If a sofa has lasted 10 or more years it is probabley a good frame or it would have not lasted that long . good frames don`t wear out . most of the middle to low end furniture is plywood frames stapled togather .
Good frames are made of hardwood - oak, maple,ash,alder or mahogney . these frames are strong. the upholsterer can tell them by their weight. they are heavy . salesmen will lift a pice to show you have heavy it is . not anymore . with plywood and partickle bord a frame can be heavy and not as good as you might think.
a good upholsterer will check and re-inforce any weak joints and inspect it befor covering it.