I live in an 1885 greek revival in the D/FW area in Texas. (I say this because of the soils in the area). The upstairs is more unlevel than down stairs but does slope to the same direction. Two of the bedrooms, where the slope is the worst, have sagging floors. They are hard wood. The floors sag in to the middle in both rooms. Under the rooms are two living areas but show no sign of the sag from down stairs. Has any one heard of this?
If I understand what your talking a out Sometimes in old houses false ceilings are put in to make things look good. At one time there could have been a bearing wall under the bedrooms that was removed by someone who didn't understand those things. After the floors sag and it shows downstairs they come in and put a false 2x4 ceiling in level and drywall it. The only way to tell for sure is to open up the ceiling. But you may get an idea by pushing a wire through the ceiling and see how far up it goes. If its in the neighborhood of 10-12 inches then you probably have a false ceiling. generally old houses have native 2x6 or 2x8 ceiling/floor joist.
I have the same problem of sagging 2nd story floors in my 1904 foursquare. Question is, how to best go about fixing the problem? Fixing first floor sags are no problem: just add jacks/support in the crawlspace. But how about on the second floor when the sag is over an open room below?
Without the original floor plan its hard to tell if a bearing wall was taken out. Rooms were smaller in the old days. That being said if it doesn't go against historic rules of preservation modern micro lams can be installed that may alleviate the problem. but not knowing all the facts it can also be considered conjecture on my part.
I had the same issue at my casa in Texas....to correct the problem i first had the main beams all leveled up for the foundation of the house....no need doing anything until that is taken care of....i would bet the problem is as stated - you may have 2x6 joist, which over the years have given in due to not enough support. I have seen a ton of old houses with this same delima.....i imagine as posted they corrected the prob cosmetically on the ceiling of the 1st floor.....or.....it not as noticible....have you gotten on a ladder and eye balled the ceiling? If not, you may find it's sagging down.
To correct the prob as posted already - you can use laminate beams, but I did not want that large of a beam drop. I had 3/8" steal solid run plates cut 8" wide (machine cut not heat cut or they will warp). I had holes 1/2" punched staggered and bolted 2x10's on either side. Essentially, made a laminate beam using steel. Much stronger and gives you the shallow beam. We bolted them all together - jacked the ceiling and installed them. I did not want to rely on the weight being carried by the load bearing walls since the houses in that era were "balloon construction".....while the house overall is very strong you will find the stud placements are pretty wide. This is because a lot of the strength comes from teh horizontal supports in the walls and the boarding added horizontally. In short - i did not like the idea of the concentrated weight a beam will create.
What we did was went into the walls where the beams would rest and inserted studs - sandwhiched solid from the base of the beam - down the wall - thru the floor and to the main beams under the house. I was lucky and all the ones I added were either right over pier supports or within inches. That places the weight of the support right where you want it to be.
Doing this allows you a beam that is only 9 1/4" thick instead of the much wider one needed by the laminate. The beams were then encased to match the wide wood casings of the wndows/doors and baseboards. Actually, the beams turned out to look great and I had them trimmed with crown along with the rest of the rooms. This gave a picture frame affect to the ceiling. 2 beams added in the two rooms of concern, which created 3 picture frame areas if you can imagine what I am saying. We painted the beams and crown all an white (little cream tint) and painted the ceiling a shade lighter than the walls. It made the beams and crown really pop and become a focal point.
I will post some pics so you can see what I am talking about. Floors/ceiling straight and strong - you still and always will have some vibration from upstairs romping around, but no more trampoline action.
OH - if you decide to do this let me know and I will diagram it out....also, make sure with any beam (as i described or laminate) that you king-stud the outside in the wall and block them....this will prevent them from twisting - you will not have to worry about bending or sagging.