Michelle, you don't need a stencil. Just a roll of blue tape and a chip brush. First, base coat the entire roof with a tan color. Start at the bottom of the roof. Tape off a row of shingles (5" or 6", or evenly divide the entire space so you end up with complete rows). Use the chip brush to dry brush light brown to med. brown paint just using an up and down motion from top to bottom. When dry, move the tape up to do the next row, add another piece of tape near the top of the first row, so that the second row overlaps as you brush top to bottom. Repeat up to the top. You can add some darker details by hand to indicate separate shingles along the rows. Add some shadows under the "lip" of each row.
Lynn Brehm
NATURAL-ACCENTS.COM