In this guide, we’ll walk through:

1. how to plan and size your pergola
2. the materials and hardware that matter most
3. step-by-step construction, from posts to rafters
4. finishing tips to protect your investment outdoors

Before You Build: Planning and Preparation

Before breaking ground, take time to plan your pergola properly. Good planning prevents costly mistakes and ensures your structure is safe, square, and compliant with local requirements.

Check Local Codes and Permits

Depending on your municipality, pergolas may require a permit—especially if they’re attached to your home or exceed a certain height.

Helpful resources:

1. International Code Council (general building guidance): https://www.iccsafe.org/
2. Your local city or municipal building department website

Choose the Right Size

Common pergola sizes include:

1. 10×10 or 10×12 – small seating areas
2. 12×12 – outdoor dining
3. 12×16 – entertaining or outdoor kitchens

Choose a size that allows room to move comfortably around furniture.

Choosing the Right Materials

Wood Selection

Outdoor structures are constantly exposed to moisture, UV rays, and temperature changes. Choosing the right wood makes a major difference.

1. Western Red Cedar – naturally durable, stable, lightweight, and resistant to decay and insects
2. Pressure-treated lumber – budget-friendly and durable, but heavier and requires corrosion-resistant fasteners

Learn more about cedar performance:

• Real Cedar (Western Red Cedar): https://www.realcedar.com/

Hardware and Fasteners

All outdoor fasteners should be hot-dip galvanized or stainless steel to prevent corrosion.

Trusted hardware resource:

• Simpson Strong-Tie outdoor connectors and post bases: https://www.strongtie.com/

Instructions

Step 1: Lay Out and Square the Pergola

Mark each post location using stakes or spray paint. Use string lines to connect corners and measure diagonally from corner to corner. When both diagonals match, your layout is square.

Why this matters: a pergola that starts out of square will stay out of square all the way to the roof.

Step 2: Install Footings and Post Bases

Pergola posts should never sit directly on soil.

1. Dig footings to the depth required for your climate (below frost line where applicable).
2. Pour concrete or install approved concrete deck blocks.
3. Use post bases to keep wood elevated and dry.

Post base reference:

Simpson Strong-Tie post base solutions: https://www.strongtie.com/

Step 3: Set and Brace the Posts

Place posts into their bases and use a level to ensure they are plumb on all sides. Temporarily brace posts with angled boards to hold them steady while you work.

Tip: Do not cut posts to final height yet—wait until beams are installed so everything aligns perfectly.

Step 4: Install Beams

Beams run horizontally between posts and support the rafters.

1. Beams are often doubled for strength.
2. Secure beams using rated hardware or structural bolts.
3. Check for level across the entire span before tightening fasteners.

Decorative beam ends can be cut at this stage if desired.

Step 5: Add Rafters

Rafters run perpendicular to beams and form the top structure.

1. Typical spacing ranges from 12 to 24 inches on center.
2. Keep rafter overhangs consistent for a clean finish.
3. Use exterior-rated fasteners or rafter hangers.

Closer rafter spacing provides more shade and a heavier visual presence.

Step 6: Install Purlins or Shade Slats

Purlins are optional but add shade and visual interest.

1. Run perpendicular to rafters.
2. Space evenly for consistent shadow patterns.
3. Pre-drill when working with cedar to reduce splitting.

Optional upgrades include retractable canopies, privacy panels, or lighting.

Step 7: Add Bracing for Strength

To prevent sway and movement:

1. Install diagonal knee braces at corners.
2. Secure all connections with exterior-rated hardware.

This step is especially important in windy or coastal regions.

Step 8: Apply a Finish or Protective Treatment

Even naturally durable woods benefit from a protective finish.

Finish Options

1. Semi-transparent stain 

2. Transparent stain 
3. Solid stain or paint

Allow wood to dry before finishing and reapply as needed over time.

Finishing and cedar care resources:

• Western Red Cedar Lumber Association (WRCLA): https://wrcla.org/