pour concrete. Use the concrete calculator to estimate bags. Set a galvanized post base into each footing before the concrete hardens, and keep the tops level with each other.
Step 3: Install the posts
Drop each post into its base, check it plumb in both directions with a level, and tighten the anchor. Brace the posts with temporary diagonal boards so they hold true while you install the beams. Use pressure-treated posts where the frame is exposed to weather.
Step 4: Attach the beams
Run the beams across the top of each row of posts — double beams are common, with the two members sandwiching or overlapping the post tops. Notch the posts for a clean seat, or bolt the beams to the sides. Make sure the beams are level and square before moving on.
Step 5: Install the rafters
Lay out the rafter spacing evenly across the beams — 16–24 in on center is typical. Set each rafter on edge (taller than it is wide) so it carries load well, and fasten with screws or rafter brackets. Estimate total board feet with the lumber calculator before you shop.
Step 6: Add bracing and finish
Add diagonal corner bracing between the beams and posts, or attach a lattice top, to resist racking. Then seal everything: apply exterior stain or sealer to all exposed lumber before it weathers. The paint calculator estimates how much finish you need.
Cost and time
- Materials: $500–$2,000+ depending on size and lumber grade; concrete, anchors, and finish add $150–$400.
- Time: 1–2 days for a small freestanding pergola.
- Tools: post-hole digger, circular saw, level, drill, tape measure, stepladder.
Tips for a sturdy pergola
- Set footings below the frost line so posts don't heave in winter.
- Plumb every post in two directions before bracing.
- Use galvanized anchors and exterior screws or lag bolts.
- Seal pressure-treated ends cut on site to keep moisture out.
- Check local clearances if the pergola is close to a property line.
Disclaimer
This guide is general information, not professional engineering. Footing depth, clearances, and permit rules vary by location. If the pergola attaches to your house or supports any roof load, have the connection reviewed by a qualified professional before building.