Staining on the siding below the gutter

This is usually overflow at a specific point. Trace it. The fix is a clog or a pitch issue at one section, not the whole run.

Quick answerStreaks or dark stains on the siding under a gutter mean water is going over the front, through a seam, or behind the gutter at that spot. Most of the time it’s one section: a clog near an outlet, a sag that holds water, or a leaking joint. Find the exact spot in the next rain, fix that section, then clean the siding. You can handle this one yourself. No call needed.

The stain is a map. Its shape tells you how water is escaping, and its position tells you which part of the gutter to fix.

1Read the stain

Stain pattern	What it usually means	Where to look
Wide streaks from the top edge	Overflow over the front lip	A clog or sag at that section
A narrow drip line	A leaking seam or end cap	The joint directly above
Stains starting behind the gutter	Water running down the fascia	A missing drip edge, or a gutter pulled off the board
Splash marks near the ground	Water hitting hard ground and bouncing	The downspout outlet and its discharge

2Trace it

Watch in the rainStand back from the house during a steady rain and find where the water leaves the gutter.
Or use a hoseOn a dry day, run a hose into the gutter upstream of the stain and watch from a safe ladder.
Check the sectionLook for leaves packed near the outlet, a dip in the run, or old sealant at a seam.
Check behindIf water is coming from behind the gutter, look for a gap at the fascia and a drip edge at the roof edge.

3Fixing it

Do it yourself

Clear the clog and flush the downspout
Re-hang a sagging section so it falls toward the outlet
Clean, dry and reseal a leaking seam with gutter sealant
Wash the siding gently once the leak is fixed

Get help

Water is running behind the gutter and the fascia is soft
The section is on a second storey
Many seams leak along the run

Fix the leak before cleaning the siding, or the stain comes back. Use a soft brush and a mild cleaner. High-pressure washing can force water behind siding.

Ladder safety

Don’t lean a ladder on the gutter, and don’t work at the roof edge alone. Read cleaning from a ladder alone first.

4What drives the cost

Most stain sources are a clog, a sag or a seam, and those cost little to fix. Cost rises if the fascia behind the gutter has rotted, if a drip edge has to be added, or if the whole run is too small and overflows everywhere.

Gutters cost

5Questions

The stain is along the whole wall. Is that still one section?

Probably not. Overflow along the whole run is a capacity problem. See water spilling over the front edge in heavy rain.

Does the staining mean the siding is damaged?

Usually not at first. Long-term wetting can damage wood siding and trim, so fix the source and check for soft spots.

Should I replace leaky sectional gutters with seamless?

Reseal a few leaking joints. Consider seamless only when many joints keep failing.

Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.