Protect VP400 plus LR is a highly vapour permeable roof underlay. It offers the lowest vapour resistance of any Type LR roofing underlay in its class, and yet it remains completely airtight. It is suitable for use in all pitched roofs. Please note this product does not require the joints & laps to be taped but must be battened correctly. PropertiesLength: 50m. Width: 1m. Roll size: 50m2. Roll weight: 9.68kg. Weight: 170gsm. Brand: Protect. Certification: CE marked. Protect VP400 Plus LR As the air tightness of buildings and dwellings continues to improve due to better workmanship and new practices, it is ill advised to allow uncontrolled air movement within the structure, including through a roof underlay in roofs with no vapour control or air barrier layers. One of the primary functions of roof underlays is to help manage the wind load pressures on the roof. In order to achieve this the underlay should have sufficient mechanical properties to be able to deflect the wind load pressures safely over the structure, one essential other property is that the underlay be water and air tight. Air leaky or air permeable underlays allow air to penetrate the membrane making it much more difficult to withstand the maximum wind load pressures and driving rain without other surface treatments. Features Highly vapour permeable, but completely airtight.* Completely watertight >7.0m water resistance. Strongest underlay in its class/weight range. UV and heat resistant. Tough and durable. Can be used as temporary roof covering. Has unrestricted use for wind uplift in all exposure conditions in the UK and Ireland. Suitable for zones 1-5 at 345mm batten gauge. Helps to avoid condensation risk in the roof space in accordance with BS 5250 and NHBC requirements.