Sounds like a good plan to me!
I don't know where you live, but if tornados are possible in your area you might think about a small steel shelter under the floor while you're at it.

Well, that could be an awful lot of work. How big is the space? If you had a 5" dip in the middle of the room, and it was a gradual dip, you'd have to be sistering or notching most of your joists, I think your idea has alot of merit, but I wouldbe leaning towards a major "sistering" project, I think. Knowing alot about an 1840s floor and very little about sistering, I think that once you had ripped off the floor, you could do your laser level idea with all new joists sistered to the old ones. More money for the joists, but still a DIY kind of project.

"do your laser level idea with all new joists sistered to the old ones."

This is the way to go. Use your laser level now, however, to see how much the floor will be raised around the room. If one lower corner of a wall is going to wind up several inches higher than the other lower corner, the wall may look distinctly odd / unsquare. The appearance of the ceiling may be an issue as well, if it is not level now. If so, you will have to decide if it is something you can live with. Better to know ahead of time.

If 5" out of whack and you are determined to do this, then why bother removing the floor? Just lay a new floor over the one you have with sleepers cut for the correction and nailed over the joists in the crawl space?

I would also be careful when cutting the last joist bay out (the side running with the joist, not across) as you do not want that wall to "bulge" and collapse. The floor boards help keep that wall straight (I won't say square...)

Check your ceiling too, If it is out of square with the floor and you correct the floor, it might look really silly.

We had a similar problem in the upstairs bathroom (5'x16') of our 1906 farmhouse-- the space had originally been an outside deck/porch, and the owners decided to close it in to make a bathroom... however, the floor was (wisely) sloped away from the house and dropped almost 4" across the 5' width of the room, and when they converted it into a half-bath, they never bothered levelling the floor. (They DID, however, carpet the heck out of it, many times over-- but that's another story!)

Needless to say, a toilet on an unlevel floor is a stupid idea... within months of us moving in, the toilet developed a leak at the floor, so we were basically forced into remodelling the whole room, which we did entirely DIY.

When we pulled up the floorboards, we discovered that the floor joists were spaced really wide apart, like 3'... so we created "ladder" inserts for each of the sections, using 2x6's-- basically sistered to each of the existing joists, plus with cross-"joists" for additonal support.

We considered the "shim" idea, too, but we decided that it would be way too difficult to get the floor uniformly level all the way across if we did that-- plus, we had to come up with a solution for the wide space between the existing joists.

It took a while, but the floor is super-solid and is now probably the most level floor in the whole house.

your idea is basically the same as i did . used the shims and a four ffot level when thru and before putting down floor covering i used liquid leveler to even up -- just mix it up puor it out levels itself.. drill nail sand whatever ..

This is Jeff, the person who started the thread.

We measured the waviness of the floor and two opposite corners have a height difference of 8.5". The floor to ceiling height is more or less the same in the two parts of the room, so I think that leveling the floor will make the whole room look worse, rather than better. Right now the windows and doors look horizontal with respect to the floor, but if I were to relevel the floor there would be a huge angle between the bottom of the windows and the floor.

So I think that either the house settled at some point (a while ago), or it was just built unlevel. If anyone has any suggestions, I'd love to hear them.

Thanks again.

So the room is so far out of plumb/level/square, that fixing any one part of it just makes the defects of the rest glaringly obvious.

Sounds like the guys who saw it and suggested demolition and start over knew what they were talking about.

Best idea I have short of that solution is:

1. Level floor using your choice of methods suggested.

2. Reframe door and window openings level and plumb. [This is going to be one of those "Where does the demolition stop?" deals.]

3. Reinstall windows and door units, or new ones if necessary.

4. Install a (level) suspended ceiling.

I suspect that when you get estimates for this work, you will find they are not much less than the ones for the "demo and start over" approach.

After all this, it might wind up looking OK inside, but the exterior will still look funky. For this much work, I would probably just ante up however much more a complete rebuild would cost, and get a kitchen that looked decent inside and out.

All great suggestions with one flaw. You may NOT want the floor level (to the bubble). But, rather level to the room. It sounds like your upset with current condition is the inconsistent sag across the floor.

#1. Leveling the floor may leave you with little if any base board on one or more sides/corners of the room. Or depending on how you start project, you could end up needing +5" on top of the existing baseboard on one or more sides of the room.

#2. I believe the floor you are looking for is flat. One that you can place tile or some other substrate to and not get cracks or pull up. To accomplish this flat floor your co-workers and others ideas of taking up the floor will work although put away the level. Use a snap - string and measure from corner to opposite corner. Leave your string in place and tie off the other remaining corners. This will give you an idea of what your floor is doing and where shims/hewning may need to occur.

#3. Be very very cautious of anyone who wants to jack up your house. Unless the house is settling and continuing to do so at a pace faster than your going to live, my experience will advise that your looking for 20 - 40 year enjoyment. Who cares what happens after that and if you do build the house on pylons to insure the will be no settling ~ luck will have it that a tornado or some other unfortunate event will occur.

Remember ~ 'The enemy of good is better'. Get it good and enjoy!