Driving Rain Index (DRI) Test for Rooflights.

The first meaningful DRI standard for rooflight domes and barrel vault rooflights.

Extreme weather events, sometimes with devastating consequences have significantly increased in recent years. Our buildings must withstand the effects of these storms, and so too must the components used in their construction.

Using their technical expertise and as a "leader in innovation", Lamilux have developed a brand new testing method, together with the Institute of Industrial Aerodynamics (I.F.I.).

The product standards for rooflight domes and barrel vault rooflights: BS EN 1873 & BS EN 14963, both only require for the testing of water tightenss without the effect of wind, but is this a realistic approach?

Until now, no specific test existed to substantiate the effects of driven rain on rooflight domes or barrel vault rooflights, but this is now possible with our newly developed testing method.

The Institute of Industrial Aerodynamics have many years of experience of testing the effects of very extreme weather on similar products, such as windows and curtain walling – all of which have standardised tests for water tightness, and they drew upon this knowledge to define the testing criteria for rooflights.

The result: for the first time there is now a comparable and measurable safety standard, which allows the driving rain index (DRI - Driven Rain Index) to be calculated for rooflight domes and barrel vault rooflights. The DRI Test provides verified information on the combined effects of wind and rain on a rooflight including at the critical junctions, such as the opening vents.

The test involves placing the rooflight in a wind tunnel, with the wind speed set to 115km/h (71.5 mph), and the water velocity set to just over 7.5 litres per minute/m² (450 litres per hour/m²).

Actual test results of our F100 Rooflight Dome:

DRI Test Criteria for Rooflight Dome

We can therefore conclude that our rooflight domes and continuous barrel vault rooflights are independently tested and certified as watertight, even in extreme storm conditions.

In order to define a minimum DRI requirement to this new standard, we declare that all rooflight domes and continuous barrel vault rooflights should achieve a DRI > 3.0 m²/s.

Our rooflights far exceed this minimum requirement, and both achieve a DRI of > 14 m²/s.

A PDF copy of test results can be viewed by following these links: