The first step is to find out how many rafters are sagging and if anything else is damaged.
My roof is sagging.
Deflection is the immediate sag produced when an object is set on a structural member.
If your home has converted from shingles to tile you may need to add structural bracing in your attic to hold the extra weight.
Too many layers of shingles this is why we never recommend adding new shingles over old ones improper design.
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.
Another reason your roof may be sagging is because it can t handle the weight of the roofing material.
Step 1 the first step is to the basement first.
Here are some of the most common ones.
Straighten out your old house s sagging roof and get rid of those cracks in the wall with these easy to follow steps.
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.
You may find that several are in need of straightening and that some of the sheathing must be replaced.
Ice or snow buildup.
A bunch of different issues can potentially be at the root of your sagging roof problems.
If your roof is sagging under the weight of too many shingles ideally all the shingles should be removed and a new set installed.
When the roof framing is assembled two ceiling rafters are often joined together to create a longer span.
That s why most of the ridge sagging occurs in the center of the roof page top photo.
This gives your roofer a chance to inspect the flashing and roof underlayment for damage.
Grab a flashlight and head up to your attic to inspect your roof rafters and decking specifically those where your roof is sagging.
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.
For example tile roofing weighs way more than your typical asphalt shingle roofing.
Why roofs sag as mentioned roofs sag because there s too much weight or load for the existing structure.
Fixing a truss or rafter.
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.
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.
