Despite the name, the shed roof is not used just for sheds. That style is a frequent choice for any addition to a house from a garage to a porch to a room. A shed roof slopes in only one direction, which simplifies its construction. Shed roofs may be covered with shingles matching the house, corrugated metal or vinyl, or even a flat roof membrane or similar material if the slope is very low. Some shed roofs are almost flat. A shed roof's top is attached to the house.
Identify the area on the house's side where the shed roof will attach. Mark the outside edges and basic height on the house wall with a marker. Locate the studs or base plates inside the wall. Find some structural element strong enough to bear the weight of the shed roof. Use a band or rim joist between the levels of a two-story house or the double wall cap boards on a one-story. Use a stud finder, which locates nails in studs, or look for stud nails on the wall. Find one stud and measure 16 inches apart to locate others.
Remove the siding from the wall with a pry bar or similar tool to attach a 2-by-6-inch ledger board that supports the shed roof framing. Take off enough siding allowing for installing metal flashing between the house wall and the ledger board. Mark the correct height for the roof attachment on each end of that space using a tape measure and snap a level chalk line to mark the bottom of the ledger board.
Cut the ledger board with a circular saw to the correct length. Level it with a level and nail it temporarily in place. Drill pilot holes with a power drill through the ledger board into the wall studs, band joists or other structural members. Put the holes every 16 inches, which is stud spacing.
Drive lag bolts with pointed screw ends through the ledger board into the structural members. A ratchet wrench fastens the bolts with washers under the bolt heads allowing space for water drainage. Make sure the ledger board is secure and solidly connected.
Install metal flashing up the wall's side and over the ledger board's top. Put metal rafter hangers on the on both ends of the board and every 24 inches between holding the shed roof rafters. Replace the siding above and around the ledger. Frame the roof with rafters, decking and covering once the ledger is firmly attached.