Loading

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"
 2-2x1010'-1"8'-9"7'-9"7'-1"6'-6"6'-1"5'-9"
 2-2x1211'-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"
 3-2X810'-7"9'-3"8'-3"7'-6"6'-11"6'-5"6'-1"
 3-2X1012'-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"
 4X109'-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.


Popular Framing Articles
Deck Support Columns

How to Decorate Deck Support Columns

Browse some examples of decorative deck support posts for tall decks.

Deck Support Beams

How to Use a Triple Deck Beam to 6x6 Post Connection

Learn how to use a post beam connector to attach a 3-2x10 beam to a support post for a deck when there isn't enough material on the post to create a notched connection.

Deck Framing

Pool Decks

Decks constructed around above-ground pools are no different than any other free-standing deck.

Next Step: Decking Articles
Decking Installation

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.

Decking Installation

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 Installation

How to Install Composite Decking

Learn about how to install composite decking. Topics include expansion and contraction issues and hidden fastener systems.

Get more helpful resources delivered right to your inbox

Explore Articles by Topic

Popular Framing Articles
Deck Framing

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 Framing

How to Build a Freestanding Deck

You may need to build a freestanding deck if you can't attach a ledger board to the house. Learn how to build a self-supporting deck.

Deck Support Columns

How to Decorate Deck Support Columns

Browse some examples of decorative deck support posts for tall decks.

Next Step: Decking Articles
Decking Removal

How to Demolish & Remove a Deck

At some point, it might become necessary to remove an old deck, due to age or condition. Learn more about what's involved in a deck demolition and removal project.

Decking Installation

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.

Decking Installation

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.

Get more helpful resources delivered right to your inbox

Explore Articles by Topic