We own a 1974 home in Fishers, Indiana. Our home is on a crawl space. The 2x8 floor joists are 16-inches o.c. and a crawl space contractor has proposed installing jacks at 8'-0" to level the joists using a 4x6 purlin to beef-up the support of the floor which sags some and generally seems weak. They also propose insulation, plastic vapor barrier, sealing the louvers, and opening the duct to "treat" the air in the crawl space. I think this is probably a good idea to do. "Modernizing" the crawl space seems like a good idea.
I was investigating the floor in the foyer and discovered what I consider a hot mess. We appear to have 3/4" plywood over the joists, then a layer of luan. Then there is a layer of vinyl floor. Then there is another layer of luan and another layer of vinyl. Then there appears to be a parquet floor that is loose. Then there is a layer of foam barrier. Finally, there is a pergo floor system on top. I hate the way it sounds.
That's an amazing amount of floor to be installed over 36-years (and left in place) in my opinion. Nonetheless, should I strip the entire floor down to the plywood when I work on this home? The front door can barely clear the floor when I open it. It's not possible to put a matt down. Still, could it be that this extra dead-load has been adversely affecting the 2x8 joists which I understand to be undersized???