The Dorset Model and Building Regulations

Thatch-Safe and Building Regulations

The aim of Thatch-Safe® was to provide a one product solution for fire barrier and insulation requirements for new thatched buildings which also addressed:

1. Longevity of the thatched roof – should it not catch fire

Thatch-Safe®  is proven to be truly micro-porous so the roof can breathe. This maximises the lifespan of the thatched roof.

2. Heat transfer from chimney to thatch.

Thatch-Safe®  is designed to be wrapped around the chimney under the Thatch as a simple and cost effective solution to the No 1 known cause of Thatched roof fires.

Thatch-Safe and the Dorset Model

Thatch-Safe® has been developed to meet the same criteria as The Dorset Model ie B4 Building Regulations. Plus it has insulation – so that with 400mm of Water Reed it meets 0.2µ value, making it a one product solution for fire protection and heat loss prevention.

Regulation B4 requires that the roof of a building shall offer adequate resistance to the spread of fire over the roof and from one building to another, having regard to the use and position of the building.

Thatched buildings generally should be at least 12m from a boundary except that separating semi-detached houses. Small (3m2) thatched extensions may be as near as 6m to a boundary.


  • Rafters to be overdrawn with minimum 30 minute water-resisting fire barrier and
  • 50 x 25mm battens are recommended on a micro-porous sheet.

THATCH-SAFE® is not just designed for new thatched roofs. It is flexible so not limited to regularly shaped roofs, hence it is also used on older thatched properties whose roofs are more undulating- solid board application is very hard to maintain the integrity on undulating roofs where Thatch-Safe® benefits with no such difficulty in applications especially with eyebrow or dormer windows, valleys and non standard features of a roof.

For more details, please contact us today.