Created with Eselt - eBay Listing Template Editor eBay.co.uk Give us a call Send us a message Created with Eselt - eBay Listing Template Editor - Our Store - Seller Profile - Feedback - About us - Contact Created with Eselt - eBay Listing Template Editor CROMAR Protect1F Roof Underslating Felt Non-Breathable Membrane 1m x 45m Roll DESCRIPTION: A Non Vapour Permeable ( non breather ) membrane for use under slating and tiled pitched roofs. Introduction: Protect 1f is a high performance underlay for pitched roofs, which must be ventilated in accordance with BS5250 2021. Install Protect 1F line with BS5534 2018. Protect 1f prevents the ingress of dust, rain and snow into the roof void. The membrane is classed as a secondary and should.