I have a Cantilevered bay window that is about 7' wide I need to frame around. The ledger board is on both sides. The Residential Deck construction guide says it can not be wider the 6'. It states that 1 or more 6x6 post can be added to reduce the span. Since this is with in 5' of my wall, and it is at the top of my basement my footer depth may be 8 feet.
The house has been build for 30 years but I guess the dirt could still be considered backfill. Do I need to dig all the way down to my foot for the one 6x6 post? If so how do I go about doing it?