Easy Trim Master Breathable Roof Underlay Felt 112gsm 25mtr x 1mtr

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Easy Trim Master Breathable Roof Underlay Felt 112gsm 25mtr x 1mtr

The Easy Trim Master breathable roof underlay delivers performance and value for money, with a 3 layer spun bond based membrane that provides excellent performance whilst being lightweight and flexible.

The Easy-Trim Master 112gsm breather membrane is a vapour permeable and air tight breather membrane, suitable for Warm and Cold roof applications, and is designed for use in both fully supported and unsupported installations in tiled or slate pitch roofs.

The Master 112gsm breather membrane features a high vapour permeability, superior water resistant performance, and brilliant tensile tear strength.

Suitable for applications on warm, cold and hybrid roofs, together with Scottish sarking boards, and equally suitable for installations in timber and metal framed constructions.

Wind Zone Suitability

The wind uplift resistance figures for Easy-Trim breather membrane applies in the geographical wind zones stated below, where a well-sealed ceiling is present and the roof has a ridge height of ≤15m, a pitch between 15 degrees and 75 degrees, and a site altitude of ≤100m, and where the topography is not significant.

The required uplift resistance for other roofing projects should be determined using BS5534: 2014 +A1: 2015 and the declared wind up lift resistance which can be made available through the manufacturer's technical department.

  • ≤345mm batten gauge with batten lap: Zone 1 to 2
  • ≤250mm batten gauge with batten lap: Zones 1 to 5
  • ≤345mm batten gauge with taped lap: Zones 1 to 5


  • BBA certified for warm and cold roof applications BBA 10/4753
  • UV stable for 3 months
  • Type LR Underlay to BS5250
  • Vapour permeable


Installation Guide

All Easy-Trim breather membranes are suitable for installations on all major pitch roofing and timber frame applications, and must be installed in accordance with their fixing instructions, complying with the recommendations of BS5534: 2014 + A1: 2015; BS5250: 2011 and BS8000-0: 2014 and any other applicable standard.

These products are designed to be installed by competent and experienced installers of slates and tiles.

Install Easy-Trim breather membranes by rolling out the membrane horizontally across the rafters going from left to right, with a 100mm lap over the pre-installed felt support trays at the eaves (preferably taped with the double sided overlap tape). Ensure the membrane is installed with the printed side facing out.

Continue with the next row above that, maintaining the prescribed horizontal and vertical laps in the table below, over the lower membrane.

Horizontal laps in the underlay should be taped with double sided overlap tape, or battened over and where possible the lap of the underlay should coincide with closest tiling or slating batten.

Vertical laps should have a 100mm lap min and positioned above a rafter.

Ventilated Ridge: For ventilation at the ridge, the membrane should be stopped about 5 – 30mm from the apex of the roof, to achieve the recommended 5000mm/msq ventilation.

Non Ventilated Ridge: In this application ensure a 150mm overlap of the membrane across the apex of the roof on both sides, before installing a dry ridge kit.

Supported: All Easy-Trim breather membranes are suitable for use in fully supported applications. When fully supported on sarking sheathing, the products have adequate support to withstand wind uplift in all wind zones. Such applications include, installations over e.g. plywood, OSB boards and insulation for warm roof designs.

Unsupported: All Easy-Trim breather membranes are suitable for use within the geographical wind zones stated in table three of Easy Trim's BBA Cert. 10/4753.

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