As others have stated. When building a deck
1.) The ledger needs weatherproofing behind it, can't be aluminum (aluminum was allowed in the past when pressure treated didn't eat metals like crazy). Todays pressure treated eats metal like candy, it's why you can't use just galvanlized screws/nails for the structural components they will be toothpicks in short order. If you want your deck to last more than 10-15 years you should use stainless hardware. Todays PT is so corrosive to metals they've found even galvanized is having trouble holding up and beginning to sell double-dipped galvanized. Could I do my deck again, I'd pay the extra for stainless hardware. Moisture increases the speed at which PT eats metal so stainless would be particularly advantageous in wetter places.
2.) To attach the ledger to the rim joist the rim joist must be sound and lags or bolts used. There's specific requirements to spacing of lags and bolts along with their size and they must be visible from the inside for the inspector to make sure they penetrated. If you can't prove they penetrate to the inside (say the inside room is finished) then you must use special lags/screws called LedgerLok (sold pretty much everywhere) whose heads are stamped. When the inspector comes and see's the stamp on the heads he knows you used an engineered product specifically designed for attaching decks safely to the rim joist and no need for them to verify you penetrated the inside.
3.) The posts for railings must be 4x4 PT, not notched (there's a very high horizontal load requirement that 4x4's just meet. Notch them and they will be too weak to meet the requirement). They must be bolted with 1/2" galvanized bolts using special fasteners on the top bolt that look like
http://nolan-engineering.com/wp-content/uploads/2014/10/deck-to-railing-connection3.jpg as the top bolt is the pivot point and needs bracing to prevent it from failing with the horizontal force requirement. The railings must be at least 36" high off the deck floor, with no more than 4" spacing allowed between balusters, and the way some people do it of just using balusters attached to the outside doesn't meet the requirements. To have a chance of surviving the horizontal load requirement they'd have to go on the inside of the supports, but then there's the situation mentioned already today's PT eats screws and nails like a kid eats candy, balusters only attached to the outside will have the screws looking like toothpicks in short order, think it's going to stop an adult falling/slamming into it having only balusters no posts and beams, only attached to the outside, and attached using screws which the PT has turned into toothpicks?
4.) Overhangs can't be more than 2' beyond the supports.
5.) Do a floating deck if possible particularly in wet places. It happens way too often someone finds out their rim joist is rotted because of how a deck was installed, and even if you do it right it's not going to be as good as if you just did a floating deck. My house I attached it to the ledger since my deck is on the 2nd floor but could I go back I'd have sucked it up and done floating.
