If your sofa is beginning to sag or is sinking in certain spots, you can strengthen the support frame before it breaks without having to hire a professional furniture repair technician. Because sofas and chairs are generally built on a wood frame and covered in upholstery, you can reinforce the frame rather than replacing the entire piece of furniture. Strengthening the support of your sofa can be done by enterprising homeowner.
Take the cushions off your sofa and pull it away from the wall.
Turn the sofa over to expose the bottom. Pull the mesh covering the frame away by pulling out the staples holding the mesh cover in place using a staple puller.
Measure a side of the exposed wood frame with a tape measure, then measure and mark a 2-by4-inch lumber beam to cut to the same length.
Put on safety glasses and cut the 2-by4-inch lumber beam to size using a circular saw.
Run a bead of glue along the wood frame in the sofa, then press the cut 2-by4-inch lumber beam against the glue. Hold in place for about two minutes.
Hammer six to eight spiked wood joiners into the new lumber through to the old frame to attach it.
Repeat Steps 3 through 6 as necessary to strengthen the rest of the wood beams in the sofa frame. Then staple the mesh back into place to cover the frame.
Turn the sofa upright, put it back into place, then replace the cushions.