How to Find a Gutter Leak Before You Call Anyone
"The gutter leaks" covers about five different problems, and they don't cost the same to fix. Twenty minutes with a garden hose on a dry afternoon will tell you which one you've got, and you'll get a more accurate price over the phone if you can describe it. Here's how to do the test and what each result means.
What you need
A hose long enough to reach the roofline, a ladder you can safely stand on (or a helper on the ground while you're up), and a dry gutter. Do it after two dry days, because you're looking for where water appears, and a gutter that's already wet everywhere tells you nothing. Clear any obvious debris first — you're testing the gutter, not the leaves.
The test, in order
1. Run water into the far end of the run, away from the downspout, at a gentle flow. Watch the run from the ground.
- Water reaches the downspout and comes out the bottom: pitch and downspout are fine. Move on.
- Water pools in the middle and doesn't move: the run has sagged. That's a re-hang, $150–$300.
- Water runs toward the wrong end: the run is pitched backward, usually because a hanger at the downspout end has let go. Same fix.
2. Increase the flow to a full open hose and watch the corners. A hose is roughly a quarter-inch of rain on a small roof, so this is a fair test.
- A drip from the underside of a corner or an end cap: the seam sealant has failed. That's the most common leak in Pittsburgh, opened up by freeze-thaw, and it's a clean-and-reseal, $150–$250.
- A drip from a spot along the bottom of the run, not at a seam: a hole. On aluminum, a screw hole from an old hanger or a puncture from a ladder; on steel, rust. A screw hole is a $150 patch. Rust pinholes mean the run is done.
3. Keep the hose running and look at the downspout. Water from the elbow joints or the seam down the back of the downspout means the elbow has separated or the seam has split, often from ice last winter. $120–$220 to replace the downspout.
4. Now look behind the gutter. With water running, check the fascia above and behind the gutter for wetness. If the fascia is wet and the gutter isn't full, water is getting in behind the gutter from the roof — the shingles stop short, there's no drip edge, or the gutter is hung too low. That isn't a gutter leak at all; it's a roof-edge detail, and it's worth knowing before you pay someone to reseal a gutter that isn't leaking.
What overflow looks like, so you don't mistake it
If the water only goes over the front lip when the hose is fully open, and nothing drips from underneath, the gutter isn't leaking. It's overwhelmed. Either the downspout is too small, there's only one on a long run, or the gutter is undersized for the roof. That's a capacity problem with its own set of fixes, covered in why gutters overflow in Pittsburgh rain.
The results table
| What you saw | What it is | Typical fix |
|---|---|---|
| Water pooled mid-run | Sag, pitch gone | Re-hang, $150–$300 |
| Drip at a corner or end cap | Failed seam sealant | Clean and reseal, $150–$250 |
| Drip from a spot mid-run | Hole — screw, puncture or rust | Patch $150, or replace the run if rusted |
| Water from downspout joints | Split elbow or seam | Replace downspout, $120–$220 |
| Fascia wet, gutter not full | Water behind the gutter | Drip edge or re-hang; roof detail |
| Over the front lip only | Capacity, not a leak | Bigger downspout, second downspout, or 6-inch |
The one you can't test with a hose
If your house was built before about 1930 and the gutter is built into the roof edge behind the cornice, a hose test tells you the outlet works or doesn't, and not much else. Box gutter leaks show as peeling paint on the cornice and stains on the ceiling inside, and they're diagnosed by opening the gutter. That's a different job; the box gutter page explains it.
Doing it safely
A ladder and a running hose is a two-person job: one person up, one on the ground holding the ladder and watching for drips. Set the ladder on firm, level ground with a standoff so it doesn't rest on the gutter. Keep the hose clipped or held so it can't pull you sideways. On a two-story house, test the first-story runs yourself and leave the upper ones to someone with the right equipment.
Marking what you find
Use painter's tape or chalk to mark each leak on the gutter or the siding below it, then take a photo. Write a short note for each one: which side of the house, which corner, and what you saw. A sketch of the house with each mark on it takes two minutes and saves a lot of explaining.
Stopgaps worth doing
- A dripping corner: dry it and run a bead of gutter sealant along the inside of the joint. It won't hold long on a dirty or damp joint, but it buys time.
- A separated downspout elbow: push it back together and fasten it with two short sheet-metal screws.
- A run pulling away: one hidden hanger screwed into sound fascia can hold it until it's properly re-hung.
- Water at the foundation: a temporary extension or splash block moves it away until the real fix.
Fixes not worth doing
- Roofing tar on aluminum. It cracks in the cold and makes a proper reseal harder.
- Tape over rust holes on steel. It peels off by spring.
- Caulk on the outside of a seam. The water is inside the joint, so that's where the sealant goes.
When the stain is inside the house
If the stain is on a ceiling or an inside wall, a gutter is only one suspect. Flashing at a chimney or a dormer, a roof leak, or a failed built-in gutter can all show up in the same place. If the hose test finds nothing at the gutters, it's time for a roofer to look.
Leaks by season
Each season shows a different kind of leak. In spring, after the ice lets go, look for corners and seams opened by freeze-thaw and for elbows split by a frozen downspout. In summer, hard rain shows capacity problems and leaks at the outlet, where the downspout joins the trough. In fall, a drip that appears only after the leaves come down is often a clog backing water into a seam that's normally dry. In winter, water dripping from the middle of a run on a sunny day can be meltwater from an ice dam rather than a gutter leak at all. Matching what you saw to the season helps narrow it down before you test.
What to tell the contractor
When you call, describe the house and the leak in a few lines: how old the house is, what the gutters are made of, which side the leak is on, whether it's at a corner, a seam, mid-run or the downspout, and what the hose test showed. Send the photos. That's usually enough for a rough idea of the fix and the price before anyone visits. Ask what the visit will include, whether the price is likely to change once someone is on the ladder, and how long the written estimate holds. A clear answer to all three is a good sign.
When to stop and call
Stop if the ladder has to lean on the gutter to reach, if the eave is more than one story above where you're standing, or if you find the fascia is soft when you press it. All three are common on Pittsburgh's hillside houses and all three are how people get hurt. Note what you found — "corner drip on the front left, water pooling on the back run" — and pass it on when you book; the gutter repair visit will be shorter and the estimate more accurate.
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