How to fix a sagging floor?
When I read bedroom upstairs, that tells me both the floor and the ceiling below are finished surface, so what ever has to be done is going to be messy, time consuming and $$$. If the defection increases with live load, tells me the joists are not adequate, additional layer of sub floor may help, but it would be my opinion it Will do more harm than good (hopefully this room is far larger than the rest of the upstairs rooms). To sister these joists, you will have to remove the ceiling below, and gain access to the top plates to the bearing walls. Chances are, there will be wires, plumbing, etc in then way so you have to deal with them. Further complications arise when you consider the center of the floor is now lower than outer edges so that has to be leveled one joist at a time and the sisters have to extend well back onto the top plates to do any good. Once you get the sisters in place they should be glued and screwed into place (including a bead of glue on the top to grab the sub floor and not squeak in the future) This is not a small job, good luck!
In a really old house ' its called charm In general there is nothing charming about a dip that bad which gets worse w/ some weight on it. Could be a load bearing partition was removed during a remodel ?. Being upstairs complicates things , but a good carpenter should be able to sort it out. If the ceiling below also dips because of the sagging joists Supporting & sistering on some straighteners might fix 2 problems & save work over the long run. Would be a little leery of just adding adding subflooring to disperse the weight also. Got to find the cause before you come up w/ a cure. If the home inspector is the engineer hired by mom as part of the presale inspection & has noted the problem he should also be able to recommend a fix ( other than more flooring) & maybe for a few more bucks) that the owners would take on as a condition of sale. If it is a take it as is deal the engineers recommendation is good leverage to reduce the price enough to have a proper fix done after the sale. Engineers are hired to point out deficiencies that the buyer must consider when purchasing a house & not make recommendations on whether or not to buy. Although, a knowing wink is sometimes made if the house is a real stinker. Best regards
How To Fix Sagging Floors
a hundred YEARS previous is quite like US, WE SAG as a results of fact the YEARS flow by making use of. ARE THERE WEIGHT BEARING WALL in the path of the 2d floor? by the years the load contract is sparkling. IF NO TO THE ABOVE question there is two way. a million/ U CAN JACK UP THE CEILING on the 1st floor AND BRACE, this might TAKE the rigidity OFF the top floor JOISTING. make confident U HAVE sufficient BRACING on the 1st floor OR U WILL SAG the 1st floor DOWN. enable THE JACKED UP BRACING TO SET FOR consistent with week. 2/ flow to the 2d floor eliminate flooring AND NAIL extra floor JOISTS TO the prevailing ONE making use of a few wood worker GLUE AND NAIL THEM at the same time. USE LAGS SCREWS long sufficient TO PENETRAT the two JOIST. enable IT SET for twenty-four HOURS SO THE GLUE WILL DRY. THEN replace THE flooring and eliminate decrease BRACING. yet differently IS to eliminate THE CEILING SHEET ROCK AND JACK UP AS defined before AND USE a million/4 PLATE steel AND LAG SCREW INTO the prevailing JOIST..
Yes sistering would help, but only if you can get to BOTH berring points with the sisters. as far as the sub floor goes this would only HELP, if you do this support the ceiling below with a dead man, you may even jack it up a LITTLE, then glue and Screw the sub floor down. how ever if someone has removed a berring wall downstairs thats a whole other game !! hope that helps