If these already exist nail a 2x4 to them directly under the 2x4 plate you nailed down before.
Sag in my roof.
Why roofs sag as mentioned roofs sag because there s too much weight or load for the existing structure.
If you notice that there is a visible dip in your roof chances are you have a problem with one or several rafters and you may soon be facing more issues like water leaks bowed out walls or your roof caving in on you.
Once you have established how much the roof sag needs to be jacked up lay a 2x4 plate across the ceiling joists and nail directly under the ridge of the roof.
Rotten or saturated sheathing can also cause roof lines to sag.
A sagging roof is not only an eyesore but it could also be dangerous for you and your family.
Two or more roofs on one structure spell trouble.
If you have just stepped outside your house and realized that your roof is no longer straight this could signal a problem.
Non foundational reasons for a sagging roof.
Every roof is designed to support a specific maximum weight and anything above this especially for long periods can cause the roof to sag.
This is the easiest problem to repair.
If the framing is.
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.
The home may not be designed to support the weight of this extra roofing material and it will sag.
Additionally if your roofer has used material that is much heavier than your previous roof it can sag for the same reason.
Fixing a sagging roof as soon as you spot it is very important otherwise you could find that the problem will only worsen over time and in the end you may need to have the entire roof replaced which could be extremely costly not to mention a lot of hassle.
Sagging rafters can lead to serious problems with the entire roofing system.
Now add collar ties from one side of the rafter to the other.
Since roofs are designed to be straight a curved or sagging roof means that its structural integrity is insufficient and it may be a warning sign that your roof is headed for collapse.
If the sagging roof is due to rotting or warping roof decking the repair will be much easier.
You will need to remove the shingles and the old decking however which means there will be an exposed hole in the roof.