Sagging ceiling could be an indication of framing issues some of which could be related to the roof.
Roof sagging near chimney.
To determine what is causing your chimney to lean take a look at the angle.
Keep your attic well insulated and ventilated to prevent ice dams which can cause roof leaks.
A chimney that is leaning away from a house or appears to be falling onto a yard indicates foundation issues.
Weight related sagging can also be caused by design flaws that leave the roof unable to support its own weight.
The beam is attached to both exterior walls and to the.
Sagging rafters may be the result of having framed the roof with lumber of dimensions smaller than current building standards such as using 2x4s or 2x6 s or there may be damage to the framing from insects or rot.
Common flaws include undersized rafters insufficient sheathing or too few rafter or collar ties.
Because where the chimney comes through there is going to be some framing that takes the flooring around that and that s probably the reason that the floor is sinking in the area of the chimney and walls that are resting on that floor would move accordingly.
Should the bottom cord of one or more trusses be sagging or damaged it may be reflected in a sagging ceiling or if the roof is over loaded to heavy then the downward pressure may cause the sagging.
A chimney that appears to be falling onto a house or roof indicates that serious structural problems exist.
Also inspect the metal or plywood gusset plates used where your wood meets on a truss look for damage that includes cracks rot breaks and any other impairment.
Fixing a truss or rafter.
Causes of chimney failure.