Gutter overflowing at one corner
One corner spilling while the rest of the gutter behaves is almost never a sign that the whole system is too small. Water from two or three roof planes usually meets at that corner, and either it cannot get out fast enough or the run has dropped so the low point is no longer at the downspout. Find which, then fix that one thing.
The symptom
What you are seeing
- In steady rain the gutter looks fine along most of the house. At one corner, usually below a valley where two roof slopes meet, a sheet of water pours over the front edge and lands on the path or the planting below. After the rain there is a scoured patch in the soil, a tide mark on the siding or a green streak down the wall where the same spot keeps getting wet.
- From the ground, look at what feeds that corner. Count the roof planes draining toward it and whether a valley aims straight at it. Look for a downspout at or near the corner, and check whether the gutter looks level or dips away from it. If you can see a dark line of debris along the back edge, or a downspout that never seems to run even in a downpour, note that too. Those are the observations that shorten an inspection.
Most likely first
Likely causes
A blocked outlet
The opening into the downspout is the smallest hole in the whole system, and it is where leaves, roofing grit and the odd tennis ball end up. When it is choked, water backs up along the run and finds the lowest edge, which is often right there at the corner.
Valley runoff arriving too fast
A valley concentrates rain from two slopes into a narrow stream that hits the gutter at speed. In a hard burst it can shoot straight over the front lip, or land so much water in one short stretch that the outlet cannot keep up even when it is clear.
The run has lost its fall
Gutters are hung with a slight slope toward the downspout. When hangers loosen or the fascia behind them softens, a section sags. The low point moves, water settles where there is no way out and the corner becomes a pool that spills.
One small downspout doing too much
A single narrow downspout can be asked to drain more roof than it should. The gutter may be big enough, but the way out is not. Adding an outlet, moving one or fitting a larger downspout changes that without touching the rest of the run.
The honest rule
Repair or replace
This is nearly always a repair. Clearing the outlet, resetting the fall with new hangers, adding a second downspout or fitting a splash guard on the valley side of the corner are each a few hours of work, and one of them is usually the answer. What we look for first is whether the metal itself is sound: a corner that has been wet for years can rust through at the seam, and a joint that has been resealed several times is telling you something about movement.
Replacement comes into it when the sag is caused by fascia that will no longer hold a screw, when the corner seam has failed beyond resealing or when the same house has three or four corners behaving the same way, which usually means the original layout never had enough outlets. Even then the fix is a new run with better drainage, not bigger gutters everywhere. If someone quotes a full replacement for one spilling corner without explaining why the corner spills, ask them to.
What fixes it
The service for this, and where to read more
Service
Gutter repair
Repairs for leaking joints, loose supports and sagging runs when the rest of the gutter can stay.
Service
Gutter cleaning
We remove debris, flush the channels, clear the downspouts and report the condition we find.
Guide
Repair the gutters or replace them
A repair can make sense when a joint, support or short section has failed and the rest of the gutter is sound.
Related problem
Gutters overflow in heavy rain
If the gutters drain a light rain and spill along their whole length in a hard one, the run is being asked to move more water than its outlets can pass.
Related problem
Water pooling next to the foundation
Water standing against the foundation after rain is a drainage problem that often starts at the roof.
Questions
Asked about this problem
Can I fix an overflowing corner myself?
If the cause is a blocked outlet and you can reach it safely from a ladder, clearing it is reasonable. Resetting the slope of a run or adding a downspout means unhanging metal and refastening it into sound wood, and getting the fall wrong just moves the pool somewhere else. Have that part inspected first.
Would a splash guard stop the water shooting over the corner?
Often, yes, when the valley is aiming a fast stream at the front lip. A splash guard is a short raised plate on the outer edge that turns that stream back into the gutter. It does nothing for a blocked outlet or a sagging run, so it is fitted after those have been ruled out, not instead of checking them.
Does one overflowing corner mean my gutters are too small?
Rarely. If the rest of the run drains, the size is doing its job. The corner is a drainage problem, meaning what arrives there and how it gets out, and that is solved with outlets, slope and clearing rather than with a wider channel. A wider channel on a run that still cannot drain will simply hold a bigger pool.
Free estimate
Find out what it costs
Tell us what's happening at your property, one step at a time. We'll review your request during business hours and arrange a free inspection.
What happens after you send it
- We call during business hours to set a time.
- A free visit. We measure on site and nothing is signed at the door.
- The proposed work and the price, in writing.
- (925) 555-0100Phone
- Mon–Fri 7:00 AM – 5:00 PMHours
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100 Example Road, Brentwood, CA 94513 · office@example-roofing.demo
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