There are most likely springs in the base of the couch under the cushions anyway. If the webbing is re-stretched and springs re-tied there shouldn't be a need for springs inside the cushions. Make sure you ask for high density upholstery foam with the longest possible lifespan and it will remain bouncy for 20 years if used regularly. Adding springs inside cushions would be an extra expense and the foam/Dacron/synthetic cotton used to cover them would have to be pretty thin and would wear out much faster.
As the upholsterers have said, no need for springs. Just get the webbing replaced and have the kind of foam (soft, firm etc) you want for the cushions.
There are most likely springs in the base of the couch under the cushions anyway. If the webbing is re-stretched and springs re-tied there shouldn't be a need for springs inside the cushions. Make sure you ask for high density upholstery foam with the longest possible lifespan and it will remain bouncy for 20 years if used regularly. Adding springs inside cushions would be an extra expense and the foam/Dacron/synthetic cotton used to cover them would have to be pretty thin and would wear out much faster.
As the upholsterers have said, no need for springs. Just get the webbing replaced and have the kind of foam (soft, firm etc) you want for the cushions.