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Framing nails to excess (C) Daniel Friedman Deck Construction Framing Tables

Joist, Beam, & Floor Framing Spans & Tables

Framing tables for decks: joist & beam spans & sizes.

Recommended or allowable joist & beam spans: this article explains typical spans for deck joists, deck beams, and deck flooring, giving both standard span tables and a quick "rule of thumb" that works pretty well.

Our page top photo shows a small deck addition built by D. Friedman as an addition to a 1920's bungalow at 227 Vassar Road in Poughkeepsie NY. The building department, in respect to current property line setback requirements, accepted the deck plan so long as it did not extend the full width of the home.

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- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Deck Joist & Beam Sizing Tables & A Quick Rule of Thumb for Sizing Joists

Table 4-7: Maximum Beam Spans in Feet for Exterior Decks (C) J Wiley, S BlissFind here: Framing span tables for decks, porches, other common building floor structures. Deck beam span table. Deck joist span table. Deck joist rule of thumb. Deck framing tables, codes, specifications.

Framing span tables for all types of wood construction, not just decks, are given separately

at FRAMING TABLES, SPANS where in addition to span tables for dimension lumber & timbers, we also give a rough rule of thumb that gives the span for a common 2x joist.

As explained in Best Practices Guide to Residential Construction , Chapter Four, Best Construction Guide for Building Decks and Porches

Spans, sizes and spacings for deck joists and deck beams are shown in Table 4-7 and Table 4-8 (shown below in this article) as well as in most carpentry texts and framing guides.

The Southern Forest Products Association's (SFPA) current suggested lumber spans are found at http://www.southernpine.com/span-tables/

Table of Maximum Beam Spans for Exterior Decks

[Click any image or table to see an enlarged, more detailed version.]

Table of Maximum Joist Spans for Exterior Decks

[Click any image or table to see an enlarged, more detailed version.]

Table 4-8: Maximum Beam Spans in Feet for Deck Joists (C) J Wiley, S Bliss

From the joist span table image above we repeat:

Table 4-8 Maximum Spans for Deck Joists in ft-in 1
Joist Sizes: 2x6 Joists 2x8 Joists 2x10 Joists 2x12 Joists
Joist Spacing 12 in. 16 in. 24 in. 12 in. 16 in. 24 in. 12 in. 16 in. 24 in. 12 in. 16 in. 24 in.
Wood Species o.c. o.c. o.c. o.c. o.c. o.c. o.c. o.c. o.c. o.c. o.c. o.c.
Douglas fir - Larch 10-9 9-9 8-3 14-2 12-9 10-5 18-0 15-7 12-9 20-11 18-1 14-9
Hem-fir 10-0 9-1 7-11 13-2 12-0 10-2 16-10 15-2 12-5 20-4 17-7 14-4
Southern Pine "SYP" 10-9 9-9 8-6 14-2 12-10 11-0 18-0 16-1 13-2 21-9 18-10 15-4
Western Red Cedar 2 9-6 8-3 6-9 10-5 10-5 8-6 14-9 12-9 10-5 17-1 14-9 12-1

Notes to the table above

- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .

1. 40 lb. live load, 10 lb. dead load. Deflection allowed = span in inches / 360

2. Western red cedar No. 1/No. 2, all other lumber graded as No. 2 or better.

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Details about selecting the proper fasteners for constructing decks and porches and how they are installed can be read at Deck Nails, Screws, Hidden Fasteners.

Also see DECK COLLAPSE Case Study (collapse of a new code-approved deck)

and DECK FLASHING LEAKS, ROT Case Study for an example of an older deck with rot and collapse due to improper construction and missing building flashing.

Changing Wood Framing Span Tables & Modern Framing Lumber Strength

As we comment at DIMENSIONAL LUMBER,

Our opinion is that modern dimensional lumber is not the same product as it was in 1833 or even 1940. Modern 2x lumber is produced from trees that have been developed to grow rapidly to a size at which they can be harvested.

Rapid tree growth means wide-spaced growth rings which may mean softer, weaker wood than dense-grained first-cut timbers or lumber.

That combined with the increasing number of knots (as 2x's are cut from ever smaller trees) means that the building frame must rely on additional materials (such as plywood or OSB sheathing) for a critical part of its strength.

Details about the evolution of lumber standards are

at FRAMING AGE, SIZE, SPACING, TYPES.

The Southern Forest Products Association's (SFPA) current suggested lumber spans are found at http://www.southernpine.com/span-tables/

 

Thank you to our readers for their generous comments

Just wanted to say thank you for posting the 2x6 etc. deck span chart. I am building a deck at just 6 inches (beams are 4"x6"x12' with 3 supports on each beam) above ground level and have an 8 foot span and 2 foot overhang past the main beams.

It is good to know that I could go as wide as 9 feet at the span without compromising the strength overall. That would be quite a drop if I got it wrong, kidding ;o) On 2018-06-23 by Redhead

Reply by (mod) - rule of thumb for using 2x6's

Thanks for the thank you Red. We work hard to provide authoritative data so we're grateful when a reader finds it useful.

In Steve Bliss’ tables above Table 4-7 gives beam sizes (click to enlarge) and Table 4-8 gives joist spans.

A typical 2x6 SYP (the most common you’ll find at a Home Depot store or Lowes)

according to the table in FRAMING TABLES, SPANS when spaced 16” o.c. can span 9’9”

Our “rule of thumb” discussed earlier on this page and applied to a 2x6 would have given

(6-2)x2 = 8 ft. allowable span,

which would have been within the actual joist span table and would have been “safe”.

Questions, content criticism, content contributions, photos (of your deck) are entirely welcome.

- Editor

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Continue reading at DECK LAYOUT if you need to know how to lay out and square up the deck plan to set exact pier & post locations, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see DECK FRAMING TABLES, SPANS FAQs - questions & answers about framing tables, spans, sizes, strengths posted originally at the end of this page.

Or see these

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DECK FRAMING TABLES, SPANS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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Citations & References

In addition to any citations in the article above, a full list is available on request.

  • [1] Paul DeBaggis is a building inspector and certified building code official with special interest in the history of and standards for wood products. (The American Wood Standards Committee). Mr. DeBaggis has served in the Easton MA. Building Department since 2002 , has worked as a building trades instructor, and also writes about land use regulations, building regulations, and standards. He is a past president of Southeastern Mass. Building Officials and is currently writing a book on the Massachusetts building code. Email: paul@jenick.net
  • Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: info@buildingadvisor.com
    Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com
  • Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
  • Manual for the Inspection of Residential Wood Decks and Balconies, by Cheryl Anderson, Frank Woeste (Forest Products Society), & Joseph Loferski, October 2003, ISBN-13: 978-1892529343,
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

    CONTINUE READING or RECOMMENDED ARTICLES.

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