Do Preliminary Work
Measure your proposed deck area. Determine where you want to place stairs as well as support posts. If the ground where you plan to build a deck can't properly support the weight of the deck, you may need to be flexible about its size and location.
Apply for building permits for your deck kit. Since this process may take a while depending on your municipality, it's good to have the paperwork in hand when you purchase your deck kit.
Contact your local utilities to make sure there are no underground water, sewage, phone or electrical lines under where you plan to dig the support posts for the deck.
Purchase the Deck Kit
Assess how much of the work you are capable of doing. You can find a deck kit that is just right for your carpentry skill set. Study deck plans that are in your price and size range. Find out what, if any, extra hardware you need to purchase to complete your deck kit.
Lay out the pieces of the deck for easy assembly. Read and follow all instructions that come with your deck.
Build a Deck onto Your Home
Pour the concrete footings for your deck. You should do this a few days before you actually assemble the deck so that the concrete can cure. Follow the recommendations of your deck kit to get footings the right thickness and diameter. If anchor bolts or connectors need to be set in the concrete, be sure to follow directions exactly so that you get the deck properly anchored.
Attach the ledger board to the house. This step may be optional depending on your kit. The deck kit attaches to the ledger board, but some deck plans call for a freestanding deck.
Connect the floor joists with the supporting posts. Secure the wood with the appropriate fasteners. Set the supporting posts in place on their footings and fasten them in place.
Set the deck rails in place. You may or may not have to do some assembling depending on the deck kit you purchased. Attach the deck rails to the supporting posts.
Put the floor in place. With a deck kit, the underlying support system is a part of the flooring system. You may need to connect the flooring to the ledger board to attach the deck to your house.
Add the stair rails to the deck. Put the stair treads in place. Complete the deck by staining it if required.