How to Connect an Arbor to a Front Porch

Draw vertical pencil lines defining the outsides of the arbor on the side of the front porch, under the eaves of the roof. These lines correspond to the outer sides of the two posts on the other end of the arbor. Mark two perpendicular lines from the soffit downward, using a spirit level as a straight edge to keep the lines perfectly vertical.

Measure the distance between the two pencil lines. Cut 2-by-8-inch wooden beam to the length of this measurement. This is the ledger that bolts to the side of the porch under the eave. Cut two more beams 1 foot longer than the ledger. These are support beams that are bolted parallel to the ledger on the arbor’s posts.

Align the two longer support beams together on the wide side. Center the ledger on them and clamp them all together. The other beams will extend six inches beyond each end of the ledger. Make six evenly spaced markings on the thin edges of the beams. These markings will be the location of the notches that hold the cross beams. Two of the notches will be flush with the end of the ledger on each end. Therefore, the ledger will have only four notches and the other beams will have six. Unclamp the ledger and beams and draw notches 2 inches wide and extending four inches from the edge toward the middle of the beams. Using a jigsaw, cut out the notches.

Set the two posts for the other side of the arbor. If they will rest on a concrete surface such as a patio, bolt metal post brackets to the concrete, lining up the outer edges with the lines on the porch. Bolt the posts into the brackets. Check for vertical with a level and brace them in place with scrap lumber. If there is no concrete surface, dig post holes at least 2 feet deep and three times as wide as the diameter of the posts. Put 6 inches of gravel in the bottom, set the posts in the holes and fill in the holes with concrete. Brace the posts in a perfectly vertical position and lined up with the lines on the porch. Brace with scrap lumber until the concrete dries.

Hold the ledger board to the side of the porch under the eave and line up the ends with the pencil lines. Drill pilot holes every foot through the ledger and into the side of the porch. Insert a lag bolt into each pilot hole and tighten them with a ratchet.

Mark the sides of the two posts nearest the porch with a line the same height as the bottom edge of the ledger. Clamp two of the notched beams parallel to the ledger on either side of the posts with their bottom edges along the line. Line up their notches on the top edges with each other and with the notches on the ledger. The notches nearest the ends of the beams should line up with the outer edges of the posts. Check that the beams are level. Drill pilot holes through each beam into each post in at least two places with a countersunk bit. Screw the beams to the posts with stainless steel screws.

Cut six cross beams from 2 by 8 lumber using as the length the distance from the porch to the outer notched beam plus 6 inches. Notch one end of four of the cross beams from the bottom edge. The notch should be 2 inches wide and extend 4 inches from the bottom edge toward the top. Notch each cross beam twice on the opposite end to correspond with the notches on the beams screwed to the posts. If desired, cut a decorative curve in the last 6 inches of each cross beam.

Set the notched end of each cross beam into a notch on the ledger and into the notches on the beams at the other end. For the two cross beams without notched ends, seat them flat against either end of the ledger and set the other ends into the beam notches at the post sides. Screw the ends of the cross beams into the ledger ends. Now your arbor is connected to the front porch.