How to Find a Gutter Leak Before You Call Anyone
"The gutter is leaking" covers four different problems, and they have four different fixes. Twenty minutes with a hose on a dry September afternoon will tell you which one you have, and it will make the call to a contractor much shorter.
You need a hose, a ladder tall enough to reach the gutter (or a helper on the ground while you run water from the roof edge), and dry weather. The last one matters. In the rain everything is wet and you cannot tell where water is coming from.
Step 1: Look before you run water
Walk the house and look at the fascia — the board the gutter is hung on. Dark streaks, peeling paint, a green tint of algae, or a soft spot under a screwdriver all mark where water has been getting past the gutter for a while. Note those spots. Then look at the ground: a trench in the bark dust, moss on the concrete, splash marks up the siding. Those mark where water has been landing.
Step 2: The corner test
Put the hose in the gutter a few feet from a corner and let it run gently. Watch the corner from below. A drip from the bottom of the mitre within a minute or two is a failed seal. Every corner on a Portland gutter eventually does this; the sealant never gets the dry week it needs to cure properly and lets go after 8 to 12 years. Do the same at each end cap.
The fix: clean the joint back to bare metal, dry it, and reseal with a polyurethane or tripolymer gutter sealant. $150–$260 per corner. This is the most common gutter leak repair Portland contractors get called for, and it is usually a same-visit job.
Step 3: The pitch test
Run the hose at the far end of a run from the downspout and let it fill. Watch where the water goes. It should move steadily toward the outlet and exit the bottom of the downspout within a minute. If it pools in the middle and the middle overflows before the outlet gets much, the run has sagged. Look for a green moss stripe along the low point — it is the tell.
The fix: re-hang the run on hidden screw hangers and reset the pitch, $150–$320.
Step 4: The outlet test
Move the hose next to the outlet. Turn it up. If water backs up around the outlet and spills over the corner while the downspout only trickles, the outlet is undersized (many are 2 inches) or the downspout is packed. Pull the bottom elbow off and look up.
The fix: clear the downspout ($60–$120 as part of a cleaning), or cut a larger outlet and drop to a 3x4 downspout, $180–$320.
Step 5: The behind-the-gutter test
This one fools people. Run water gently along the shingle edge above the gutter, not in it. Watch the fascia. If water appears on the fascia behind the gutter and drips off the bottom, the roof has no drip edge or the shingles stop short of the gutter. Common on cedar shake and on older composition roofs. It is not a gutter leak at all, but it rots fascia faster than any leak.
The fix: a drip edge flashing under the first course, $6–$12 a foot, or on shake roofs re-hanging the gutter tighter to the roof line.
Step 6: The seam test
If the gutter has joints every 10 feet, run water across each. A weep at the seam is a sectional gutter at the end of its life. One seam can be resealed; if three are weeping, read the repair-versus-replacement post.
What the results mean
| Where the water shows up | What it is | Typical Portland price |
|---|---|---|
| Drip from the corner or end cap | Failed seal | $150 – $260 |
| Overflow mid-run, moss stripe | Lost pitch | $150 – $320 |
| Backs up at the outlet | Small outlet or packed downspout | $60 – $320 |
| Wet fascia behind the gutter | No drip edge | $6 – $12 / ft |
| Weeping seams every 10 ft | Sectional at end of life | Replace |
What to tell the contractor
"The northeast corner drips within a minute of running water. The back run pools in the middle. The fascia behind the front outlet is soft." That is a call a contractor can often price over the phone within a range, and it turns a two-visit job into one. Bring your notes and photos when you request a repair estimate.
When not to bother
If the gutters are galvanized steel with a rust line along the bottom, skip the hose. Every test will fail and the answer is a new system. And if you cannot reach the gutter safely — two stories, a steep lot, wet moss on the roof — stay off the ladder. A professional cleaning visit should include every test above from the ladder, and it costs less than an emergency room.
Ladder safety before you start
The tests above are simple, but they all happen at the roof edge. A few rules keep them that way:
- Use a ladder rated for your weight plus tools, set on firm, level ground.
- Keep the top of the ladder off the gutter itself. A standoff arm rests on the roof or wall instead.
- Keep three points of contact, and do not lean out past the rails.
- Have someone on the ground to steady the ladder and watch the water.
- Skip it entirely on two-story walls, on steep slopes and in wind.
Leaks that only show in real rain
A hose puts water in one spot at a time. Real rain hits the whole roof, and a few problems only show up then:
Valley overshoot. Water from a roof valley can rush past the gutter at one corner. Watch that spot in a heavy shower.
Overflow from a full downspout. A downspout that takes water from two runs can back up only when both are flowing.
Leaks at the house wall. A gutter end cap tight against siding can drip down the wall behind it in steady rain.
Water from above. A leak in the roof flashing can drip onto the gutter and look like a gutter leak.
If the hose test passed and you still see water, walk the house in a steady rain and note exactly where it appears.
Mistakes that confuse the result
- Testing right after rain. Wet wood and wet metal hide where new water is going.
- Running the hose too hard. A fire-hose blast overflows any gutter. Use a gentle, steady flow.
- Testing the whole house at once. Work one run at a time so you know which joint is dripping.
- Forgetting to check below. Watch the bottom of each downspout as well as the trough.
- Not writing it down. By the fourth run you will forget what the first one did.
Keep a simple record
Sketch the house as a box, mark each run and downspout, and write what each test showed. Add photos with the spot circled. Keep the sketch with the date. Next fall you can repeat the tests and see what has changed, and any contractor you call can read it in a minute.
When the hose test is all clear
If every run drains, every corner is dry and the fascia is solid, the gutters are working. Look again after the first big storm and after the heaviest leaf drop over your roof. A system that passes twice a year is one you can leave alone.
When to stop testing and call
Stop and get help if you find soft fascia, a gutter that moves when touched, or water inside the house. Those are signs of damage that a hose test cannot measure, and they get worse each wet month. Bring your sketch and photos to the estimate.
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