I'm adding a room to the rear of our house; Mobile, AL, south exposure. Exist. roof is Tbr-line shingles, 4 yrs. old, essentially "welded" together as one layer. What is best way to separate the row where I have to add the new roofing under the shingles?
Note: new roof is only 1.5 on 12, so I've decided to use one-piece rubber roofing. More info if desired. Thanks!