Sew A Box Cushion
Materials and Tools
- High density foam
- Measuring tape
- Sewing machine
- Steamer (or iron)
Step 1: Top and bottom
Measure from front seam to back seam and add 1". Measure from side seam to side seam and add 1". Cut 2 fabric sections to these dimensions. Fold each in half twice and steam press the creases.
Step 2: Boxing
Measure the length and the width of the cushion top. Add these 2 numbers together, then add 1". Measure the height of the boxing and add 1". Cut one section according to these measurements. This will be the front boxing strip. Repeat for the back boxing strip, but add 1-1/2" to the height to accommodate a zipper. If there is piping, stitch it all the way around the top and bottom fabric sections. Fold the back boxing strip lengthwise and steam press the crease. Fold the strip end to end and crease again. Cut along the lengthwise crease. To determine the zipper length, measure the length of the back boxing piece. Add 6" and round up to the nearest standard size. Stitch the zipper between the 2 halves of this strip. After the zipper is installed, stitch over the basted seam line on either end of the zipper. Sew the back boxing strip to the front boxing strip end to end to make a continuous round.
Step 3: Attaching the top, bottom and boxing
Slip the boxing over the bottom of the cushion with the wrong side out. Centre the seams of the boxing at the sides of the cushion. Mark each boxing corner with a vertical line. Remove the boxing and steam press at the pencil marks to make a fold at each corner. Align the centre crease of the boxing with the centre crease of the cushion top fabric section and pin at the corner creases. Open the zipper. Sew the two sections together. Repeat to sew on the bottom section. Turn the cover right side out.
Place the two sections to be joined right sides together and machine baste a 3/4" seam. Steam press the seam open.
With the wrong side of the fabric up, open the zipper and lay it fastener side down with the zipper teeth directly over the seam. Following the woven guideline on the zipper tape, hand baste the right side of the tape in place. Machine stitch directly over the basting stitches.
Close the zipper. Still working on the wrong side of the closure, baste the bottom ends and the remaining side of the zipper tape. Turn the fabric and zipper over, and working on the right side of the fabric, stitch over the basting along the bottom and the remaining side. Reinforce the top ends.
With small sharp-tipped scissors, snip the machine basting stitches that have kept the seam line closed during application of the zipper.
To determine the total amount of cord you need, measure each section to be piped and take the sum of all the calculations (see table below).
Buy the cord in a single length, and keep it that way, coiling it neatly on the floor as you sew on the casing. Do not cut the piping into pieces until you are ready to stitch it into a seam.
Yield 14 Running Yards
48 inches wide / 54-60 inches wide
5 yards / 6-1/2 yards
11 yards / 13 yards
22 yards / 26 yards
The fabric casing is made from strips of fabric cut on the bias. The diagonal seams minimize bulk when the piping is stitched into a slipcover seam.
Prepare the fabric. It is important that the grain is straight before you proceed.
Determine the width of your bias strips. If your cord is 1/4" in diameter, cut strips 1-5/8" wide. If your cord is 3/8" in diameter, cut strips 1-3/4" wide. If your cord is 1/2" in diameter, cut strips 2" wide.
Place the fabric wrong side up and make a diagonal fold. Cut along the fold. This is the true bias, and your guide for marking the cutting lines for bias strips.
With a yardstick and a pencil, mark parallel cutting lines from selvage to selvage according to the width you have determined in Step 2. Cut out the strips.
Place the ends of 2 strips with the right sides together. Stitch them together on the diagonal with a 1/4" seam. Steam press the seam allowance open. Repeat to create one long fabric strip; this will be the piping casing.
Place the casing strip wrong side up and lay the cord lengthwise down the centre. Fold the casing over the cord, align the raw edges, and pin the first few inches.
Adjust your stitch regulator to 4-6" (basting length). Using a zipper foot, stitch along the cord, staying as close to it as possible without sewing into it. Gently stretch the bias strips as you sew to make a smooth casing. This stitching creates a piping seam allowance.
Place one of the slipcover sections that is to be seamed with the right side up.
Align the raw edges of the piping seam allowance with the raw edges of the seam line of the slipcover section and pin. If you need to go around a sharp corner, notch the edges of the casing at the point where it will turn the corner. A softer corner is made by making several clips at the point where the piping turns the corner.
Cut the piping, leaving a 2" tail, and stitch the piping to the section along the casing seam line. Remove the pins.
Place the piped section and the other section to be seamed with their right sides together. Stitch along the seam line as close to the piping as possible, leaving a 2" gap for finishing.
Remove the stitches from the casing in the 2" tail. Fold the casing back, exposing the extra 2" of cord. Cut the cord so that it abuts the end of the other tail. Trim the extra casing so that 1/2" extends beyond the cord.
Ford the extra 1/2" of casing under the 1/4" and lay it over the abutting end. Slipstitch the edges together.
Place the sections with the right sides together and stitch the gap closed on the seam line.