It's been there without sagging, with added weight of an insane vine growth and occasional snow, for nearly 20 years. Our own little pergola, a bit smaller than yours, that I built using 2x10s around the perimeter of a 20 x 15' pergola is supported on 6圆 posts, 2x10s through bolted to the posts the joists are simple 2x4s 16' o.c. I’m doing a 14ft x 14ft deck double 2x12 beams outside and center 2x8 joist how many 6圆 posts should I use?Īnon you need to either meet standard flat roof framing specifications (which is over-building since there's no weight of the roof that's not going to be installed atop the joists) OR have an engineer do the calculations for you since the frame is almost a zero load except for the weight of the framing itself - not something in the framing tables. That is why I am asking this question here. I can't find anything anywhere that will support this information. Builder used 4'圆' df girders spaced 5' apart in width with posts beneath girders spaced 6' apart then toenailed 2'x 8' T&G DF perpendicular to girders. The Southern Forest Products Association's (SFPA) current suggested lumber spans are found at 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.ĭetails about the evolution of lumber standards are Rapid tree growth means wide-spaced growth rings which may mean softer, weaker wood than dense-grained first-cut timbers or lumber. Modern 2x lumber is produced from trees that have been developed to grow rapidly to a size at which they can be harvested. Our opinion is that modern dimensional lumber is not the same product as it was in 1833 or even 1940. Changing Wood Framing Span Tables & Modern Framing Lumber Strength

2 or better.ĭetails about selecting the proper fasteners for constructing decks and porches and how they are installed can be read at Deck Nails, Screws, Hidden Fasteners.Īlso see DECK COLLAPSE Case Study (collapse of a new code-approved deck)Īnd 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. Deflection allowed = span in inches / 360Ģ. Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons). Table 4-8 Maximum Spans for Deck Joists in ft-in 1 Table of Maximum Joist Spans for Exterior Decksįrom the joist span table image above we repeat:

The Southern Forest Products Association's (SFPA) current suggested lumber spans are found at Table of Maximum Beam Spans for Exterior Decks In Table 4-7 and Table 4-8 (shown below in this article) as well as in most carpentry texts and framing guides. Spans, sizes and spacings for deck joists and deck beams are shown Deck framing tables, codes, specifications.įraming span tables for all types of wood construction, not just decks, are given separatelyĪt 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.Īs explained in Best Practices Guide to Residential Construction, Chapter Four, Best Construction Guide for Building Decks and Porches Deck Joist & Beam Sizing Tables & A Quick Rule of Thumb for Sizing Joistsįind here: Framing span tables for decks, porches, other common building floor structures. We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Our page top photo shows a small deck addition to a 1920's bungalow in Poughkeepsie NY. 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. We have no relationship with advertisers, products, or services discussed at this website.įraming tables for decks: joist & beam spans & sizes. InspectAPedia tolerates no conflicts of interest.

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