Advantages

• Cold & Warm roof application
  

• BBA Certified

• 3 layer spun-bonded membrane

• Clean and easy to use

• High performance & flexibility

• Excellent tensile strength

• No gusting wind noise

• UV stable for up to 3 months

• Excellent nail tear resistance

BS5534:2018 Wind Uplift
Each individual Vent3® underlay product has the batten gauge & zonal application for wind uplift printed on this packaging. The manufacturers declared values are available from the Cromar website. The Vent3® underlays may be used at any batten gauge in all wind zones when laid over nominally air-tight sheet sarking for example OSB, plywood, chipboard and insulation for warm-roof design. They may also be used in applications where slates are nailed directly onto sarking boards. Sarking boards, such as square-edged butt jointed planks, are not considered to be air-tight and the underlay is treated as unsupported.

Zone suitability applies only for underlays in applications where a well-sealed ceiling is present, ridge height is not greater than 15 m, roof pitch is between 12.5° and 75°, site altitude is not greater than 100 m, and no significant site topography is present. Other applications might require underlays with greater wind uplift resistance and it is advisable to seek professional advice. Zones 3 and 4 apply to Northern Ireland.