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.
Decks vs. Patios: Cost, Pros, Cons, & Comparisons
Learn what factors affect the costs of decking and patios. Discover all the comparisons factors to help you choose the right space for your home with Decks.com.
Building A Deck Over An Air Conditioner
Things to consider when building a deck near an air conditioning unit. You may want to relocate the AC unit if possible to avoid some problems.
How to Install Decking Over Existing Concrete Slab, Patio, or Porch
Discover the best techniques to build a deck over concrete, ensuring proper drainage and stability, while creating a beautiful outdoor space.
Best Hidden Deck Fasteners
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.
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.
Deck Joist Water Protection
Learn about a technique used by many pro builders for wrapping deck framing lumber with a waterproof barrier to prevent corrosion and rot.
Roof Top Deck Construction
Rooftop decks transform otherwise wasted space into beautiful planes for entertaining, dining, relaxing and even gardening. The views will make your deck the talk of the neighborhood and draw frequent guests to your home or business.
What to Consider When Building A Wrap-Around Deck
Looking to add a wrap-around deck to your home but unsure of what the process involves? Check out this guide to learn more about top considerations when building a wrap-around deck.
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.
How to Install Decking Over Existing Concrete Slab, Patio, or Porch
Discover the best techniques to build a deck over concrete, ensuring proper drainage and stability, while creating a beautiful outdoor space.
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