to the span in inches divided by 360, and is based on live load only. the load duration factor, c d, is 1.0. listed spans are for wet-service conditions, pressure-treated southern pine floor/deck joists, mc 19%. check sources of supply for available grades and sizes. maximum spans were calculated using design values effective june 1, 2013.
building codes for residential decks only require 40 psf. the longer the joist, the more area of deck the joist supports, and thus the beam supports. for pressure-preservative-treated southern pine no. 2 grade, there is a method that can be used for estimating beam spans for a preliminary design.
decks get wet and may be framed with incised treated lumber so spans may have to be adjusted. until a few years ago, the irc didn’t have deck joist span tables. but the 2015 irc included a new one (table r507.5) that will make it easy for deck builders to spec a joist size for a given span and joist spacing.
deck joist sizing and spacing enjoying your deck on a beautiful summer day is the perfect way to entertain guests outside or just unwind and relax. and while it’s important to have a deck that’s aesthetically pleasing to you, the most vital part about your deck is making sure it’s structurally sound.
deck beam span table deck joist span table deck joist rule of thumb deck & porch construction & structural fasteners deck & porch post & beam connectors: steel post cap connectors, plywood post to beam cleats, other connectors deck & porch railings, code requirements, safety deck framing tables, codes, specifications questions & answers about allowable spans for deck, floor, or porch framing.