How to Find a Gutter Leak Before You Call Anyone
There's a drip somewhere along the front of the house every time it rains, and by the time you get outside with a flashlight it's dark and everything is wet. Here's how to find it on a Sunday afternoon with a garden hose, and how to tell the three things that look like a leak apart, because they cost very different amounts to fix.
What you need
A hose that reaches the roof edge, a helper on the ground, a ladder if you're comfortable on one (single-story only; leave two-story to us), and a dry day — which in Columbus in September is most of them.
The test
Step one: look before you spray
Walk the house and look at the ground and the wall under each gutter run. Leaks leave evidence:
- A drip stain or white mineral streak below a corner, end cap or seam: a joint leak
- A washed-out trench in the mulch along a whole run: overflow, not a leak
- Dark streaks down the fascia board behind the gutter, with the gutter itself clean: water running behind it
- Green algae or a wet patch at one spot on the siding under the gutter: a leak or overflow right above it
- A puddle at the foundation next to a downspout: the downspout, not the gutter
That takes five minutes and usually narrows it to one run.
Step two: the hose test, from the top
Start at the end of the run farthest from the downspout. Run the hose at a moderate flow into the gutter — not blasting, just steadily. Your helper watches from the ground.
Water appears at a corner or end cap within a minute — that's a joint leak. The sealant has failed. In Columbus this is almost always freeze-thaw damage; the bead lifts a little each winter until it lets go. Fix: clean to bare metal, dry, reseal with polyurethane gutter sealant. $150–$250 per corner, or a $12 tube and an afternoon if it's one corner on a single story.
Water drips from the bottom of the gutter mid-run, away from any joint — a hole. On aluminum, that's usually a screw hole from an old hanger or a spot where a ladder crushed it. On steel, it's rust, and there'll be more. Fix: a dab of sealant over a screw hole; a section replacement for a crushed spot; a replacement quote for rust.
Water takes a long time to reach the downspout, or pools in the middle — the run has sagged. Not a leak, but it will overflow there in a hard rain and freeze there in winter. Fix: re-hang and reset the pitch, $150–$300 per run.
Water reaches the downspout and backs up — the downspout is blocked. Fix: flush from the top; if that fails, take off the bottom elbow and clear it.
Step three: turn the hose up
Now open it all the way, and if you have a second hose, add it. You're simulating a summer downpour on the run.
Water goes over the front lip — overflow. Either the run is undersized, the downspout is too small, or there's only one on a long run. Not a leak. Why gutters overflow in Columbus rain sorts out which.
Water appears on the fascia behind the gutter — the water is getting in between the roof and the gutter. There's no drip edge, or the shingles stop short of the gutter, or the gutter is hung too low. This one fools everybody. From the yard it looks exactly like a leaking gutter, and people reseal every joint on the run without fixing it. Fix: a drip edge flashing, which is a roofer's job, $200–$400 an eave; or raising the gutter, which is ours.
The three look-alikes, side by side
| What you see | What it is | Who fixes it | Cost |
|---|---|---|---|
| Drip at a corner at low flow | Joint leak | Gutter crew | $150–$250 |
| Sheet over the front at high flow | Overflow — capacity or pitch | Gutter crew | $150–$300 per fix |
| Wet fascia, gutter half empty | Water behind the gutter | Roofer (drip edge) | $200–$400 |
Downspouts
Don't forget the downspout. Run the hose into the outlet and watch each elbow. An elbow that's come apart sprays the foundation instead of the extension, and on Columbus clay that's a wet basement corner in the making. Fix: re-seat the elbow and add a screw; $20 if you do it, $120–$220 if we replace the downspout and upsize it to 3x4 while we're there.
Corners on old houses
On brick homes in Clintonville, Bexley and Upper Arlington with copper or galvanized half-round gutters, a leak at a seam is a soldered joint that's cracked, not a caulked one. Sealant is a stopgap. The right fix is resoldering, and it's worth doing because the gutter will outlast anything you'd replace it with. Box gutters in the cornice are a different test again: water inside the trough means the lining has failed, and that's a reline, not a reseal.
When to stop and call
If the leak is on a second story, if you'd have to lean the ladder on the gutter, if the fascia is soft when you press it, or if the hose test shows leaks at more than two or three joints on a sectional system — stop. The last one isn't a repair anymore; it's repair vs. replacement, and it deserves both numbers on paper. Everything else, call for a gutter repair estimate and read us what the hose showed you. It'll save the first ten minutes of the visit.
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