The quote offers a six-inch upgrade. It sounds like a sensible answer to an overflowing five-inch gutter. It might be, but the question is where the extra water goes next.

Buying a bigger trough while leaving the bottleneck untouched is a very polished way to keep the same problem.

Size the route, not just the front edge

Amerimax's drainage sizing guidance links gutter selection with downspout size, roof area, and rainfall. Its product guidance is useful for understanding the system; use a design appropriate to the actual Ontario property and supplied components.

The roof area feeding one run matters more than the overall house footprint. A valley or an upper roof discharging onto a lower section can concentrate flow in a small area.

Ask what the upgrade includes

Quote itemWhat to clarify
Trough size and profileWhat capacity is needed for this roof section?
Outlets and downspoutsWill their number or size change with the trough?
Slope and supportsHow will water reach the outlets without persistent pooling?
Fascia conditionIs the attachment surface sound, and who repairs it?
DischargeWhere does the water go after leaving the downspout?

Gentek's eavestrough system is another reminder that the visible gutter is one part of a product system. Compare compatible parts and an installation scope, not nominal width alone.

Separate sizing from maintenance and defects

A clogged outlet, sagging run, or poor connection can overflow even when the trough is large enough. On one rear run, water spilled at the middle while the downspout carried very little. The assessment found a low section holding water away from the outlet. Simply fitting a wider trough to the same line would have carried the defect into the new work. Have the levels, outlet and fascia checked together.

Avoid a universal percentage claim about how much more water "six-inch gutters" handle. Profile, slope, outlet arrangement, and rainfall conditions affect the result. Ask the installer to explain the selection for your roof instead.

Keep the discharge off the wrong place

An improved collection system should not deliver more water onto a walkway, neighbouring property, or back towards the basement. Walk the proposed discharge route with the installer and show them the gate, winter walking route, window wells, and any spot that already stays wet. Include the final route in the proposal and check local discharge requirements. The downspout extension still has to work when the gate is open.

Ask the installer to show you the outlet and discharge changes beside the proposed gutter upgrade. You want to know where the water will leave the roof and where it will land. If the explanation stops at 'six-inch is better,' the quote still needs another conversation.