6-Inch vs 5-Inch Eavestroughs for Ottawa Thunderstorms

Six-inch eavestroughs handle significantly more water than standard 5-inch gutters, and for many Ottawa homes — especially those with steep roofs or large roof areas — they're the smarter choice. Ottawa's summer thunderstorms can dump 25 to 50 millimetres of rain in under an hour, and those peak flow rates are where the difference between 5-inch and 6-inch gutters becomes obvious.

The Capacity Difference Matters

A standard 5-inch K-style eavestrough handles approximately 1.2 gallons of water per foot of gutter. A 6-inch K-style handles roughly 2.0 gallons per foot — that's nearly 40 percent more capacity from just one inch of additional width. During Ottawa's intense July and August thunderstorms, that extra capacity prevents the overflow that sends water cascading down your siding, eroding your landscaping, and pooling against your foundation.

The upgrade makes the most sense for specific situations. Steep-pitched roofs (8:12 slope or greater) accelerate water flow dramatically, and a 5-inch gutter can't capture fast-moving runoff during heavy rain. Large roof areas that funnel into limited gutter runs — common on Ottawa homes with complex rooflines, dormers, or valleys — concentrate more water than a 5-inch system was designed for. Homes surrounded by mature trees, particularly in neighbourhoods like the Glebe, Rockcliffe Park, and Old Ottawa South, benefit because 6-inch gutters handle partial debris blockage better than 5-inch systems that clog and overflow at the first handful of leaves.

The cost difference is modest. In Ottawa, 5-inch seamless aluminum runs $8 to $15 per linear foot installed, while 6-inch seamless aluminum costs $10 to $18 per linear foot. On a home with 150 linear feet of gutter, you're looking at roughly $300 to $600 more for the wider system — a small premium for significantly better performance. The 6-inch system also pairs with 3x4-inch rectangular downspouts instead of the standard 2x3 size, further improving drainage capacity.

There are a few considerations before upgrading. Six-inch eavestroughs are slightly more visible from the ground, which matters on heritage homes in districts like Sandy Hill or New Edinburgh where exterior appearance may be regulated. Your existing fascia board needs to be in good condition and wide enough to support the larger profile — most Ottawa homes with standard 1x6 fascia accommodate 6-inch gutters without modification.

For a typical Ottawa bungalow or two-storey home, 5-inch gutters are adequate when properly sloped with sufficient downspouts. But if you're replacing your eavestroughs anyway and your home has any of the risk factors above, the 6-inch upgrade is well worth the modest extra cost. An experienced contractor can assess your roof area and recommend the right size — browse eavestrough professionals through the Ottawa Construction Network directory at justynrookcontracting.com.