Using a board of plywood is a great quick fix to your sagging couch if the frame is weak or broken. Keep in mind though, that it's more of a temporary fix and you will need to fix the actual frame later. Plywood adds support for the cushions but it makes them a lot firmer too. This might be not what you want. Therefore, it is ideal for ensuring the cushions remain rigid without sinking or sagging on the couch. To install, simply unzip the cushion covers and stuff the fiber or batting under the existing foam cushion. Zip the

suggestion:

couch sinking fix
couch sagging fix as seen on tv
couch cushions sinking fix
how to fix sinking sofa