Detailed Answer
Gutter sagging is a structural failure, not just a cosmetic issue. A sagging gutter holds standing water, accelerates corrosion, creates a heavy debris accumulation point, and eventually pulls away from the fascia — taking wood with it.
The most common cause in Sacramento is debris-weight stress on inadequate hanger spacing. Gutters should be hung on hangers spaced 24 inches apart or less. Many older Sacramento homes were originally installed with hangers 36–48 inches apart — adequate for light debris but not for a gutter full of wet oak leaves and acorns. Over time, the constant weight of debris and standing water bends the gutter profile at hanger midpoints, creating a visible bow.
Hanger spike failure is the second most common cause. Older gutters were often hung with long aluminum spikes driven through the gutter face into the fascia and rafter ends. These spikes loosen over years of thermal expansion and contraction, eventually pulling out far enough that the gutter is resting on the spike rather than being held by it. The fix is replacing spikes with hidden hanger screws — a much more secure connection point.
Fascia rot is the most serious underlying cause. If the fascia board has been absorbing moisture from a leaking gutter joint or overflow contact, the wood softens and no longer provides a firm anchor for hangers. You can re-drive fasteners repeatedly, but they won't hold in deteriorated wood. Correct repair requires replacing the damaged fascia section before rehanging the gutter.
Ice and snow loading, while uncommon in Sacramento's valley floor, can cause sagging on foothill properties in Auburn, Placerville, and El Dorado Hills that experience periodic ice storms or heavy snow. The weight of ice in a gutter is far beyond what the hanger spacing was designed to bear.