VapR-free Xtra is a multi layer laminate film composite made of polyolefin materials, resulting in a pitched roof underlay that has high vapour permeability but is also highly water resistant.






Commercial and Domestic

VapR-free Xtra is suitable for both Commercial and Domestic buildings, it is the ideal roof underlay for Warm and Cold Pitched Roofs.

BBA Approval

VapR-free Xtra membrane has received BBA Approval and complies with BS5534-2014 Code of Practice for slating and tiling and NFRCTB6.

High performance breathable
roof underlay

zone map

Product Data

Roll Width
(linear m)
1.0 1.5
Roll Length
(linear m)
50 50
Coverage/roll/m² 50 75
Roll weight/kgs 6.1 9.15
Rolls/Pallet 56 63

Quality Assurance

BS5534: Anex A
Wind Uplift Resistance

Vapr-free has been approved by the BRE for use in:
Zones: 1-3 with 354mm Batten gauge
Battened lap Exceeds 1150
Zones: 1-5 with 250mm Batten gauge
Battened lap Exceeds 1600
Zones: 1-5 with 354mm Batten gauge
Taped lap Exceeds 1600
Zones: 1-5 with 354mm Batten gauge
Integrel Taped lap Exceeds 1600
(see zone map above)

Technical Data

Property Units Value
Weight g/m² 122
Water Vapour Resistance Sd (M) c.0.02
MN/sg 0.19
Water Vapour Transmission g/m²/24 hr 1065
Fire Rating - EN13501-1: 2010
Exposure Times UV Degradation - 3 months

Roof Space Ventilation

Prevention of Condensation
The complete roof construction, ceiling boards, underlay, insulation and roof tiles should be considered as a total roof system with regard to condensation risk, details of which can be found in our BBA certificate.
The risk of condensation is greatest during the first heating period when the moisture levels are high.

Roof Space Ventilation
The NHBC require that for all New Build Homes, ridge or high level ventilation is installed when a vapour permeable membrane such as VapR-free Xtra is used. We recommend the membrane should stop 5 to 30 mm from the apex of the roof and a ventilated dry ridge system be used to achieve the required level of ventilation.

VapR-free Xtra must be installed with the red printed side face- up and overlapped with the minimum dimensions listed. Trimming is achieved with a sharp knife. When partially supported with a horizontal lap between battens, an extra batten should be introduced 25 mm above the bottom edge. This will restrain the lap from opening under wind uplift.

Weather Tightness
VapR-free Xtra is highly water resistant and prevents the ingress of wind driven rain. It can be used as a temporary roof covering and left exposed to the elements, however this period should be kept to a minimum.