You will need to remove the shingles and the old decking however which means there will be an exposed hole in the roof.
Repairing a sagging dip in roof.
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.
You may find that.
You can simply have the old sheathing replaced with better material when it s time for new roofing.
Check the ceiling for sagging by attaching a string on one end of the beam and run it along the bottom edge of the beam.
Often the framing can be bolstered and beefed up internally but if the roofing material needs replacement anyway it may be best to tear off.
The first step is to find out how many rafters are sagging and if anything else is damaged.
Remedies for a sagging roof there are a number of remedies for traditional rafter style roof frames depending on the problem and its severity.
This may be problematic in winter months but allowing the roof to continue to sag can lead to greater problems such as a cave in.
How to straighten sagging roof rafters.
If a roof dips in between rafters or trusses it s probably because the sheathing is too thin for the span.
If the sagging roof is due to rotting or warping roof decking the repair will be much easier.
Drill holes in angle iron.
Stabilizing a sagging roof with trusses joists.
Bolstering the beams of your roof is another solution to repairing a sagging roof however it is often something that requires assistance from another able bodied person since beams can be extremely heavy.
Sagging ceiling could be an indication of framing issues some of which could be related to the roof.
Fixing a sagging roof by bolstering the beams.
When i bought my house the garage roof had a sag.
Weakened sheathing rotting joists and sagging insulation are some possible causes.
Determine the extent of damage.
To correct the sagging itself angled braces can be installed to shore up the rafters.
That might mean replacing the shingles and flashing repairing your gutters and improving the attic ventilation.
If structural damage or decomposition is to blame it may be best to tear out the section of roofing and repair the problem before filling the hole.
If water damage is causing your roof to sag your first step will be to correct the problems that allowed the damage to occur.