Most homeowners don't think about their gutters until something goes wrong. The problem? By the time you notice visible damage, the clog has often been causing invisible harm for weeks or months. These 7 warning signs will help you catch the problem early — before it becomes expensive.
Sign 1: Water Overflows During Rain
This is the most obvious sign, and the one most homeowners catch. If you see sheets of water cascading over the edge of your gutters during a rain shower rather than flowing to the downspout, your gutters are clogged. Even a partial clog can overwhelm the system during heavy Ontario rain events.
Where this water goes matters enormously. It typically flows directly down your siding, pools at your foundation, or erodes your garden beds. None of those are good outcomes.
Sign 2: Gutters Are Sagging or Pulling Away from the Fascia
Gutters are designed to be lightweight when clean. A clogged gutter filled with wet, compacted leaves can weigh hundreds of pounds. This weight causes the hangers and spikes to pull free from the fascia board, creating a sag or outward lean.
If you see a section of gutter visibly drooping or pulling away from the roofline, you're looking at both a clog problem and a structural problem. The clog needs clearing; the hangers need replacing; and the fascia may already be showing water damage.
Sign 3: Plants Are Growing in Your Gutters
This sounds extreme but it's more common than you'd think, especially on north-facing roof sections where debris stays moist. Maple samaras (the winged seeds), acorns, and pine cones all carry seeds that germinate readily in the wet, composting debris inside a clogged gutter. If you can see greenery sprouting from your gutters from the ground, the clog has been there for at least a season — and you likely have a drainage problem already underway.
"We've found fully established grass, weeds six inches tall, and once — memorably — a small tree sapling growing out of a second-floor gutter in Cambridge."
— Devon, D&D Home Services Co-Founder
Sign 4: Dark Stains or Streaks on Your Siding
Those dark vertical streaks running down your siding below the gutter line aren't just cosmetic. They're caused by overflow water picking up tannins from decomposing organic matter in the gutter. Called "tiger striping," these stains are an early warning of overflow. If you're seeing fresh stripes after every rainstorm, your gutters need attention immediately.
Note: These stains can also be caused by oxidation of the gutter's paint (especially on older aluminum gutters). The difference is that oxidation staining is uniform, while overflow staining follows specific overflow paths.
Sign 5: Increased Pest Activity Around Your Roofline
Clogged gutters are like a five-star hotel for pests. Standing water attracts mosquitoes (breeding ground). Decomposing organic matter attracts carpenter ants, earwigs, and centipedes. Moist, sheltered gutters are ideal nesting locations for wasps, hornets, and in some Ontario neighbourhoods — birds and squirrels.
If you're noticing more pest activity around your roofline or eaves than usual, a gutter inspection is worth adding to your pest control plan.
Sign 6: Basement or Foundation Moisture
This is the most expensive sign to ignore. When gutters overflow, water consistently pools against your home's foundation. Over time, this creates hydrostatic pressure that pushes moisture through foundation cracks. The symptom shows up as damp basement walls, efflorescence (white mineral deposits), or actual water seeping in during rain events.
Important: If you're experiencing basement water entry, have your grading and gutters inspected before investing in interior waterproofing solutions. Fixing the source (drainage) is almost always more cost-effective than treating the symptom (water entry).
Sign 7: Visible Debris from Ground Level
If you can see twigs, leaf mats, or a "mud line" of debris visible above the gutter edge from the ground, the gutters are at or past capacity. This is particularly common after Ontario's fall leaf season. A quick scan of your roofline from the yard after leaf drop is one of the easiest maintenance checks you can do.
What to Do If You Notice These Signs
If you're seeing one or more of these warning signs, act before the next significant rain event — not after. A professional gutter cleaning typically takes 1–2 hours for an average home and costs a fraction of the damage a single overflow event can cause.
D&D Home Services serves Kitchener, Waterloo, Cambridge, and Guelph. We include a full visual inspection with every gutter cleaning, checking for damaged hangers, improper pitch, joint separation, and signs of water damage on your fascia.
Quick Summary: 7 Signs to Watch For
- Water overflowing during rain instead of draining to downspouts
- Gutters sagging or visibly pulling away from the roofline
- Vegetation growing from gutter troughs
- Dark vertical stains or "tiger stripes" on siding below gutters
- Increased wasp, ant, or mosquito activity near eaves
- Damp basement walls or foundation moisture after rain
- Visible debris mat from ground level
