Why do my gutters overflow? 5 causes

Gutters overflow for one of five reasons: they are clogged, the downspouts are clogged or too few, the gutter has lost its slope, the gutter is too small for the roof above it, or water is running behind it at the roof edge. Watch the gutter in a heavy rain and where the water spills tells you which.

1. Leaves and needles in the gutter

Under Portland's firs, maples and oaks, a gutter can fill in one fall. Water sheets over the front edge along the whole run. The fix is cleaning, and sometimes a guard.

2. A clogged or overloaded downspout

If the gutter overflows near one corner while the downspout trickles, the downspout or its elbow is blocked. If it overflows in a long run with only one downspout, there are too few. Adding a downspout often costs less than a bigger gutter.

3. The gutter has lost its slope

Gutters should fall gently toward each downspout. Hangers loosen, fascia sags, and water pools in the middle and spills there. You can see it from the ground after rain: standing water in a gutter that should be empty.

4. The gutter is too small for the roof

A long, steep roof sends a lot of water to one gutter in a downpour. Water shoots over the gutter at valleys and inside corners even when it is clean. Our guide on what size gutters a Portland house needs explains how sizing works.

5. Water is running behind the gutter

If you see drips or stains behind the gutter rather than over it, water is getting between the gutter and the fascia. This usually means a missing or short drip edge at the roof, or a gutter hung too low. Left alone, it rots the fascia board. Our Dry Rot site covers that repair, and our Siding & Roofing site covers the drip edge.

Why it matters

Overflow lands at the foundation, splashes the siding, and soaks the fascia. Most of the rot we are called for on fascia and siding sits right below a gutter that has been spilling for years.

What to do

Clean it once and watch it in the next big rain. If it still spills, the cause is slope, size, downspouts or the roof edge, and that is a repair or a replacement, not more cleaning. Where the water goes after the downspout matters too.

Our work is covered by a 2-year workmanship warranty, in writing.

Get a free gutter estimate or call Tim, (503) 597-8520.