Fall Calculation

In roofing and plumbing, "fall" refers to the controlled slope applied to a horizontal or near-horizontal surface to ensure water flows in the desired direction by gravity. Fall is typically expressed as a ratio — for example, 1:500 means the surface drops 1mm for every 500mm of horizontal run. Different components require different falls: standard eaves gutters typically require a minimum fall of 1:500, box gutters require 1:200, and flat roof membranes require a minimum of 1:100. Calculating the correct fall involves measuring the horizontal distance between the high point and the discharge point, then applying the specified ratio to determine the total drop. For example, a 12-metre gutter run with a 1:500 fall would need a total drop of 24mm from the high end to the outlet. This fall must be achieved while ensuring the gutter maintains a consistent appearance along the fascia line and does not drop below the roof edge at the low end. In Gippsland, correct fall calculation is critical due to the region's heavy rainfall events. Insufficient fall leads to water ponding in gutters and box gutters, which causes overflow, accelerated corrosion, and eventual leaking. Town & Country Roofing uses laser levels and precise measurements to ensure every gutter run achieves the correct fall, providing reliable drainage even during intense downpours.