Re: Sagging floors
Dana .... unfortunately there is no way anyone can say over the internet what is specifically required when it comes to structural support .... sight unseen.
Besides .... that's best left to a professional like a structural or in cases civil engineer. Likely your local building inspections department would likely need an engineer specify what is required before a permit is issued.
A recommendation is to contact an engineer to evaluate your situation and provide you with the solutions you require ..... the cost is not that outrageous.
Good luck with your project.
"" an ounce of perception -- a pound of obscure "