Measure the area where you will build the porch. To make the job easier, plan to build a square or rectangular porch.
Determine how much lumber you need based on your measurements. The thickness of frame, in inches, should equal the number of feet in the porch's overall length. For example, if your porch is 10 feet long you should build your porch frame using 2-by-10s.
Remove the trim and siding from the part of the house where you will attach the porch, if necessary, using a power drill and crowbar.
Cover the exposed wall with self-adhering waterproof membrane. Cut away the excess with a knife.
Mark the spot with a chalk line where the top of the deck will meet the wall.
Divide the length of the wall by 2 after rounding up to the next whole foot. Cut this many 1 1/2 inch thick wood spacers, 2 inches long, and attach them every two feet below the chalk line using 6d nails.
Cut 2 2-by-6 pieces of wood to the length of the porch. Nail them together evenly and attach them to the chalk line wall, aligning them with the tops of the spacers and nailing them into the spacers with the nails. The long, thick piece of wood is your ledger board, and a source of support for the porch.
Drill 3 1/2 inch holes into the ledger board at every spacer using the power drill.
Insert 1/2 inch lag screws and washers into each hole.
Cut another piece of the waterproof membrane to the length of the ledger, 6 inches wide.
Fold the length of membrane lengthwise to form a right angle and attach it to the top of the ledger board with nails.
Place roof flashing over the membrane and any gap that remains between the finished house wall and the ledger board, and nail into place with roofing nails.
Mark the two corners opposite the ledger board by sticking wooden stakes into the ground at each spot. Place a stake between these two markers every 8 feet along the line that will be the front edge of the porch.
Dig a hole, approximately 2 feet wide and 2 feet deep, at each stake with a shovel.
Place cardboard forms, shaped as cylinders, into each hole. The top of the forms should be level with the bottom of the ledger board.
Fill each form with cement and allow it to stand for at least 24 hours.
Drill 1-inch holes into the center of each concrete footer once the cement has set.
Place anchor bolts inside each hole in the footers.
Build the frame of the deck using 2-by-10 pieces of wood (or another width based on your own measurements) that you nail together. The frame will serve as the outside edges of the porch. Attach the front edge of the frame to the anchor bolts on the footers. The end of each side rail should bolt into the ledger board. The ledger board will serve as the back edge of the porch frame.
Nail double-joist hangers to the inside of each side rail, spaced every 2 feet. Nail hangers along the front board and the ledger board, one directly in the center and additional hangers every 8 feet. Each hanger should be perfectly in line with the one directly opposite.
Place 2-by-10 pieces of wood into the joist hangers along the front and back boards and nail into place using the existing joist hanger holes. Nail joist hangers into these joists, on either side, to match the positioning of the hangers placed along the side rails.
Place 2-by-10s, cut to size, into the remaining joists. When you are finished you will have a crosswork of wooden beams, joists, that create the entire support frame for your porch.
Attach deck boards, spaced 1/2 inch apart, across the entire length and width of the porch, using deck screws.
Paint or stain the wood as desired.
Things You Will Need
- Tape measure
- Power drill
- Self-adhering waterproof membrane
- 6d nails
- Roofing nails
- 1 1/2 inch wood spacers, 2 inches long
- Roof flashing
- Wooden stakes
- Anchor bolts
- Double-joist hangers
- Deck boards
- Deck screws
- Consult with your local permit office to learn if you must file any paperwork or following any special building codes prior to creating the porch.