How To Build an Octagon Deck
The most important thing to be concerned with while building an octagon deck is to keep it level and square. We recommend to start by setting the prenotched posts at each corner positioned at a 22.5 degree angle. Between each of these posts, you will install double flush beams. Make sure each beam is the same length and equidistant to the opposite side.

The perimeter framing will be flexible for you to adjust before adding additional framing. Use temporary supports to stabilize the frame while working. Once the deck perimeter is square and level, install joists using angled joist hangers to strengthen the octagon frame. Avoid installing joists to the corner intersections to prevent interfering with the post beam notch connections. Adding decking and bracing will improve the strength and structural stability of the octagon.
If you are planning on installing a gazebo on top of the octagon, make sure your footings are sized to support the extra weight of the roof and that the gazebo is properly attached to the frame.
How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
How to Create Strong Post-to-Beam Connections
Learn how to create a positive structural connection for your post to beam connections. Use lag bolts, through bolts with washers, support cleats and hardware connectors.
Decking Patterns
Installing your decking at a 45-degree angle is a popular style for decks. This can be done to reduce decking seams or just for appearance.
Best Hidden Fasteners for Decking
Hidden fasteners create a clean deck surface and can be used with composite, wood and other materials. Learn about hidden deck fasteners at Decks.com.
Introduction to Decking
Spacing between deck boards provides several critical functions, such as drainage & drying. Learn how to space and stagger deck boards at Decks.com.
More Helpful Resources
Explore Articles by Topic

Footings
Information related to installing frost footings for decks

Framing
Learn structural framing methods

Decking
Learn about wood and composite decking materials

Stairs
An in-depth look at the complex issue of how to build stairs

Railings
How to install guardrails and handrails to meet IRC code

Features
An overview on water drainage, benches, planters and lights

Design
The basics of deck design

Planning
Learn about permits and working with contractors

Porches & Patios
Build a covered deck to enjoy all seasons

Ledger
Proper attachment techniques

Care
Maintain your deck to maintain your investment

Materials
An overview on water drainage, benches, planters and lights
How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
Beam Span Chart
Learn how to size your deck beam using this easy-to-use span table. Just cross-reference the post spacing and joist length to determine the beam size.
How to Install Wood Deck Support Posts
Installing wood deck posts on top of concrete footings will provide additional support for your deck. We recommend using 6x6 posts due to their strength. Learn how install them at Decks.com.
Decking Patterns
Installing your decking at a 45-degree angle is a popular style for decks. This can be done to reduce decking seams or just for appearance.
Best Time to Build a Deck
People often wonder when the best time to build a deck is. Learn why building a deck in winter or fall might be your best bet.
Decking Patterns
Installing your decking at a 45-degree angle is a popular style for decks. This can be done to reduce decking seams or just for appearance.
Explore Articles by Topic

Footings
Information related to installing frost footings for decks

Framing
Learn structural framing methods

Decking
Learn about wood and composite decking materials

Stairs
An in-depth look at the complex issue of how to build stairs

Railings
How to install guardrails and handrails to meet IRC code

Features
An overview on water drainage, benches, planters and lights

Design
The basics of deck design

Planning
Learn about permits and working with contractors

Porches & Patios
Build a covered deck to enjoy all seasons

Ledger
Proper attachment techniques

Care
Maintain your deck to maintain your investment

Materials
An overview on water drainage, benches, planters and lights