Blog · Kitchener

5-inch or 6-inch eavestrough for your Kitchener home? How to tell which one the roof needs

Most single-family homes in Kitchener are well served by 5-inch K-style eavestrough, which is the residential standard. A 6-inch trough makes sense on large or steep roof planes, on long runs that can only have one downspout, and under metal roofs that shed water in a sheet. The downspout count and placement usually matter more than the trough width.

Last updated October 24, 2026 · Reviewed by the Kitchener Eavestrough team

What is the difference between 5-inch and 6-inch eavestrough?

The number is the width across the top of the trough. A 5-inch K-style trough is the standard residential size and is normally paired with 2-by-3-inch downspouts. A 6-inch trough is wider and deeper and is paired with 3-by-4-inch downspouts, so the whole system, trough and outlets together, carries considerably more water before it overflows. Both are formed on site from the same pre-finished aluminum coil, hang on the same kind of hidden hangers, and come in the same colours. The 6-inch profile sits a little taller on the fascia, which is noticeable on a low bungalow and invisible on a two-storey.

The useful way to think about it is capacity in a hard rain. The trough has to hold what the roof sheds long enough for it to reach an outlet, and the outlet has to swallow it as fast as it arrives. If either part is undersized, the water goes over the front lip or over the back onto the fascia, and from there to the foundation.

Which Kitchener roofs need 6-inch eavestrough?

A 6-inch system is the better call in four common situations, and most Kitchener houses have none of them.

• Large or steep roof planes. A steep gable delivers water to the eave faster than a shallow one, and a big roof plane simply delivers more of it. The tall two-storeys through Huron Park with steep front gables over the garage are the local example.
• Long runs with a single outlet. On a rear eave where there is only one place a downspout can discharge, a wider trough buys time for the water to travel the whole run. Adding a second outlet is usually the better fix, but where that is not possible the larger trough compensates.
• Metal roofs. Steel roofing sheds water in a sheet that can overshoot a 5-inch trough entirely. Farmhouses and newer builds around Breslau with steel roofs are where this comes up.
• Upper roofs draining onto lower ones. When a second-storey roof dumps onto a porch or garage roof, the lower trough is catching two roofs at once and should be sized for both.

A postwar bungalow in Forest Heights or Stanley Park with a shallow roof and a downspout at each end of every run does not need any of this. A 5-inch trough on sound fascia with screwed hangers will handle it, and the extra money is better spent on heavier gauge aluminum and on the fascia behind it.

Why the downspout count matters more than the trough size

Most overflowing eavestroughs in Kitchener are short of outlets, not short of width. The builder's habit on newer houses is one downspout per run, dropped at whichever corner was closest, and on a long rear eave that means the water at the far end has a long way to travel before it can leave. Cutting a second outlet into the low end of a sound trough is one of the cheapest and most effective jobs there is, and it fixes an overflow that a 6-inch upgrade would only reduce. As a rough rule the contractor we book for Kitchener wants a downspout at each end of any run much over 12 metres (about 40 feet), and the trough pitched to deliver to both.

Placement is the other half. The City of Kitchener's own guidance to homeowners, repeated in its winter flood-preparation notices, is that there should ideally be two metres of open space below a downspout, that the water should land on grass or garden, and that downspouts should not be directed toward neighbouring properties, walkways or parks. On the narrow side yards of Stanley Park that often rules out the obvious corner and sends the downspout to the back of the house. Picking those discharge points first, then sizing the trough and outlets to reach them, is how a system gets designed rather than copied.

Does a bigger trough stop ice and overflow in winter?

Not on its own. Ice forms in a trough that holds standing water, and standing water comes from poor pitch and pulled hangers, not from width. A 6-inch trough with a sag in it holds a bigger bar of ice than a 5-inch one with the same sag. Where an eave builds ice every winter the cause is usually heat escaping into the attic through a closed soffit and thin insulation, which no trough size fixes. The right answer there is vented soffit and proper pitch, and the fascia and soffit page covers it.

Where the water goes once it leaves the trough

Whichever size you choose, the Region of Waterloo's Sewer Use By-law 21-036 prohibits roof and storm water from being discharged into the sanitary sewer, so a downspout on an older Kitchener house that disappears into a pipe at grade has to be traced before a new one is connected to it. Ontario's guidance on surface water and drainage disputes also draws a line that matters: rain that runs naturally across your land is one thing, but water you have collected in eavestroughs and downspouts carries an obligation to discharge it where it will not cause problems for the property downhill. A larger trough collects more water, which makes the discharge plan more important, not less.

If you are considering a rain barrel, Kitchener offers residential stormwater credits of 20, 30 or 45 per cent of the monthly stormwater fee for capturing roof water in barrels, cisterns, rain gardens, infiltration galleries or permeable pavers, in tiers of 200 to 800 litres, 801 to 3,200 litres and more than 3,200 litres. The downspout feeding a barrel should be placed so the barrel sits level and its overflow runs to grass, which is a decision for the day the trough is hung.

What this means for your quote

Ask the quote to state the trough size and gauge, the downspout size and count, where each one discharges, and the hanger type and spacing. If a quote proposes 6-inch everywhere on a plain bungalow, ask why; if it proposes 5-inch with one outlet on a 15-metre rear run under a steep roof, ask about a second downspout. The contractor we book for Kitchener sizes each run on the site visit rather than quoting one profile for the whole house, and the seamless installation page explains what a proper hang includes. For how trough size moves the total, see the Kitchener eavestrough cost guide, or describe your roof here and a site visit will settle it.

Sources

• Take steps today to manage the melt and reduce the risk of flooding - City of Kitchener
• Stormwater credits - City of Kitchener
• Sewer Use By-law 21-036 - Region of Waterloo
• Surface water and drainage disputes - Government of Ontario