Undersized rafters also can cause sagging along the whole side or plane of a roof.
Roof bowing in the middle.
One of the most common causes of roof issues are problems related to the rafters or trusses.
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.
They have issues for a wide variety of reason including damage from wind storms overloading from ice and snow leaks etc.
Therefore giving them a good look is critical when addressing sagging bowed or wavy roofs.
There are different reasons and types of curling.
What causes a sagging roof line.
It might be something.
If you can see a dip curve or swag on the peak when standing in the street your roof has a problem.
That s why most of the ridge sagging occurs in the center of the roof page top photo.
Roof lines should be arrow straight.
In a stick frame non truss sloped roof these issues usually cause the roof ridge to sag in the middle giving it a swayback look but can also cause one side of the roof to sag.
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.
Installing new rafters directly alongside the weak or damaged ones is often enough to correct this problem.
A ridge that droops in the middle forming that unintentional western design feature likely is due to undersized rafters and or missing or inadequate internal bracing rafter or collar ties.
This often occurs in the middle of the shingle tab.
If your rafters are still sagging a bit and it is causing your roof to dish out a little in the center of the roof sides add a 2x4 that goes all the way across the rafters in the center of the length of the rafters.
Repairing a roof rafter in this condition is not a hard project but it can be difficult if there is not easy access.
Curling shingles also referred to as fishmouthing is when asphalt shingles have curled on the ends and appear to be bent or twisted.