How to Fix Sagging Couch Cushions (Quick Fixes and Permanent Ones)

A sagging couch is one of the most common furniture complaints. You sit down and sink further than you used to, or the seat has a dip where everyone always sits. The good news is that most sunken couches can be fixed without buying a new sofa. The trick is working out what is actually sagging before you spend any money.

Why couch cushions sag

There are two main causes, and they need different fixes.

• The foam has broken down. Every foam cushion softens with use. Lower-density foam loses its shape faster, and the spot you sit in most goes first. Signs include a permanent dent, a cushion that feels thinner at the front edge, or foam that crumbles or feels soft and limp when you squeeze it.
• The frame, springs or webbing have given way. Under the cushions, most couches have a deck held up by sinuous (zigzag) springs, coil springs or elastic webbing. Springs can bend or come loose from their clips, and webbing stretches over time. When that happens, even a brand-new cushion will sink.

Less often, the problem is the cover. A cover that has stretched or bagged out can make a fine cushion look saggy.

How to tell if it's the foam or the frame

1. Take the cushions off. Look at the deck. Press down with your hand in several spots. It should push back evenly. A soft spot, a visible dip, or a spring that has popped out of place points to the frame.
2. Look underneath. Tip the couch carefully and check for broken webbing straps, loose spring clips or a cracked rail.
3. Check the cushion on a flat floor. Lay it on a hard floor and look at it from the side. If it has a dip or is noticeably thinner in the middle or at the front, the foam is worn.
4. Swap cushions. Put a rarely used cushion in the saggy seat. If the seat still sinks, it's the frame. If the dip moves with the old cushion, it's the foam.

Many older couches have both problems. Fix the frame first, then judge what the cushions need.

Quick fixes for a saggy couch

These are low-cost, same-day fixes. They won't bring tired foam back to life, but they can buy you time.

1. Flip and rotate the cushions

If your seat cushions are the same on both sides, flip them and move them between seats. This spreads the wear and can even out a mild dip. Make it a habit every week or two.

2. Put a board under the cushions

For a frame that has gone soft, a piece of 1/2 to 3/4 inch plywood cut to fit the seat deck adds firm support right away. Sand the edges and wrap it in a thin layer of batting or an old blanket so it doesn't rub the cushions. This works best as a stopgap. It makes the seat firmer, and it doesn't repair the springs.

3. Add batting or Dacron to the cushion

If the foam is only slightly flat, unzip the cover and wrap the foam in a layer of polyester batting (often sold as Dacron). This fills out the cover and softens the edges. It adds a little loft, but it won't restore firmness to foam that has broken down.

4. Repair the webbing or springs

Stretched webbing can be replaced with new upholstery webbing and a staple gun. Loose sinuous springs can often be reattached with new clips. If a rail is cracked, or you're not comfortable with the repair, an upholsterer can usually do it for less than the cost of a new couch.

The permanent fix: replace the foam

When the foam itself has worn out, no amount of flipping will bring it back. Replacing the foam gives you a seat that feels like new and keeps the couch you already like.

You have two options:

• Foam only. If your covers are still in good shape, order replacement couch cushion foam cut to the size of your covers and slide it in. You can compare grades in our custom foam collection.
• The whole cushion. If the covers are faded, stretched or stained, order complete replacement couch cushions with new foam and a new cover made together.

Not sure which way to go? Our guide on whether to replace the foam or the whole cushion walks through the choice.

Choosing foam that won't sag again

Density and firmness both matter. Density (pounds per cubic foot) is a good guide to how long foam lasts. ILD measures how firm it feels. Here is how our options compare:

For seats, choose Lux foam. On its own it gives a firm, supportive seat. If you like a little more give on the surface, add the Dacron wrap. Super Soft is too soft for seat cushions and will bottom out, so keep it for back cushions.

Lux foam typically lasts 5 to 8 years, depending on how much the seat is used.

Measure carefully before you order

New foam only fixes the sag if it fills the cover properly. Measure width, depth and thickness at the seams, not the crowned center. Our step-by-step guide on how to measure couch cushions covers T-cushions and odd shapes. Every order comes with a spec sheet for you to approve before any foam is cut.

Frequently asked questions

Can you fix sagging couch cushions without replacing them?

Sometimes. If the frame is the problem, a plywood board or a webbing repair can solve it. If the foam is only a little flat, flipping, rotating and adding a batting wrap can help for a while. Foam that has broken down needs to be replaced.

Does putting plywood under couch cushions work?

Yes, as a short-term fix for a soft or sagging deck. It makes the seat firmer straight away. Wrap the board so it doesn't wear the cushions, and plan a proper spring or webbing repair if the couch is one you want to keep.

How do I fix a sunken sofa in one spot?

Swap that cushion with one from a less-used seat and see whether the dip moves. If it does, the foam is worn. If it stays, the springs or webbing under that seat need attention.

What thickness should new seat foam be?

Match your current cushion, measured at the side seam. Most seat cushions are 3 to 5 inches thick. Our builder goes up to 8 inches if you want a fuller seat.

Will firmer foam stop my cushions from sagging?

Higher density foam holds its shape longer, which matters more than firmness alone. A 1.8 lb density foam like our Lux grade is a good choice for seats that get used every day.

If your cushions have gone flat and the frame is solid, new foam is usually the simplest way to get your couch back. You can enter your measurements in the foam builder and see the price instantly, or email care@fabricakraft.com if you'd like help choosing.