The homeowner in Markham called us about leaking gutters. During the conversation, he mentioned he'd spent $2,000 the previous year on interior basement waterproofing — sealant on the foundation walls and a sump pump upgrade. The basement was still damp.
We looked at the eavestroughs. That was the problem.
What we found
The house had sectional aluminum gutters — the kind made from pre-cut pieces joined with connectors and sealed with caulk. Every joint was leaking. Not dramatically — you wouldn't notice from inside. But during rain, water was sheeting down the outside of the gutters at every seam, falling directly against the foundation wall.
Worse: the original install had only two downspout runs for 120 feet of eavestrough. The back of the house — which faced the slope of the yard — had a 40-foot run of gutter draining into a single downspout at one end. The other end overflowed in any moderate rain, dumping water right at the back corner of the foundation.
That corner was exactly where the basement was dampest.
Why this happens
Sectional gutters have a joint every 10 feet. Each joint is sealed with butyl caulk. That caulk has a lifespan of 5–8 years in Ontario's freeze-thaw cycles. After that, the joints open up. Resealing works for a season or two, but the gutter sections also shift as they expand and contract with temperature, eventually pulling the joints apart permanently.
One missing downspout run means water has to travel further along the gutter to find an exit. A 40-foot run generates real volume in a downpour — volume that the gutter's slope can't move fast enough, so it overflows at the low points. The overflow lands at the foundation, percolates through the soil, and pressures the basement wall.
The fix
We removed all 120 feet of sectional gutter and installed seamless 5-inch aluminum. Seamless means exactly that — each run is one continuous piece, custom-formed on site, with no joints to fail. The only seams are at corners and downspout outlets, which we rivet and seal.
We added three downspout runs where the original had two. The back of the house now has two downspouts splitting that 40-foot run in half, each directing water at least 4 feet from the foundation via extensions.
The whole job took one day.
The money math
The homeowner spent $2,000 on basement waterproofing that didn't solve the problem because the problem wasn't inside — it was on the roof edge. The eavestrough replacement cost less than the waterproofing did. Six months later, the basement was dry.
This isn't unusual. We see it a few times a year: homeowners treating basement moisture as a foundation problem when it's actually a drainage problem. Before you spend money on interior waterproofing, look up. If your gutters are leaking, overflowing, or draining too close to the house, fix that first.
Signs your eavestrough is failing
- •Visible dripping at seams during rain
- •Water staining or green algae streaks on fascia board
- •Erosion channels in the soil directly below the gutter line
- •Basement dampness that gets worse after heavy rain
- •Gutters pulling away from the fascia (the spikes or hangers are failing)
A functioning eavestrough system is the first line of defence for your foundation. It's also one of the cheapest things to fix relative to the damage it prevents.