First of all you didn't mention if you are removing the existing kitchen cabinets and replacing them? If you are, I would level the area that will be under your new kitchen base cabinets only. This will insure your new kitchen cabinets are nice and level. Build bases and a plywood platform that is level for the new base cabinets. If you are not replacing the cabinets, I don't know if I would go to the trouble of leveling the floor, and if i did I definetly would not use a self leveling compound, of any kind. That old subfloor is going to move still, and eventually that self leveling compound is going to flex,crack,and disintegrate. Remember some things will be affected by an inch increase in the floor level. If you have a dishwasher and you level the floor you may not be able to get dishwasher up and out from its position should it need replaced. And if you pull it out to put new floor down - you may not have enough room to slide it back in and fit under the counter top. Your refrig will be up higher also - What about doors? If you have an inswing exterior door it may hit your raised floor? If you insist on leveling the floor- I would hire a good carpenter and do the job by scribing wood pcs. to fit contours of old floor placing them on 12 centers screwed and glued down into the old floor. * tighten up any loose areas on old floor first* Allow enough room on scribed pcs. to install at least 1/2 thick underlayment, and your finished flooring. Remember - old houses can't be expected to be new - some of the characteristics of an old house are- squeaky uneven floors,walls,ceilings.
You already have some answers on repairing the problem. I won't try to add to those. My old family home was built in 1850 and there is hardly a room in the house that has a level floor. You can drop a marble in most and it will roll off to the side of the room. One room, now enclosed, was once the floor of an open back porch and the floor slopes about 2 inches from one side to the other. However, the house has only provided shelter for 5 generations of my family so far, but I think I will let my great-grandchildren worry about it. Good luck.
Instead of using concrete because you would be adding more weight to your floor and your floor might not be able to handle the weight. You could put in a false floor. Depending on the pitch. You would be ripping 2x4 (or which ever size that you would use) on the angle that your floor pitches. These would be like the floor joist below. Then lay some new plywood on top. This way you wouldn't have as much weight added to your floor. If you still want to use a more denser product you could add support to your floor from the basement or crawl space below. Good luck
old houses with continue to keep settling using a concrete type self leveling is good but if keeps moving it will crack it and cause more problems with new floor. try using the thinest plywood (1/4 inch) on the low side keep adding until somewhat level. sreww every squared 6 inches. its what they do before laying tile, on old houses
Isn't there an advantage to having a leaning floor? at least if you spill something it will tend to go in one direction and is easier to clean up.? Just a thought.