Hi Roger, It sounds like you have a "Hip" roof from your description. This type of roof has four sides and slopes in all four directions. To measure a hip roof, just remember some basic geometry. First, draw the roof on a piece of paper as viewed from above, looking straight down. Now, divide the roof area into a series triangles and rectangles. Next, figure the areas of each piece applying basic geometric principles. The area of a triangle is obtained by multiplying two sides and dividing by two. The area of a rectangle is determined by multiplying two adjacent sides. You will need to get on the roof and measure lengths to apply to your drawing, and because of the attached garage, will have many triangles and rectangles to add up, but this way will be accurate for you. Just remember to add 10% as a waste factor for cutting and fitting, etc. Good Luck.