Remove the cushions from the sofa and set them aside.
Cut the fabric on the seat of the sofa, down across the back and down the two arms, as close to the frame as possible. Flip the fabric and any padding back to reveal the springs. The springs on a modern sofa are usually zigzag wires, called sinuous springs, installed with a slight arc from the back wall of the sofa frame to its front edge.
Remove any broken springs or any springs that no longer arc upward by pulling the nails that affix the spring clips to the frame, using the back of a hammer.
Measure down the length of the couch, from arm to arm, with a measuring tape. For a standard 72-inch sofa, you need 15 lengths of springs. Before cutting the springs, sold in 10-foot lengths, determine how much arc you want in the springs. The higher the arc, the more give the seat of the sofa has. For a relatively stiff seat that you don't sink into when you sit, keep the length of the springs close to the measurement from the inside edge of the front wall of the sofa frame to the inside edge of the back frame.
Nail a clip to the front and back edge of the frame every 4 3/4 inches on the center of the clip with barbed upholstery tacks or nails, starting 2 3/4 inches from one sofa arm and ending 2 3/4 inches before the other arm.
Cut the springs to the appropriate length with bolt cutters, ensuring that you make the cut just before the spring wire bends, so you have a straight piece to fit into the clip. According to upholstery supply company PerfectProductsOnline.com, if you count seven loops down the right side of a 9-gauge spring, you have 1 foot of sinuous spring.
Slide the end of a spring through the channel of a clip on the back of the sofa frame. Pull the spring toward the front clip and slide the end into the channel of the front clip. Repeat for every spring across.
Nail four nails into the wood of the sofa frame surrounding the springs -- two pairs, opposite one another on each of the arm sides of the frame. Nail one pair 6 inches from the front edge of the sofa frame and the other two nails 6 inches from the back edge of the sofa frame. Leave the nailheads slightly raised from the sofa frame.
Wrap twine around one nailhead and tie it in a knot. Pull the other end of the twine straight across to the first spring; the twine should be perpendicular to the sinuous springs. Tie the twine to the spring with an overhand knot, keeping the twine taut between the nail and the spring. Pull the twine across to the next spring and tie another knot. Repeat all the way across, tying it off and cutting the twine from the ball at the other nail. Repeat between the other pair of nails.
Pull the padding and fabric back over the springs and smooth them into place. Staple the fabric back in place with a staple gun.
Put your cushions back in place.
Things You Will Need
- Utility knife
- Measuring tape
- 9-gauge sinuous spring
- Bolt cutters
- Spring clips
- Barbed nails
- Ball of twine
- Cushions can be restuffed with new foam to restore their firmness.