Thatch Firewall Membrane

Thatch Firewall Membrane is ideally used in conjunction with Thatchbatts® as part of our comprehensive Thatch Firewall Membrane System. An ideal flexible fire barrier for older properties especially if the roof timbers are old and uneven.

Coverage – Each roll covers an area approximately 46.5m² to include the required overlaps

Product Description

Manufactured in the UK, the Thatch Firewall Barrier is a flexible fiberglass woven fabric, coated on both faces with a temperature resistant inorganic aluminised polymer system.

Thatch Firewall Barrier is more commonly used on an existing thatched roof when the timbers are not able to take the rigid TAS100 Thatch Fireboard.

Firewall is classified as Water Vapour and Air Permeable, this coupled with its good tensile strength makes it an ideal fire barrier for thatched roofs.

To create a comprehensive fire barrier and to achieve BS476: Part 3: 2004 and CEN/TS 1187: 2012, test 4, it should be used with a minimum 50mm thick Thatchbatt® and our wired fixing system.


  • Roll Length: 50m
  • Roll Width: 1m
  • Roll Weight: 26 kg
  • Area Weight: 450g/m²
  • Thickness: 0.40mm


  • Easy Application
  • *Water Resistant
  • Air & Water Vapour Permeable
  • Strong and Durable
  • Flexible

*This product should not be used as a replacement for a waterproof membrane or roofing felt.


  • BS476: Part 6: 1989 + A1: 2009 – Fire Propagation
  • BS476: Part 7: 1997 – Surface Spread of Flame
  • Class 0 Summary Report
  • *BS476: Part 3: 2004 – Classification and method of test for external fire exposure to roofs
  • *CEN/TS 1187:2012, test 4 – Test method for external fire exposure to roofs
  • *EN 13501-5:2005 – Classification report for external fire exposure to roofs
  • Water Vapour Permeability Test (In accordance with BS7209: 1990)
  • Air Permeability Determination Test
  • Classed as “Showerproof” when tested in accordance with BS5066 WIRA Shower Test

*These test reports are based on a combined test using a minimum 50mm Thatchbatt®.


To achieve both integrity and insulation, Thatch Firewall Membrane needs to be used in conjunction with Thatchbatts® to create a more comprehensive thatch fire barrier and increase thermal insulation values. As already mentioned you will also need to follow our Thatch Firewall Membrane System to meet the requirements of BS476: Part 3: 2004 & CEN/TS 1187:2012, test 4. Find out more about the Thatch Firewall Membrane System.


Starting at the eaves Thatch Firewall Membrane is laid horizontally across roof timbers that are normally set at approximately 400mm centres, with a minimum 75mm overlap required on all joints. The Thatch Firewall Membrane can either be stapled or nailed to the rafters and then battens are fitted over the top with 300mm centres, with the first batten 125mm from the arris rail.

If required, TAS Fire Silicone can be applied between the membranes at the point that theyjoin. For best results; apply a 5mm diameter bead of silicone using a wave effect pattern within the 75mm overlap point. Although the TAS Fire Silicone will have some instant grip, it will require 24 hours to fully cure. For best results, please ensure that the surface is clean and dry and not exposed to frost during the curing process.

Product Note

Fabrics contain no asbestos, RCF’s or respirable fibres. No organic solvents used in manufacture all coatings are water based. MSDS available on request.

General Notes

Please consult your architect or building control officer with regard to the required insulation values and the need for a vapour control layer (VCL).

  • Thatch Firewall Membrane is available exclusively through Thatching Advisory Services.
  • To reduce the risk of damage, each roll is individually packaged in a strong cardboard carton
  • Individual rolls can be sent out via a courier and multiple rolls will be euro strapped onto a pallet and sent out via our pallet distribution provider.
  • All products are supplied with Installation Instructions, which will need reviewing before completing any works.

COSHH & MSDS documents are available upon request

For more information on this and other Thatch Fire Protection Products and Systems, please contact us.

Development Code Notes

Many years ago PU28 was used as a development code for a new membrane product. This code has stuck with many fire membranes to this day and is widely used to describe fire barriers in the thatching industry.

The term PU28 Fire Barrier or PU28 Thatch Fire Membrane has become generic and is therefore is no longer exclusive to one product or one company.

Due to the comprehensive suite of testing and our long standing in the thatching industry, all our membranes continue to be sold using the name Thatch Firewall Membrane.

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