Decking

A deck lives or dies at two points: the footings and the ledger.

Footings go below the frost line so your deck does not heave and drop every winter. The ledger gets bolted and flashed properly, because a badly flashed ledger rots the rim joist of the house behind it, and that is the failure that actually hurts people.

Above that it is your call. Pressure treated is the value option, and composite costs more but you never sand or stain it again. Whichever way you go, the estimate names the decking being priced, so you can hold it line by line against anyone else's. The crew that digs the footings is the crew that sets the last rail, no more than a third of the price is due up front, and estimates are free anywhere inside 100 miles of Seekonk.

Decks come down at the ledger

When a deck fails it is almost never the boards. It is the ledger, the board that fastens the whole thing to the house. It fails in one of two ways: it was nailed instead of bolted, or water got behind it and rotted the rim joist it was bolted to.

So that is where your money goes. Through bolts or structural screws to a schedule, not nails. Flashing over the top of the ledger and up behind the siding, so water sheds out in front of the deck instead of soaking into the band joist. And a gap behind the ledger where the detail calls for one, so the back of it can dry. Not every deck hangs off a house either: a freestanding deck stands on its own posts, there is no ledger to blame, and the whole load comes back to the footings.

How the job runs

Footings to frost depth Dug, inspected and poured below the frost line, because in this climate a shallow footing lifts every winter and the deck racks.
Ledger on and flashed Siding cut back, flashing over the top and behind the wrap, hardware bolted to the schedule.
Frame, then hardware Joist hangers fully nailed with the right fasteners, not roofing nails, and post to beam connectors rated for the load.
Deck boards down The boards go on first, then come the parts you actually put your hands on.
Stairs, then rail Stairs and rail go in after the boards, and the stairs get the most attention because that is where people fall.
Rail tested by leaning You watch while the finished rail gets leaned on, hard.