To determine the amount of fabric you’ll need, measure the chair, including the cushions; allow 1 inch for seam allowances and 6 inches for tuck-ins where the arms and back meet the seat. When possible, try to get two narrow sections from one fabric width. Plan extra fabric if you’re making a skirt or matching a print.
To allow for covering cord, add an extra 1 1/2 yards of fabric. Approximate yardage for a wing chair is 7 to 9 yards: for an occasional chair, 4 to 6 yards; for a club chair, 6 to 7 1/2 yards. To calculate how much cord to buy, measure all the seamlines.
If there’s an existing slipcover, consider cutting it apart to use as a pattern. Otherwise, drape the fabric on the chair, right side out, with the lengthwise grain matching the former chair’s grain. Work from the top to the bottom and from the center out, smoothing the fabric and pinning along the upholstery seams with T-pins.
Cut out the pieces, allowing for seams and tuck-ins. Add extra seam allowance at the back of a cushion for inserting a zipper and at the chair bottom. Clip seam allowances at corners and inside curves. Before removing the fabric, spread the seam allowances open; mark the seamlines with dressmaker’s chalk. Remove and label all pieces.
Sew the sections together with piping in the seams. Make gathers, tucks, or pleats to control the fullness on a curve.
Insert the zipper in a side back seam; it should extend at least three-quarters of the seam length. Open the zipper. Place it face down on the seam allowance that holds the piping with its teeth next to the covered cord and its stop 1 inch from the bottom seam-line. Stitch. Close the zipper. Turn under the other seam allowance and stitch the zipper to it. For a cushion, insert the zipper by the centered method, extending it across the back and into the sides.
Put the slipcover on the chair; mark the bottom seamline. Attach a skirt or facing. Tack the seam allowances or facing to the underside of the chair. Or attach two 12-inch lengths of twill tape to each corner of a skirted slip-cover; tie the corners to the chair legs.