High Performance Rainproof Ventilation Louvres > Performance of Internal Drainage System Test Sample versus Site Sample Previous Next 1m x 1m Test Sample and Details of internal drainage system (half mullion) Previous Next 5m x 5m Site Sample and Details of internal drainage system (centre mullion) BSRIA Accredited Test Reports Test reports of our Single bank ventilation louvres, Double bank rainproof ventilation louvres and Triple bank stormproof ventilation louvres. Relevance & Accuracy of Louvre Test Results BSRIA being one of the only two laboratories in the world that is fully accredited and independent, ensures that the most stringent and credible test results are derived in accordance to the latest test standards.