Thatch Fire Membrane System 

The Thatch Fire Membrane System is designed to meet the specifications as recommended by Building Control for both spread of flame, penetration and thermal insulation values.

Please note that this system is not recommended as part of ‘The Dorset Model’ for new build projects and extensions where the property is 12m or less from the boundary. If your project meets these criteria, please look at our Thatch Fire Board System.     

The system consists of:

• Thatchbatt® ‘top hat brackets’ (50mm Slabs only) 
• Thatchbatt® Slabs
• Thatch Firewall Membrane

System overview:

The Thatch Firewall Membrane will offer a 60 minute fire barrier in accordance with BS476 Part 3 classification EXT.S.AC. With the added benefit of being a flexible, water resistant and breathable product.

The Thatchbatts® are designed to sit on the ‘top hat brackets’ between the roof rafters to meet the required insulation levels. Thatchbatts® are non-combustible, semi-rigid, high quality resin bonded mineral rock slabs. These are therefore ideally suited for use within the construction of a thatched roof because they offer zero spread of flame and good thermal transfer properties.       

Although the Thatchbatts® have been designed to be semi-rigid, the ‘top hat brackets’ are only required for the 50mm Thatchbatts® to ensure that the top surface of the slabs are level with the top edge of the roof rafters. Due to the additional thickness of the 100mm Thatchbatts®, brackets are not normally used.

Due to the flexibility of this system it is favoured for existing properties that are not able to accommodate the rigid Thatch Fire Board System.

Application:

1.   Six ‘top hat brackets’ are required for each Thatchbatt® Slab; these are nailed to the top of the roof rafters using galvanized nails. 

2.   Thatchbatts® are then positioned between the rafters and will sit on the ‘top hat brackets’. If 100mm are required then top hat brackets are not normally needed.

3.   Thatch Fire Wall Membrane is then fitted directly on top of the roof rafters. The membrane is fitted horizontally with a minimum overlap of 75mm at each point the membrane joins.

The membrane can either be stapled or nailed to the roof rafters to hold it in place on a temporary basis until the battens are fitted.

4.   25mm x 50mm battens are then fitted horizontally over the top of the Thatch Fire Wall Membrane at 300mm centres, with the first batten 125mm from the arris rail. Please note: if the Thatcher is going to use crooks, the size of the battens may need to be increased.

The components within the Thatch Fire Membrane System contribute to a part of the overall roof construction. Therefore please consult with your Architect with regard to the performance of the complete roof structure, to include requirements for other components such as vapour barriers etc.

Additional information for both Thatch Fire Wall Membrane and Thatchbatts® is available from the main menu of our website.

Test certificates are also available upon request.