The 2009 International Residential Code (IRC) has a number of big changes when it comes to framing decks. If your state, county or town will be adopting the ’09 IRC you’d better take a look at a copy of the code before you get a code violation.
The changes are all related to how you connect the ledger to the building. For one, there’s now a prescriptive chart for fastener patterns, no more ‘rule of thumb’ bolt or lag screw frequency. You just match the depth of your deck to your fastener of choice (1/2 inch lag screw, 1/2 inch thru-bolt or 1/2 inch thru-bolt with stacked washer space) and you’re good to go. But you are going to need a structural engineer if you want to bolt your deck ledger to anything but a 2x rim joist or a 1 inch thick Douglas Fir LVL rim. This means you have to know how the floor is framed when adding a deck to an existing building. Plus if the rim joist is concealed on the inside, you have to provide some sort of visual access for inspections – get out the hole saw….