Gutters overflowing but not clogged? Here's what's really happening
A clean gutter that still overflows the front edge in hard rain is not clogged. It is one of three things: the gutter has lost its pitch toward the downspout, the downspout is too small or partly blocked, or there is no drip edge so water sneaks behind the gutter. You fix the cause. The only thing I bought was a tube of sealant.
- Extension ladder on a board if the ground is soft
- A level to check the gutter pitch
- Caulk gun if your sealant is a cartridge
We got one of those August storms that shows up angry and leaves in twenty minutes. I stood at the kitchen window and watched a sheet of water pour over the front of the gutter above the back corner of the house, straight down the brick, into the exact patch of yard that already holds water for two days after every rain. The back-left corner. Write that down, because you and I are going to spend a lot of time there.
The gutters are clean. I know they are clean because I am the fool who cleans them. So if it is not a clog, what is it.
The three real causes
- Pitch. A gutter is supposed to tilt, just barely, toward the downspout so water runs to the drain instead of pooling and spilling over the front. Twenty-five years of hanging full of water and ice pulls a section flat or backward. Mine had sagged in the middle of the run so the water had nowhere to go but over the lip.
- Downspout. If the downspout is undersized or half-blocked where it meets the gutter, water backs up and overflows even with a clean trough. Check that the opening into the downspout is clear.
- Drip edge. This is the sneaky one. If there is no drip-edge flashing tucked behind the gutter, water clinging to the shingle edge curls back behind the gutter and runs down the fascia. From the ground it looks like the gutter is overflowing. It is not. It is being bypassed.
What I did
I put the ladder up, waited for the rain to quit, and checked the pitch with a level along the run. The middle hanger had let go and the section had gone flat. I re-seated the hanger to bring the pitch back toward the downspout, and I ran a bead of gutter sealant along a seam that had started weeping while I was up there. Water tested clean off the next storm. The corner still floods. That is not the gutter's fault, and it is a bigger story, and I am not ready to tell it yet.
What went wrong
I set the extension ladder on soft ground, in the corner that holds water, because I do not learn. The foot sank, the ladder lurched, and I said something that cost the jar fifty cents and gave Gary something to laugh about over the fence. Put the ladder on a board. And do not get on a wet roof or lean out past your belt buckle for a gutter. There is no gutter repair worth a fall.
When it's bigger than the gutter
If the gutter is pitched right, the downspout is clear, the drip edge is there, and water still comes over in heavy rain, your gutters may simply be undersized for your roof, or the downspout is dumping right against the foundation. That is where the water in my back-left corner comes from, and fixing that is not a tube of sealant. Hold that thought. We will get to the corner.
The Damage
| Item | Where | Cost |
|---|---|---|
| Amerimax SeamerMate 10 oz gutter sealant (85148) | Home Depot | $9.98 |
| Sales tax | $0.60 | |
| Total | $10.58 |
Deb's verdict. "You went up a ladder in the rain to look at a puddle you already knew about."