How to Find a Gutter Leak Before You Call Anyone
Water dripping off the gutter during a storm can be four different problems, and three of them are not leaks. Sorting them out takes a garden hose and a dry afternoon, and it changes what you ask for when you call. A leak is a $150–$250 reseal. Overflow is a sizing fix. Water behind the gutter is a roofing detail. A separated downspout is a $20 strap. Ten minutes with the hose tells you which.
What you need
A hose, someone to hold it or a spray nozzle you can lock on, and a ladder if you want to look closely. Pick a dry day so the only water on the house is yours. Late morning is good; the sun on the fascia shows drips clearly.
Step 1: run the gutter, not the roof
Put the hose in the gutter at the end farthest from the downspout and let it run at moderate flow for two minutes. Do not spray the roof yet. Walk the run and watch.
Water dripping from a corner or an end cap. That is a sealant leak at the miter. The joint has cracked after ten Florida summers of expansion and contraction. Reseal, $150–$250. This is the most common gutter leak in Jacksonville by a wide margin.
Water dripping from a spot mid-run on sectional gutters. A seam between two sections. Reseal if there is only one; if three or four seams are weeping, the system is telling you it is done, and repair vs. replacement covers that call.
Water dripping mid-run on seamless gutters. Rare. Usually a screw hole from an old hanger or a guard, or a puncture from a fallen limb. A dab of sealant.
Water pooling in the middle and not reaching the downspout. Not a leak. Pitch has been lost and the run needs re-hanging. Standing water plus mosquitoes in August is the same diagnosis.
Water reaching the outlet and backing up. A clog at the top of the downspout, almost always pine straw. Flush it from the top with the hose at full pressure.
Step 2: run the downspout
Now put the hose directly into the downspout outlet. Water should come out the bottom within seconds. If it dribbles or backs up, the plug is lower down, often at the bottom elbow where it turns out to the extension. If water sprays out at the elbow joint at the top of the downspout, the elbow has separated from the outlet or the strap has let go. That is a $20–$80 fix and it looks exactly like a gutter leak from the ground.
Step 3: spray the roof edge
Only now spray water onto the roof just above the gutter, so it runs off the shingles into the gutter the way rain does. Watch the fascia behind and below the gutter.
Water running down the fascia behind the gutter. The gutter is fine. The roof has no drip edge, or the shingles stop short of the gutter, and water is going behind. On 1960s–80s block homes in Arlington, Lakewood and the Westside this is common after a re-roof where nobody added the flashing. It is a roofing fix, a strip of eave drip edge, and it is the reason the fascia is rotting behind a gutter that never leaked.
Water shooting over the front of the gutter. With a hose you should not be able to overflow a gutter. If you can, the gutter is pitched backward or badly undersized. Rare with a hose, common in a real storm; why gutters overflow sorts that out.
Reading the evidence without a hose
If you would rather look than test, the house keeps records:
| Clue | What it means |
|---|---|
| Green or black stain on the fascia below one corner | Corner leak, months old |
| Stain along the whole fascia, gutter clean | Water behind the gutter; drip-edge problem |
| Crater in the mulch under the downspout | Extension missing, not a leak |
| Crater in the mulch under a corner | Corner leak or overflow at that corner |
| Silt line in the gutter mid-run | Standing water; pitch lost |
| Rust streak from a hanger | Hardware failing; re-hang coming |
| Mosquitoes rising from the gutter at dusk | Standing water for a week or more |
What to tell us
When you call for gutter repair, say which of these you found. "Corner leak, front left, and the downspout on the back right sprays at the top elbow" gets you an accurate price over the phone and a crew that brings the right parts. We still check every run from the ladder when we arrive, because the corner that drips is often next to the soft fascia that does not, but you will already know roughly what you are looking at, and that is worth more than most people think when a contractor is standing in the driveway with a number.
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