5-Inch vs 6-Inch Eavestroughs for Ottawa Homes

For most standard Ottawa homes with moderate roof pitches and typical lot sizes, 5-inch K-style eavestroughs are the right choice and the industry default. However, if your home has a steep roof pitch, a large roof footprint, or limited downspout locations, upgrading to 6-inch eavestroughs is a smart investment that pays for itself by preventing overflow during Ottawa's intense summer thunderstorms and heavy spring snowmelt.

How to Decide Between 5-Inch and 6-Inch

The decision comes down to how much water your roof collects and how quickly your eavestrough system can drain it. A 5-inch K-style eavestrough holds approximately 1.2 gallons per linear foot, while a 6-inch K-style holds roughly 2.0 gallons per linear foot — a 67 percent increase in capacity. That difference matters during Ottawa's heavy rainfall events, which can deliver 25 to 50 millimetres of rain per hour during summer convective storms.

Choose 6-inch eavestroughs if your home has any of these characteristics: a roof pitch steeper than 6/12, which accelerates water flow and overwhelms smaller gutters; a total roof area exceeding 2,500 square feet draining to one side; eavestrough runs longer than 40 feet to a single downspout; or valley configurations that concentrate water from multiple roof planes into one gutter section. Homes in newer Ottawa subdivisions like Riverside South, Findlay Creek, and Stittsville often have larger footprints with complex rooflines that benefit from 6-inch gutters.

The cost difference between 5-inch and 6-inch seamless aluminum in Ottawa is modest — typically $1 to $3 more per linear foot, which translates to roughly $150 to $500 extra for a whole-house installation of 150 to 180 linear feet. Given that the 6-inch system dramatically reduces the risk of overflow and the resulting fascia rot, foundation moisture, and landscape erosion, the upgrade is excellent value when the roof warrants it.

One important consideration specific to Ottawa is ice dam management. Larger eavestroughs can accommodate more ice and snow buildup before the system becomes completely blocked, giving you a wider margin during the 50-plus freeze-thaw cycles Ottawa experiences each winter. Six-inch gutters paired with hangers at 18-inch spacing create a more robust system that stands up to heavy wet snow loads without pulling away from the fascia.

Downspout sizing should match your eavestrough choice. Five-inch gutters pair with 2x3 inch downspouts, while 6-inch gutters should use 3x4 inch downspouts to maintain proper drainage capacity. Undersized downspouts on oversized gutters create a bottleneck that defeats the purpose of the larger gutter.

Ask your contractor to calculate the drainage area for each eavestrough run and recommend the appropriate size based on your specific roof geometry. A good contractor will not just default to one size for every home. You can find eavestrough professionals familiar with Ottawa's requirements through the Ottawa Construction Network directory at justynrookcontracting.com.