Hand Hune Floor Joists

[ManchesterHome]

Hello everyone! I recently bought an old 200 year old farm home in the country. It is the definition of paradise. I bought the home knowing its challenges and decided to move forward anyway. The floor is settled and very uneven. From corner to corner there is a 4 inch drop at the edge of the kitchen. I would like to level this floor and put in a hardwood floor eventually. The home has a basement and the foundation has been updated with block. The floor joists are actually hand hune logs which the pine slats in the kitchen rest on. Quite a few of the boards sag when we walk on them so we once thought to level the floor by using different thickness of plywood until feathering the sizes out to level the floor. I had a couple contractors out to give estimates and this was one of the methods the first contractor suggested. The second, suggested tearing out the entire floor, removing the timber logs that support the kitchen, and then installing new joists and starting fresh. The second contractor stated that it was an easy job but time consuming because of the layout of the home and the basement. So, my questions to the DIY community is this; If I wanted to tear out the old floor, and start over with new, how do I tie in the new floor joists? Do I simply use the existing foundation and main support beam and tie in the new joists? Can I safely remove the logs that support the floor without the house falling in? By looking up from the basement it appears that it could be just that simple/complex.

I've replaced floors, and removed and replaced floor joists in the past. Never on something this old or this type of construction. I am a bit intimidated but really like the idea of starting over with a new level floor. I would say that my experience and craftsmanship level is above average and I would be comfortable taking on this project if I would not be required to jack up the house for more support. The home appears to be a solid build and I hope you guys can shed some light on an easy way to proceed. Opinions and suggestions wanted!

The picture is a shot from the basement. It shows the foundation wall and the main support beam (dunno the correct term) and the logs that tie in. The kitchen floor is directly above the log shown. The wet stain you see in the picture was from a previous leak in the kitchen before the home was bought. It is dry.