There was a sagging spot in the middle of our hallway. We pulled up the carpet and found this.
A large hole. The floor had caved in.
I put my best men on it.
But only one was allowed to use the power tools.
As the flooring was cut, we discovered the cause of all the problems. The furnace was leaking, and ready to fall through. We ended up replacing half the hallway, and securing the furnace.
We put down plywood instead of replacing it with particle board. We also discovered that some one before us had replaced the floor. Why they didn't put down plywood I will never know. The replacement floor was done with everything we already had on hand.
Nothing was bought in town.
Next step is to put down the hard wood flooring that we got at auction.