Roofs that have slopes of 4:12 or less are considered to be low slope roofs.  (4:12 means a vertical rise of 4 inches for every 12 inch horizontal run, or 18.4°). Never apply asphalt shingles to slopes that are below 2:12 (9.5°).  Shingles applied on low slope slopes do not last as long as shingles on steeper roof pitches, due to the increased exposure to sunlight and other weather conditions.  Generally, laminated/architectural shingles are better suited to steep roofs, and do not offer aesthetic benefits when applied on low slopes.