I am selling my home and want to do the repair to the roof decking without spending a fortune. I was wondering is there a way to replace the rotton wood that hangs over the edge of the roof without replacing the entire roof? I had someone look at it, and they said because a roof is shingled from the bottom up (asphalt shingles) you would have to take the whole thing off to get to that rotton wood. Is this true? Is there a way around it?

No, not true. You can replace just the lowewr section but you must carefully remove the shingles with a tool. The tool is as thin as a butcher knife and has a small notch that slides up under the shingle and snags the nail. It is likely you will loose a few shingles in the process.

You can also use a 'shingle bar', it is flat on one end,right angled on the other end,specifically made for the removal of embedded shingle.

ANY roofer worth his salt would know this tool and would not suggest tearing the entire roof off as ballengerb1 suggested.

To replace the roofing from the bottom you need to remove the area affected(overhanging area) then removal from this area down isn't any more than pulling nails and typical repair work, but the initial removal requires a little skill in the field.

A local handyman,or another roofer might be your best interest.

Ken