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.
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. Tell us what you found — "corner drip on the front left, water pooling on the back run" — and the gutter repair visit will be shorter and the estimate more accurate.
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