The maximum length of an eaves trough gutter depends on a number of factors pertaining to a particular site. At the end of the day, it’s a matter of using good judgement in our experience. Guidelines provided by a Building Codes Board provide a solid platform, and we summarise them here.

The Basics of Every Eaves Trough System

An eaves trough is a gutter fixed to a fascia, or eave on a house, to catch rainwater running off the roof. Hence, its maximum length must be seen in context of the entire roof structure. We should not underestimate the weight of the water these gutters carry, and always ensure that they rest on sturdy brackets.

Factors Influencing the Size of an Eaves Trough

The length and cross-section of an eaves trough determines the amount of water that it can hold at any one time. And this in turn depends on the rainfall patterns in the area concerned. The slope of the roof adds a further dimension, because it influences the rate at which the water flows down.

We can calculate these factors, once we know the catchment area of the roof discharging into the system. This information, plus the anticipated maximum rainfall intensity, enables us to determine an eaves trough size capable of accepting the anticipated flow.

Eaves Trough Length Versus Number of Down Pipes

An eaves trough could theoretically be any length, provided it was strong enough, and there was no debris obstructing it. However the reality is somewhat different. For this reason, the Building Codes Board recommends that a single down pipe should not serve more than a 12 meter / 40-foot gutter length.

We worked on a building once with a long roof edge, where it was impractical to install gutters in one section. And so we split the job into three eaves troughs, each with their own down pipe. We avoided the dubious practice of simply splicing the sections together, because we knew the joints would inevitably leak from expansion and contraction.

And so we made each section fully independent, with its own down pipe and end caps. That way we knew the job would last, because these adaptions would mitigate against the gutters buckling. This is a great example of the trouble we go to at Valiant Exteriors in Calgary. We live in the city, and we want to be able to drive past every one of our jobs proudly.

More Information

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