Why Is Your Couch Sagging? How to Fix It With a Spring Kit

If you sit down and feel like you're sinking through to the floor, your first thought is probably "time for a new couch." Check the springs first. A sagging cushion is almost always a spring problem, not a sofa problem, and it's one of the easiest upholstery repairs to do yourself, even if you've never done one before.

What's Actually Happening Under Your Cushion

Most couches support each cushion with a row of coil springs, held in place by clips and a length of wire running along the top of the row. The stay wire does two things: it keeps each spring from leaning or shifting out of place, and it ties the whole row together so your weight spreads across all the springs instead of just the one you're sitting on. When a spring stretches out, pops loose from its clip, or snaps, that support drops out from under one spot — which is why sagging usually shows up as an uneven dip rather than the whole cushion collapsing at once.

You're replacing a handful of small parts here, not rebuilding the couch.

How to Tell What You're Dealing With

The most reliable way to know is to look directly: pull off the cushions, or flip the couch over, and check the spring deck itself (you may need to pull back the dust cover which is the black fabric on the bottom). From there it's usually obvious — a spring that's popped loose from its clip, bent, or snapped needs replacing. If what you find instead is webbing (a woven fabric strap) rather than individual coil springs, that's a different repair, covered below.

Don't want to flip the couch or open up the dust cover just yet? A couple of signs can point you in the right direction without looking underneath:

• One spot gives way more than the rest when you sit → likely a single failed spring
• You hear a creak or metallic ping when you sit → a spring has probably popped off its clip

These aren't as certain as looking directly, but they're a good starting point before you order parts.

What You'll Need

• A spring replacement kit, sized to match your couch
• Stay wire if your kit doesn't already include it
• A screwdriver, pliers, and a tape measure

Measuring tip: springs are sold by length: 15", 18", 23", 25", 27", and 31" are common. Measure an existing, still-good spring top to bottom before ordering, and check two or three across the row; the springs aren't always identical front-to-back.

How to Replace a Sofa Spring

1. Pick your access route: flip the couch over and pull back the dust cover (the black fabric on the bottom), or remove the cushion and pull back the seat deck — the fabric platform the cushion rests on. On most furniture, either layer is just stapled to the frame, so you can lift an edge and re-staple it when you're done. If the layer you're working with is sewn instead, the other route is usually easier.
2. Remove the damaged spring — the clip is screwed into the frame, so unscrew it and set both the old spring and old clip aside. You won't reuse either.
3. Screw one of the new S clips included in your kit into the frame.
4. Hook the new spring into the clip, matching the coil direction of the springs beside it, then run the stay wire back through the top of the spring the same way the original was routed and attach it with one of the wire clips included in your kit.
5. Press down by hand to check the tension matches the springs next to it.
6. Re-staple whichever layer you opened. If it's the dust cover and it's torn, swap in a new dust cover instead of reusing the old one.

If It's Actually the Webbing, Not the Springs

Some couches, especially older ones, support the cushion with woven elastic webbing instead of (or underneath) coil springs. If the springs themselves look fine but the seat feels loose or you can feel the frame through the fabric, a webbing replacement kit may be the fix, not a spring kit. Same idea, different part.

Ready to fix it? Shop upholstery spring kits sized for your couch.