Clogged gutters don’t flood basements here, because almost nobody has one. What they do instead is rot the fascia, get behind the stucco, pool water against the slab, wash out the landscaping under the eave, and turn the gutter into a rat and mosquito habitat. That damage is slower and quieter than a flooded basement, and it’s usually well underway before anyone notices.
Here’s where the water goes on a typical Southern California house when the gutter can’t carry it, one part of the house at a time.
What does overflow do to the fascia?
The fascia is the board the gutter hangs on. On most homes here it’s wood, painted, and it sits right behind the gutter’s back edge. When the gutter is full, water doesn’t only go over the front. It goes over the back too, between the gutter and the fascia, and runs down the face of the board.
Wood that gets wet every storm and dries in between starts to soften within a season or two. Paint peels, the board goes punky, and the gutter hangers lose their grip. Then the gutter sags, holds more water, and the cycle speeds up. On older homes in North Hollywood and Van Nuys we routinely find fascia you can push a screwdriver into. Replacing fascia means taking the gutter down, and by then the gutter’s often past saving too.
Water that gets past the fascia reaches the roof sheathing and the rafter tails. That’s structural, and it’s a roofer or a carpenter, not a gutter company.
What does it do to stucco?
Most houses in the Valley, the Santa Clarita Valley and the Conejo Valley are stucco over wood framing. Stucco is porous and it’s designed to shed water that hits it at an angle, not to have water running down it in a sheet for hours.
When an overflowing gutter dumps water down a wall, the water gets into hairline cracks, which every stucco wall has, and behind the stucco at the base where the weep screed is. Behind the stucco is building paper and then the wood framing. Wet framing behind stucco rots without anyone seeing it. From the outside you get dark staining, white efflorescence, and eventually stucco that sounds hollow when you tap it and comes off in sheets.
The corners under a downspout are the classic spot. A downspout that’s disconnected or clogged at the top dumps water down the corner of the house, and the stucco there fails first.
What does it do to a slab foundation?
Nearly every house built here since the 1950s sits on a concrete slab. No basement, no crawlspace. Water that overflows the gutter lands right at the edge of that slab.
The soils in much of the Valley and the surrounding hills are clay-heavy. Clay swells when it’s wet and shrinks when it’s dry, and a slab that’s wet on one edge and dry on the rest moves unevenly. That’s where slab cracks, stucco cracks at the corners of windows and doors, and doors that stick after a rainy winter come from. Water sitting at the slab edge also erodes the fill under it, and gets under it, which is the kind of problem that shows up as a damp spot on the floor in a room you didn’t expect.
Downspouts are supposed to carry the water away from the slab, out to a splash block, an extension, or an underground drain to the curb. When the gutter overflows, all of that is bypassed and the water goes straight down at the wall. Our downspout guide covers the drain side of this.
What does it do to landscaping and slopes?
Water coming off a roof edge in a sheet hits the ground hard. Under a chronic overflow you’ll find a trench worn into the mulch, plants beaten down, and soil splashed up the wall. Where the gutter overflows at a corner, the concentrated stream digs a hole.
On hillside lots it’s a bigger deal. Homes in Topanga Canyon, Sherman Oaks, Agoura Hills and the canyon neighborhoods around Canyon Country often have a slope right off the downhill side of the house. Roof water that should go into a downspout and a drain instead pours onto the slope, saturates it, and starts erosion. Over a few winters that’s a washed-out slope, a leaning retaining wall, or in a bad year something worse. Hillside drainage is a big part of why long downspout runs to the street exist in those neighborhoods, and it all depends on the gutter feeding the downspout.
What pests do clogged gutters attract?
Mosquitoes first. A gutter with standing water and decomposing leaves is a mosquito nursery, and our rainy season overlaps with the months when they’re active. If you’ve got a mosquito problem and you can’t find the source, look up.
Rats second. Roof rats use gutters and downspouts as highways to the roof, and a gutter packed with leaves is nesting material and shelter. They chew through the eave vents and into the attic from there. A downspout full of debris is also a rat ladder.
Then birds, which nest in gutters and downspouts and pack them with material. Termites and carpenter ants, which go after the softened fascia. And whatever seeds land in a wet gutter sprout, so we regularly pull out ferns, grass and small trees.
How does this show up in the house?
Peeling paint on the fascia or the underside of the eave. Dark streaks down the stucco below the gutter line. Tiger stripes on the gutter face itself, which means it’s been overflowing for a while. A musty smell in a room on the side of the house where the gutter overflows. Cracks in the stucco at window and door corners. Doors that stick in winter. Mosquitoes. Scratching in the attic.
Any of these is worth a look at the gutters first, because gutters are the cheapest thing on that list to fix. Signs your gutters need repair covers what to check.
What does it cost to prevent?
A gutter cleaning. Two of them a year for most homes, more if there are oaks or pines over the roof. How often to clean gutters has the schedule. Every one of the problems above starts with water going where the gutter should have carried it, and every one of them costs more than years of cleanings to repair.
The tiger stripes clean off with gutter brightening, which is the exterior streak removal we offer. The rest doesn’t clean off. It gets repaired or replaced.
The simplest way to make sure it doesn’t happen is the membership plan, which puts the cleanings on a schedule so nobody has to remember. It’s free to join and the more frequent plans cost less per visit. Or call (818) 913-1626 Monday through Saturday 7am to 7pm and get an estimate for a one-time cleaning.