We are planning to add a room addition and a small porch to the rake ends of our gable-roof house. What is the best way to attach the roof to the existing house? (There is a 2' overhang on all sides of the current roof.) Is it better to drop down a foot or so & start a new roof line than try to blend into the existing roof? (Shingles aren't an issue, since we'll be getting a new roof over all.) Do we need to cut off the overhang so we can frame directly to the gable truss? Also, should we remove the existing siding to attach the framing to the studs, or can we go over the existing T-111 and 1" insulation board? I've looked in several books, but haven't seen a good description of how this is done. Any help will be most appreciated!

You don't provide enough detail about the size and height of the addition nor the roof type.

Typically, siding need sto be removed to properly fasten and add support for new walls.

Sorry, I didn't realize that mattered. The addition will be about 18' wide (along the existing house side, which is about 30' wide) by 24' long. The roof is an asphalt shingle over plywood type. The porch will be about 19' wide by 7' deep, with one end enclosed for storage.

yes the overhangs do need to be cut back.the additin needs to be attatched to framing members and not just to the siding so areas will need to be removed and framing will need to be added.it is best to match roof lines an addition is not supose to look like an add on it should look like it allways existed.
Tim; Rock Creek contractor service inc.

sue, it sounds like your addition will be smaller than the width of your existing structure. If this is correct, it may look better to drop your roof line lower than your house. If you do want to tie into the existing roof line it is very important to make sure that you get the correct pitch of the roof before ordering trusses so that everything planes in like it should. If money allows you may want to have a drafts person make a couple of drawings to show some different roof lines to determine the look you desire before starting your project. Good Luck!

Sue:Is this a 1 or 2 story house and do you want the floor height to be the same as the house. Remember the wider the addition you add, the less height you have on the outside of the addition. To keep your room height you might have to lower your floor, or attach into your existing roof higher, and also apply a different pitch. ( There are pitch requirements for your area, check your zoning codes)

Thanks for your input. My house is a one-story. The addition will be added to the gable end. It will be about 18.5' wide, whereas the house is 30' wide. So it will follow the existing roof line for 9.25 feet at the front, then turn down for the other half. My question is what is the best way to connect the new rafter to the existing house. The house has trusses, but I'm planning to use rafters on the addition. Do I remove the existing T-111 siding and attach the new rafter to the gable truss? Or is there a better way? I'm doing the same thing with a small porch on the other gable end, so I'd really like to get this figured out. I can't find anything like it in all the framing books I've looked at, but it's a very common design with new construction. I do want the floor level to match the existing one, and the pitch will be the same (5/12). Any help will be most appreciated.

I don't think it's necessary to attach the new rafter to the existing truss at all. Just frame the first rafter right next to the truss. Because of the different construction types. I would rather not try to continue the roof line, but I would drop the new roof slightly, maybe 8 inches. This will avoid problems from different settling rates or deflections, and also avoid a little bump in the roof where the new and old meet. That might mean your side wall will be 7'-4" high if the existing house is 8 feet high, and you would have a short slope inn the ceiling just above the wall.