How to Add a Porch Frame to the Side of a House

Select a place on the house wall to attach a porch addition. Find a place with a band joist or other house framing sturdy enough to support a porch frame. Measure the width of the porch with a tape measure and mark the ends on the house wall. Measure the height desired and install piers to support the outside frame of the porch.

Set piers in place, one at each outside corner and no more than 8 feet apart, if the porch addition is large. Use pre-cast concrete piers with metal brackets attached to hold the porch framing. Dig holes with a posthole digger a foot or two deep to hold the piers. Stretch a string between the top of each pier and the attachment point on the house and use a line level to level it as a guide for framing.

Attach a 2-by-6-inch or 2-by-8-inch ledger board to the house wall, the width depending on how big the porch will be. Remove any siding in the area and identify joists or other fastening points on the wall; mark those on the wall sheathing. Nail the ledger board in place temporarily with 16d framing nails and a hammer. Use a level to get it level.

Drill pilot holes through the ledger into the wall framing with a power drill and 3/8-inch bit. Fasten the ledger with 1/2-inch lag bolts, which have a screw end and a bolt head long enough to penetrate the wall sheathing and at least 1 1/2 inches into the framing. Drive bolts in with a ratchet wrench.

Build a porch frame with 2-by-6-inch or 2-by-8-inch boards. Nail end boards to side bands with framing nails. Square it by measuring corner to corner to get the diagonals identical. Set the frame sides into the metal brackets on the piers. Secure them with 2-inch galvanized screwsand a screw gun. Fasten the end band to the ledger with 3-inch galvanized screws.