Sofas are one of the most expensive pieces of furniture purchased for a household. Choosing a sturdy sofa with quality workmanship will result in years of service. Over time, even the best of sofas need repair. Fix popped seams, rips and sagging cushions at home without the need for professional, expensive repair services. Most fabric or upholstered sofa repairs can be accomplished with minimal sewing skills and the ability to operate an iron and/or an electric kitchen knife. To avoid further sofa damage, have leather sofas repaired by professional leather workers.
Fold under 1/4 inch of the edges on each side of the popped seam. Pin the edges together with straight pins. If your cushion is upholstered in a woven fabric and the edges are frayed, apply a fray-stopping solution to stiffen the fabric edges. Keep this close to the edge of the fray so the solution doesn't interfere with your sewing.
Thread an upholstery needle and tie a tight knot at the end of the thread. According to Craft: Transforming Traditional Crafts website, in the article, "How to Mend Torn Upholstery," upholstery needles are curved to assist in easier sewing for flat surfaces. Upholstery needles are often sold as mattress needles.
Insert the needle near the end of the popped seam. Sew two stitches before beginning the seam repair. Sew the edges together using a whipstitch (see Resources for whipstitch illustration). Remove the pins as you sew. When you get to the end of the seam repair, sew two stitches backward along the seam, and then sew two stitches forward to lock the stitches.
Unzip the sofa cushion cover and remove the cover from the cushion. Turn the cover inside out.
Measure the width of the rip. Add 1 inch to this measurement. This is the modified width of the rip. Measure the length of the rip. Add 1 inch to this measurement. This is the modified length of the rip.
Measure and cut an iron-on fabric patch according to the modified width and the modified length measurements. Iron-on fabric patches are available at discount, craft and fabric stores.
Insert the sofa cushion cover over the ironing board with the ripped section centred on the board. Pull the edges of the rip together. Snip away any loose threads.
Set the iron on the highest heat setting, normally the cotton setting. Iron the rip and the surrounding fabric. According to The Moritz Embroidery Works website, in the article "Easy Iron-On Patch Tips," this warms up the fabric where the patch will be applied for a more effective bond. Hold the iron onto the fabric for about 10 seconds.
Center the iron-on patch over the rip with the adhesive side touching the rip. Iron the patch onto the interior of the cover, pressing down firmly, for about 10 seconds or according to the duration recommended by the patch manufacturer. Turn the cushion cover right side out. Replace the cushion cover over the sofa cushion.
Place the current foam or sponge cushion insert on top of the new sponge or foam. Use a marker to trace around the current cushion onto the sponge or foam with a marker.
Cut the sponge/foam along the traced outline. According to Upholstery Supplies Guide, use an electric kitchen knife to cut the foam or sponge. If necessary, new blades for the knife can be ordered from the company. Some fabric stores will cut the sponge/foam to your measurements if you purchase the sponge/foam at their store.
Insert the new foam/sponge cushion into the sofa cushion cover and zip close.
If your sofa cushion doesn't have a zipper, you will need to pop the back seam with a seam ripper to remove the sofa cushion, and then resew the seam. To fix just a sagging corner, stuff polyester or cotton stuffing into the corner until the cover fills out.