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 crews do, and it is 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 we can price over the phone within a range, and it turns a two-visit job into one. Bring your notes and photos when you book a repair.
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 cleaning visit includes every test above from our ladder, and it costs less than an emergency room.
Need gutter work in Portland?
Call for a free estimate. Mon–Sat 7am–7pm.