Proctor Air® is an air and vapour permeable, highly water resistant roofing underlay. Its characteristics allow even very complex pitched roofs to breathe, without the need for air gaps or secondary venting. The high performance meltblown core at the heart of Proctor Air allows natural air movement to ‘supercharge’ the passage of moisture vapour from the roof space, making the formation of condensation in the roof space virtually impossible. Vapour permeable Fully air permeable Highly water resistant Wind Uplift Resistance Complies with BS5534 More uniform airflow than vents No VCL required 15 year warranty BBA Certified You can find full details and information& certification downloads for Proctor Air here: https://proctorgroup.com/products/pro...