Installing deck joists for front porches is a serious and important task, they provide support and framing for your entire porch. Make sure you have all the appropriate tools for this endeavor. Follow the steps below to construct a secure foundation for your platform.
Step 1 – Check Regulations
Your local building codes will specify the exact type and size of the lumber that you need to use for deck joists. They may also designate the type of fasteners you need to use, and how many. Modify the instructions below so that they correspond to your local codes.
Step 2 – Install the Ledger Board
Fasten the ledger board to the exterior surface of your home, at the height you planned. For this porch, this should be a 2x10, 6 feet long. Use a level to make sure it's being installed in a straight fashion. This board should be secured with lag bolts with washers, every 2 feet across.
Step 3 – Make Concrete Pads
Dig 2 rows of 3 holes each, spaced equally apart, for concrete pads that will support the girders. As the concrete is drying, put the premade concrete pier on top, so that it’s level. These will hold the beams.
Step 4 – Set the Support Beams
Measure and cut 6 4x4 posts with the circular saw, that will be screwed onto each concrete pier to hold up the support beams. Measure the height of the ledger board and use the saw to cut the posts to this level. Screw on brackets to each of these posts. Cut the beams from 2x4's, 6 feet in length. Lay them across the brackets, perpendicular to the ledger. There should be 3 beams and each will lie across 2 brackets. Screw the beams into their brackets.
Step 5 – Install the Deck Joists
Joists are horizontal planks of wood that support the flooring of your deck. There are 2 different kinds of deck joists that you’ll be dealing with: rim joists and floor joists. You’ll be making a 6 by 6 foot square, by attaching 3 rim joists to the ledger board. Within the square, you’ll be installing 2 planks of wood perpendicular to your home – these are called floor joists.
Use the circular saw to cut 3 rim joists, which should be 4x8's, 6 feet long. Screw 1 into each side of the ledger board, at right angles. Now, screw in the third rim joist to the ends of the other 2, and finish the square.
Now, fill in the square with parallel deck joists. Screw in joist hangers every 2 feet on the side deck joists. Cut 2 floor joists to be inserted into these hangers, the same length as the other deck joists. Screw them into the joist hangers. At every point where the joist crosses the support beam, screw it in.