Extensive research and development over three years revealed that no two installations would be the same due to varying roof and gutter styles, building practices, density and variety of tree species, and the natural elements of wind and rain. Many concepts were tested and evaluated before designing The Great Barrier Leaf ® (GBL)

I: Why Use Slots:

For a leaf barrier to be effective it must exclude leaves while still collecting water. Tests proved holes were inferior to slots because holes created too much peripheral water tension and result in extremely poor water collection causing water to over shoot gutters. GBL provides superior water catchment via slots up to 50 times greater than the sum total cross sectional area of downpipes.

2: Why Use An Arched Barrier:

Various profiles were tested: A perforated metal tray was placed under the roof tiles and across to the gutter bead, however, this only provided a gutter within a gutter and achieved no worthwhile benefit. A ramped profile spanning from roof tiles to gutter bead was also found to be ineffective because in moderate to heavy rainfall water would over shoot the gutter. This can cause corrosion of gardens, building foundations and run off into neighbouring properties.

The solution was to temporarily slow water velocity with an arched barrier which allowed sufficient time for water to drain through the slots.

3: Why Use High Density Polyethylene (H.D.P.E) Metal systems are too rigid for the majority of installations as numerous gaps occur between the leaf barrier and the irregular profiled roof edge, allowing excessive leaf entry. H.D.P.E. has semi-rigid and natural springing qualities and when installed as an arched profile provides positive fixing into the gutter bead and back corner of the gutter. This forces the bars between the drainage slots to press firmly against the profiled roof edge to close all the gaps.

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