Beam Span Chart Table
The span of a beam is dependent on a few variables: The grade and species of lumber, size of lumber and the load it carries. Fewer posts on upper-level decks are typically more desirable to the occupants and this drives the use of larger framing materials for longer spans. Beam span maximums are based on a maximum anticipated live load as well as other factors. Building codes for residential decks only require 40 psf in some areas, but check your local requirements to make sure you are aware of any additional local guidelines. In addition, many residents prefer the fell of a deck that is designed for higher loads. The longer the joist, the more area of deck the joist supports, and thus the beam supports more area as well.
Dimensional Lumber Deck Beam Span Chart
Note: The span chart below is an example of how spans charts are presented. Because building code and lumber spans are updated from time to time, you should always check to make sure the span chart you are using is up to date. See the applicable code section, or the NDS to confirm the span chart you are using is correct.
Dimensional Lumber Deck Beam Spans Supporting a Single Span of Joists with or without Overhangs:
| Joist Spans | ||||||||
|---|---|---|---|---|---|---|---|---|
| Species | Size Beam | 6' | 8' | 10' | 12' | 14' | 16' | 18' |
| Southern Pine | 2-2x6 | 6'-8" | 5'-8" | 5'-1" | 4'-7" | 4'-3" | 4'-0" | 3'-9" |
| 2-2x8 | 8'-6" | 7'-4" | 6'-6" | 5'-11" | 5'-6" | 5'-1" | 4'-9" | |
| 2-2x10 | 10'-1" | 8'-9" | 7'-9" | 7'-1" | 6'-6" | 6'-1" | 5'-9" | |
| 2-2x12 | 11'-11" | 10'-4" | 9'-2" | 8'-4" | 7'-9" | 7'-3" | 6'-9" | |
| 3-2x6 | 7'-11" | 7'-2" | 6'-5" | 5'-10" | 5'-5" | 5'-0" | 4'-9" | |
| 3-2X8 | 10'-7" | 9'-3" | 8'-3" | 7'-6" | 6'-11" | 6'-5" | 6'-1" | |
| 3-2X10 | 12'-9" | 11'-0" | 9'-9" | 8'-9" | 8'-3" | 7'-8" | 7'-3" | |
| 3-2X12 | 15'-0" | 13'-0" | 11'-7" | 10'-6" | 9'-9" | 9'-1" | 8'-7" | |
Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine | 3X6 OR 2-2X6 | 5'-2" | 4'-5" | 3'-11" | 3'-7" | 3'-3" | 2'-10" | 2'-6" |
| 3X8 OR 2-2X8 | 6'-7" | 5'-8" | 5'-1" | 4'-7" | 4'-3" | 3'-10" | 3'-5" | |
| 3X10 OR 2-2X10 | 8'-1" | 7'-0" | 6'-3" | 5'-8" | 5'-3" | 4'-10" | 4'-5" | |
| 3X12 OR 2-2X12 | 9'-5" | 8'-2" | 7'-3" | 6'-7" | 6'-1" | 5'-8" | 5'-4" | |
| 4X6 | 6'-2" | 5'-3" | 4'-8" | 4-3" | 3'-11" | 3'-8" | 3'-5" | |
| 4X8 | 8'-2" | 7'-0" | 6'-3" | 5'-8" | 5'-3" | 4'-11" | 4'-7" | |
| 4X10 | 9'-8" | 8'-4" | 7'-5" | 6'-9" | 6'-3" | 5'-10" | 5'-5" | |
| 4X12 | 11'-2" | 9'-8" | 8'-7" | 7'-10" | 7'-3" | 6'-9" | 6'-4" | |
| 3-2X6 | 7'-1" | 6'-5" | 5'-9" | 5'-3" | 4'-10" | 4'-6" | 4'-3" | |
| 3-2X8 | 9'-5" | 8'-3" | 7'-4" | 6'-8" | 6'-2" | 5'-9" | 5'-5" | |
| 3-2X10 | 11'-9" | 10'-2" | 9'-1" | 8'-3" | 7'-7" | 7'-1" | 6'-8" | |
| 3-2X12 | 13'-8" | 11'-10" | 10'-6" | 9'-7" | 8'-10" | 8'-3" | 7'-10" | |
Assumes 40 psf live load, 10 psf dead load, L/360 simple span beam deflection limit, cantilever length L/180 deflection limit, No. 2 Stress grade, and wet service conditions.
How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
How to Angle Corners and Joists
Learn how to frame a deck with angled or clipped 45-degree corners using a cantilever beam.
Framing a Deck Parallel to a House
Learn about an alternative framing method that allows you to install your decking perpendicular to the house and makes the deck free standing.
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.
10 Common Deck Building Mistakes & How to Avoid Them
Building a deck can be a complicated process. Learn how to avoid falling into common deck building pitfalls with tips and advice from the experts at Decks.com.
Building an Outdoor Space with James DeSantis
Composite decking can not be placed directly on concrete. But a substructure can solve for this. Explore this deck project with James DeSantis
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
Why is Joist Protection so Important for Your Deck?
If you’ve ever seen a piece of wood left out in the weather for any period of time, you know what happens: decay. Whether through wet rot, insect damage, or mildew, the fibers begin to break down.
How to Build a Multi-Level Deck
Multi-level decks are very popular. Learn how to build a deck that steps up or down using shared posts and footing connections.
How to Build a Ground Level Deck
Adding a ground level or floating deck to your home may be the perfect addition to your outdoor space. Learn how to build a ground level deck at Decks.com.
Building an Outdoor Space with James DeSantis
Composite decking can not be placed directly on concrete. But a substructure can solve for this. Explore this deck project with James DeSantis
6 Best Alternatives to Wooden Decking
While wood decking was previously considered the standard material for building a deck, that’s changed. Homeowners have been exploring and embracing different types of materials, and the availability of alternative decking materials has grown significantly.
Picture Frame Decking
Install a picture frame or perimeter board to finish the edge of your deck with style.
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