The exclusive Alu-Perf technology is the result of extensive research and development. The product has 489 holes every 19 inches (48 cm). This allows water to drain at the same rate as a 2 in. x 3 in. (5 cm x 7.5 cm) downspout.
Rigorous testing by an independent certification agency has proven that Alu-Rex products can drain over 32.9 in. (836 mm) of water an hour over a length of 20 feet (6 m). And with 200,000,000 feet (60,960,000 metres) of Alu-Rex products installed around the world, the figures speak for themselves...
Note: The highest amount of rainfall ever recorded worldwide was 12 in. (305 mm) of water in one hour (Holt, MO, 1947). In comparison, the 1996 Saguenay flood in Quebec was triggered by 11 in. (275 mm) of rain in three days. Alu-Rex products would have been able to handle all that rain in just one hour and three times more!
Overflow is usually caused by the eavestroughs themselves (not wide enough or deep enough for the roof surface) or the downspouts (insufficient number for the roof's surface). It is important to make sure there are enough downspouts to avoid this problem. For this purpose, you need to keep in mind that one downspout is enough to drain the equivalent of a 600 sq. ft. (56 m²) roof.
In short, if you don't have backflow problems with your current gutters in heavy rainfalls, the Gutter Clean System® and T-Rex® won't create them.