Making a cushion cover is a great way to change the look of a chair, and being able to remove the cover for washing will keep it looking fresh for a long time. The best way to do this is by inserting a zipper. This cushion cover has a band that goes around the sides of the cushion. The zipper is inserted at the back.
Measure the length, width and depth of the cushion.
For the top and bottom of the new cover, cut two pieces of fabric each 3/4 inch bigger than the cushion.
For the side and front edge, cut a strip of fabric 1 inch wider than the depth of the cushion and 2 inches longer than the total length of the front and two sides added together.
For the back strip, cut two pieces of fabric as long as the back of the cushion plus 1 inch. To determine the width of these two pieces, do the following: Divide the depth of the cushion in half and add 1 inch to each piece. For example, if the cushion is 3 inches deep, cut two pieces each 2 1/2 inches wide. (Three inches divided in half equals 11/2 inches, plus 1 inch equals 2 1/2 inches.)
With the right sides together, sew the long edges of these two back pieces together. Sew the first and last 11/2 inches of the long edges and then baste the remaining middle section. Press the seam open. Lay the zipper face down over the basted seam. The zipper tab will be facing outward. Pin the zipper in place and sew close to the zipper teeth up and down both sides, and across the bottom and top of the zipper. Remove the basting stitches.
With the right sides together, sew the short ends of the back, zippered piece to the short ends of the long-edged piece. (You have created one loop.) Open the zipper.
With the right sides together, pin the top of the seat cover to one long edge of the edge piece. Sew it in place, spacing evenly and easing around corners. Repeat with the bottom of the cover. Turn the cover right-side out. Squeeze the cushion and work it into the new cover.
Unless otherwise indicated, all seams are 1/2 inch.