The m3/h flow rate per lapVent - Building Research Establishment test
Out-flow = 11,326 mm2 at 10pa.
In-flow = 10,540 mm2 at 10pa.
Flap closes at 70m3/h and rest open under normal pressures
The free airflow calculating area is confirmed as in the order of 20,000mm2
Leading the field: lapVent is the first product on the market to undergo this
stringent type of testing - in the future others will have to follow suit.