Framing the Deck of the Screen Porch
Choose the shape of the deck for the screen porch that you wish to build. A square or a rectangle would make excellent choices as they are the simplest shapes to build.
Affix a ledger board or a band board to your house. Be sure you mark exactly where the ledger board should go before securing it. The ledger board's function is to support the floor joists of the deck for the screen porch as they extend away from the house. Check with your town office to find out what your local building code will be for the attachment of the ledger board, for this can vary from state to state. Simple lag bolts or nails would not be sufficient fasteners in this application.
Line up your joists by determining where the floor joists inside the house are located. In this manner, you can extend the joists of the screened porch you are framing so they can be extensions of these joists.
Attach two end floor joists to the ledger board. Take a joist hanger and hammer it until it is flat, then use it to attach your end joists to the ledger board by nailing it to the ledger board's side or end.
Add an outer ledger board or rim joist to finish framing the deck of the screened porch. Support the deck frame by tacking 2-by-4 inch boards to the joists. Place scraps of wood beneath the 2-by-4 inch boards to prevent them from sinking into the ground. Make your deck for the screened porch you are framing as level as possible.
Make the deck of the screened porch you are framing square by checking that each of the corners are 90 degrees. Measure the deck from the diagonals with a tape measure. If the two diagonals are the same, then your corners are square.
Insert the post into the hole with the concrete you poured the day before. Fill around each of the posts with "rounded gravel" so that the gravel reaches to about 6 inches from the grade. Fill the rest of the way with concrete as you create the deck of the screened porch you are framing. This will make it easier to remove the post should it become damaged or need replacing.
The Foundation of the Screen Porch
Use a plumb bob to determine where to form the piers for the deck of the screened porch you are framing. By dropping a plumb bob beneath the corners of the deck, you will be able to find the center of the corner-the best place for the pier's placement.
Dig the holes for the piers with post hole diggers. These you can find at any hardware store or building supply store. Make sure you dig to, or a bit below, the frost level in your part of the country.
Pour 8 inches of concrete into the hole and let it sit for a day.
Notch or attach a joist hanger to posts that will be the foundation of the screened porch. These posts should be made of pressure treated lumber so that they will resist decay.
The Deck of the Screened Porch
Choose the lumber you wish to use as the deck or floor of the screened porch you are framing. If you choose wood, make sure it's pressure treated, or chose composite wood material instead.
Prefinish the boards if you use pressure treated lumber with a sealer so that the lumber that is exposed beneath the deck will not be exposed to the possibility of rotting.
Lay the deck down without leaving any spaces between the boards and nail them in place.
Install "electrical feed wires" from the house if you plan to have any light fixtures or fans in the screened porch you are framing. You can also install a gas line for your grill.
The Walls of the Screened Porch
Decide the size of the screened panels you wish to use when you frame your screened porch.
Help make your decision by researching the width of the screening material that is available. A local lumber company or a building supply store could help.
Buy pre-fab panels or have them custom made for you so that they will fit the dimensions of the screened in porch you are making. Remember to leave room for the posts that hold the screen panels in place as well as support the roof.
Wait until the last day of construction to install them.
Support Posts for the Screened Porch
Choose the lumber you will use for the support posts of the screened porch you are making. You can use pressure treated lumber, or even redwood or cedar.
Install "intermediate support posts" on which the beams will rest.
Use galvanized post and beam hardware to connect the beams to the posts. This hardware is available at building supply stores or online.
The Roof of the Screened Porch
Match the pitch as well as the shape of your house's roof when you build the roof of the screened porch you are framing.
Create an overhand for the screened porch's roof that is at least 16 inches long.
Take your time fitting and cutting the rafters as you build the roof of the screened porch you are framing. Consider pretreating them before installing the rafters. Any work you can do to help prolong the life of your screened porch is worth the extra effort.
Lay plywood down as a sheath for the roof of the screened porch you are framing. You might consider treating the plywood before installing it so as to protect it from water penetration.
Install a waterproof membrane on top of the plywood sheathing, then roofing shingles that match those of your house.
Finishing the Screened Porch
Prime and also paint any lumber before you install it, especially on the edges.
Paint the screen panels before you install them.
Install the screen panels into the screened porch you are framing.