The 5th edition - Residential code, section R507: Decks, does not address beams for exterior free standing decks.
Does a single 2 x 4 Southern Pine No. 2 beam meet code requirements for beams supporting floor joists on an exterior deck?
Interpretation #7902
Published June 21, 2017
Original Request
- Code Version
- 2014
- Code
- RESIDENT
- Code Description
- Chapter
- 5
- Section
- Section R507: Decks
- Topic
- Supporting Beams
Question
Answer Published 06/21/2017 at 12:06 PM
We need to dig out the engineering books for this one. Check the new span tables (they were changed a year or so back when it was determined that the currently available lumber is not as dense as old first growth was), determine the live and dead loads, check the load capability of the straps and brackets to be used, the shear strength of the fasteners, and proceed to design it.
Commentary
R507 only addresses ledgers. There are no prescriptive beams in the code book. The deck, including the beams, needs to be designed for live loads per Table R301.5 and wind loads per R301.2.1. And, no that side nailed 2 x 4 is not sufficient.