You save one of the walls.
Shed roof attached to house.
However if you choose to build a freestanding shed and use this style of roof you should plan the slope of your roof in such a manner as to slope down from the front to the back of the shed.
If you are tying the shed roof into an existing roof on the house you will need to remove the shingles and sheathing to expose the roof framing.
More often than not attached shed use lean to roofs because they are easier to build and allow water snow and all that stuff to drop easily instead of trooping between the shed roof and your house wall.
A house attached patio roof takes advantage of the house s structure by supporting one end of the roof on a ledger mounted horizontally to the house.
Depending very much on specific small house design its proportions and weather conditions of the location.
The ledger typically a 2 by 6 is usually designed to hold one end of the patio roof rafters.
The ledger should be attached before the foundation is built for a deck patio roof posts and other structure.
The roof is typically sloped down from the connecting wall if the shed is attached to the side of your house or garage.
Work from the height of the outside of the new shed roof.
Locating and mounting the ledger is normally a fairly easy process.
Rafters should be attached to the header beam using hurricane ties.
You will need to attach the porch rafters to the house roof rafters and replace the roofing and flashing.
If the outside edge is 8 feet high and the area being covered is 15 feet attach the shed roof addition at least 9 feet 3 inches above the level of the porch or other area being roofed or 10 feet 6 inches for a 2 pitch.
A shed roof should slope at least 1 inch per foot but 2 or 3 inches will be better.