What is a gutter valley splash guard, and do you need one?
Why valleys overshoot
A valley is where two roof slopes meet, so it collects water from both and delivers it in one fast, concentrated stream. On a steep roof in a hard Georgia thunderstorm, that stream can leave the roof with enough speed to clear the gutter's front lip entirely. The giveaway is a trench in the mulch, mud splashed on the siding, or water pouring over one corner while the rest of the gutter handles the rain.
How a splash guard fixes it
The guard is a short L-shaped or angled piece, usually aluminum in a color to match the gutter, that rises above the front lip at the corner. It is screwed or riveted to the gutter and sealed. Water that would have overshot strikes it and falls into the gutter. It is inexpensive and does not touch the roof.
Other fixes to consider
- Bigger gutter or more outlet. If the corner overflows rather than overshoots, the gutter or downspout is undersized. A 6-inch gutter or a downspout near the corner helps.
- Check the valley itself. The valley metal or shingles should end over the gutter, not short of it, or water can run behind the gutter.
- Watch your guards. Some guard styles make overshoot worse at valleys and need trimming or a splash guard there.
Avoid diverters that require lifting or nailing through shingles in the valley, which can create the leak you were trying to prevent. More on valley and edge details in roof flashing explained and gutter sizing, seamless gutters and guards.