A sagging roof is the result of inadequate structural support for the weight of the roof. Most commonly you’ll notice this in the ridge of the roof, often the middle will sag while the ends remain upright, creating a saddle shape. You may also notice sagging in the soffits, overhangs or rafters.
Don't ignore your sagging roof
A sagging roof rarely manifests on its own. If your roof is curved it’s likely the result of old age, structural damage from years of storms, heavy snow, or poor construction. Letting the problem persist will only allow those factors to continue eroding away at the integrity of your roof until your roof suffers a catastrophic failure