Your eavestroughs collect water. Your downspouts carry it away. When a downspout clogs, the entire system fails — water backs up in the gutter, overflows at the foundation line, and pours directly into the most vulnerable part of your home. A single clogged downspout during a heavy Toronto rain can dump hundreds of litres of water against your foundation in an hour.
5 Signs Your Downspout Is Clogged
💧 Gutter overflow: Water pours over the top during rain instead of flowing to the downspout. The eavestrough fills up because water can't exit.
🚫 No bottom flow: During rain, nothing comes out the bottom. Complete blockage — water is stuck somewhere in the pipe.
💦 Seam leaks: Water squirts from downspout joints. Internal pressure from a clog forces water out of every gap.
📐 Gutter sag: Eavestrough droops near the downspout connection. Standing water adds weight — water weighs 8.3 lbs/gallon.
🏠 Foundation pooling: Water puddles at your foundation during rain even though you have eavestroughs. The downspout isn't directing water away.
What Clogs Downspouts in Toronto
- Leaf compression: Leaves enter the eavestrough, flow to the downspout entrance, and compress into a dense plug at the first elbow (typically 6-12 inches from the top). Maple leaves are the worst — they're large, flat, and interlock like shingles when compressed by water flow.
- Shingle grit: Toronto's freeze-thaw cycles (80+ per winter) grind shingle granules loose. These fine, heavy particles wash into eavestroughs and settle at downspout elbows. Over 2-3 years, they form a concrete-like sediment plug that water can't penetrate.
- Bird nests and animal debris: The downspout entrance (at the top of the pipe) is a favourite nesting spot for sparrows and starlings. They build nests in the elbow, completely blocking water flow. Spring (March-May) is peak nesting season.
- Ice plugs: In winter, meltwater enters the downspout and refreezes mid-pipe. Each freeze-thaw cycle adds another ice layer until the downspout is completely frozen solid. This is why downspout ice expansion cracks aluminum — frozen water expands 9%.
- Underground drain collapse: Many Toronto homes connect downspouts to underground drains (weeping tile or storm sewer). These buried pipes are 30-60+ years old in many neighbourhoods — they crack, collapse, or fill with tree roots. The downspout appears clogged but the actual blockage is 10-20 feet underground.
How to Clear a Clogged Downspout
- Garden hose test: Insert hose into top of downspout. Run full pressure. If water flows out the bottom normally, no clog. If water backs up and overflows from the top, clog confirmed.
- Tap the pipe: Walk along the downspout and tap with your hand or a screwdriver. A clogged section sounds solid/dull. An empty section sounds hollow. This locates the clog.
- Pressure flush: Insert hose from the bottom, push upward toward the clog. Water pressure from below often dislodges debris better than gravity.
- Plumber's snake: For stubborn clogs (shingle grit cement, compressed leaf plugs), a drain snake breaks through the blockage. Feed from the top, rotate through elbows.
- Disassemble: If the clog is at an elbow (most common), remove the elbow section, clear manually, and reattach. Most downspout sections are held together with sheet metal screws — removal takes 5 minutes.
Underground drain warning: If water flows freely through the above-ground downspout but pools at the base, the underground drain is blocked. DO NOT try to clear underground drains yourself — you can crack fragile clay/concrete pipes, send a snake into your weeping tile system, or damage storm sewer connections. This requires a licensed plumber with a camera scope ($200-$500). Many Toronto homes built before 1970 have clay underground drains that have already partially collapsed — the only fix is excavation and replacement ($3,000-$8,000).
Downspout extensions save foundations: Even when your downspout is clear, if it dumps water right at your foundation wall, you're creating a problem. The discharge point should be at least 4-6 feet from the foundation. Options: rigid extensions ($10-$20), flexible roll-out extensions ($15-$30, unroll automatically during rain), or underground drainage to a pop-up emitter in the yard ($200-$500 installed). The $10 rigid extension is the single best foundation protection investment you can make.
MANTLE includes downspout flushing: Every eavestrough cleaning includes full downspout flushing — we run water through every downspout and confirm flow from the bottom. If we find a clog, we clear it as part of the standard service. No surprise charges. We also check discharge points and recommend extensions if your downspouts dump too close to the foundation.
Eavestrough + Downspout Cleaning
Downspout flushing included in every eavestrough clean. No surprises. No extras. All-inclusive.
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