A relaxed cushion style is the waterfall edge, also called bull-nosed cushions. While other cushions have crisp seams or piping around the edges, a waterfall-edge cushion is constructed in such a way that the fabric runs smoothly over the front edge and drops around to the underside without a seam along the face of the cushion. Typically seen on patio cushions and boat cushions, the waterfall-edge cushion seam can be used anywhere in and around the home for a casual feel to your furnishings.
Measure the length of the foam from front to back, the width from side to side, and the height or thickness. Cut two side pieces of fabric that are the foam’s length plus 1 inch by the depth plus 1 inch. Cut two end pieces of fabric that are the foam’s width plus 1 inch by depth plus 1 inch.
Fold the two end pieces in half lengthwise with the pattern of the fabric facing out. Pair the two pieces side by side with the folded edges running down the middle. Sew a zipper that is equal in length to the foam’s width to the folded edges to form the back panel. See the Resources section if you are unfamiliar with sewing a centered zipper.
Multiply the foam’s length by two, and add the depth to this measurement. Cut one piece of fabric to this length plus 1 inch by the foam’s width plus 1 inch. Spread this piece of fabric out onto a flat surface with the pattern facing up and the width running vertically.
Align a length edge of one side piece to the body piece starting at a corner with the pattern facing down. Pin the edges. Turn the side piece to align the adjacent width edge along the middle of the same long edge of the body fabric, and pin the edges. Turn the side piece one last time to align the other length side with the remaining length of the body piece, and pin to form a box shape.
Sew along all three pinned sides with a 1/2-inch seam. Repeat Steps 4 and 5 to attach the other side piece along the other side, and sew to complete the cushion shape with the exception of the back.
Align the four sides of the zipper panel with the four open edges of the cushion fabric with the zipper facing in. Pin the edges, and sew down all four sides. Open the zipper, and turn the cushion cover right side out. Insert the foam into the cover, and zip the cover closed.
Use a fabric that is suitable for where the waterfall cushion will be, such as a cotton home décor fabric inside or a waterproof vinyl fabric for outdoor use.