DCA 6 Deck Construction Guide – New Version for 2012 IRC
My favorite guide for designing and building decks – the American Wood Council’s DCA 6 – has been updated to dovetail with the 2012 International Residential Code (IRC). Whether you’re a construction professional or a DIY, DCA 6 will guide you through all aspects of deck construction with nuts-and-bolts details and tables. Most building officials recognize American Wood Council’s publications as providing ‘code-compliant’ information and practices; so when you use DCA 6 as your deck-building guide, you can be pretty sure there won’t be any snaggs when it comes time for inspections.
Users of the 2009 IRC version of DCA 6 will notice a few changes in the 2012 version including:
- The Joist Span table now includes 2x6s (though rim joists and ledgers must be minimum of 2×8).
- The tables for joist (Table 2) and beam (Table 3A) spans / spacing have been updated to current species design values.
- New table (Table 3B) for Glue Laminated Timber Beam spans.
- Diagonal post bracing is now illustrated (Figure 10) in the post requirement section rather than the free-standing deck section.
- Diagonal post bracing is not required/recommended on mid-beam posts. Only the end posts are braced. No diagonal bracing is required between the posts and the joists.
- The Footing Size table (Table 4) is expanded to include maximum post height based on beam and joist span.
- Minimum footing sizes in Table 4 based on beam and joist spans have increased. This was done to account for the dead load of the concrete footing itself.
- The footings at the end of a beam can be smaller than mid-span posts (see Table 4 footnote 2).
- There are additonal footing design options (Figure 12)
- The ledger to CMU detail has been eliminated.
- There are new lateral load connection details for I-joists and house joists perpendicular to the deck joists.
- Free-Standing decks are referred to as “Non-ledger” deck.
The new DCA 6 version doesn’t have a commentary yet; but it’s its way.
There’s a thorough DCA 6 walk-through video program produced by the American Wood Council available. The first 45 minutes covers DCA 6. Then the program turns to the NDS, some engineering talk , and how NDS is incorporated into the prescriptive measures of DCA 6 for another 45 minutes or so; and continues with Q&A for 30 minutes.
If you are curious why carriage bolts are not permitted for wood construction purposes – the presenters address it at 1:52 into the presentation.
You can view the program slides at http://www.awc.org/pdf/education/20140522_webinar_dca6_2012ircversion.pdf