That s why most of the ridge sagging occurs in the center of the roof page top photo.
My roof is sagging.
You may find that several are in need of straightening and that some of the sheathing must be replaced.
Grab a flashlight and head up to your attic to inspect your roof rafters and decking specifically those where your roof is sagging.
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.
As the wall tops are pushed outwards at their center either the entire wall leans over or as the wall is held up at the building corners gable ends the wall center may break and bend over as in my photo above.
When the roof framing is assembled two ceiling rafters are often joined together to create a longer span.
However it is important to fix the rafters before doing any other work to the roof.
Sagging or low spots in a flat roof may be due to undersized or weakened roof joists or problems with the buildup layers beneath the exposed roofing.
Another reason your roof may be sagging is because it can t handle the weight of the roofing material.
Straighten out your old house s sagging roof and get rid of those cracks in the wall with these easy to follow steps.
If your roof is sagging under the weight of too many shingles ideally all the shingles should be removed and a new set installed.
Too many layers of shingles this is why we never recommend adding new shingles over old ones improper design.
The first step is to find out how many rafters are sagging and if anything else is damaged.
Sagging roof lines can originate with the horizontal ceiling rafters.
Why roofs sag as mentioned roofs sag because there s too much weight or load for the existing structure.
If the sagging appears in the plane of the roof that is up and down between the ridge and the eave and from side to side the sagging is probably due to deflection and creep of the rafters themselves figures 8 and 9.
A bunch of different issues can potentially be at the root of your sagging roof problems.
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.
Step 1 the first step is to the basement first.
Why is my roof sagging.
This gives your roofer a chance to inspect the flashing and roof underlayment for damage.
If your home has converted from shingles to tile you may need to add structural bracing in your attic to hold the extra weight.
Fixing a truss or rafter.
Deflection is the immediate sag produced when an object is set on a structural member.