Delta Membrane - What is Broof(T4)
May 2025

What is Broof(T4)

BrooF(T4) is the highest fire performance rating of roof classification. Products with this rating will have been tested to ensure there will be no penetration of the roof system within 60 minutes. In addition, during the preliminary test, after withdrawal of the test flame, the selected specimens will burn for under 5 minutes, with a flame spread under 0.38 metres, across the area of burning.
BS EN 13501-5

Fire safety in building design has always been crucial, but after the Grenfell disaster in 2017, there’s now a greater focus on fire risks in flat roofs. The ‘Fire Safety-Approved Document B’ (AD B), introduced in 2019 and updated in 2020 and 2022. The document outlines requirements for roof construction to prevent fire spread, including building-to-building. A key update from previous versions, is the use of the European Classification system (BS EN 13501-5 ‘Fire classification of construction products and building elements – Classification using data from external fire exposure to roofs tests’) as the primary reference for external fire performance of roofs, replacing the National Classification system (BS 476-3:2004). BS EN 13501-5 outlines the fire performance classification for roofs and roof coverings against external fire. It uses four test methods from CEN/TS 1187:2012 and relevant extended application rules.

The four test methods to measure a roof’s fire resistance: t1 for Germany, t2 for Scandinavia, t3 for France, and t4 for the UK and Ireland. These tests assess fire penetration and spread, for example, from a burning tree branch. The highest rating, Broof(T4), means ‘Unrestricted and can be used anywhere on the roof,’ while the lowest rating is FRoof(T4).
Compliance

To comply with Building Regulations for fire safety in roof applications, the entire installed system must possess a valid test certificate. This means components, from membranes to surface materials, cannot be substituted with those offering different properties. For example, replacing an ‘E’ euroclass rating membrane with an ‘F’ rated membrane may jeopardize meeting fire certification requirements. Building Fire Regulations vary by area (heights). For example, Building Fire Regulations differ from roofs to balconies. Roof systems are rated (tested) as a complete build up, which will not rely on the rating of an individual component/product. Balconies in contrast are rated (tested) on an individual component/product. A component for a balcony must be “A” rated.

Building Regulations also clearly classify balconies, roof terraces and roofs. Balconies are considered “raised platforms” and are classified as ‘Specified Attachments’ attached to an external wall.

NHBC and BS 8579 further differentiate roof terraces and balconies: attached balconies are not habited or conditioned spaces and are usually bolted or cantilevered from the wall, including most inset balconies.

Approved Document B classifies roof terraces differently from balconies, resulting in different fire rating requirements.
Simplifying Product Selection

Delta’s field Technical Teams are equipped to offer valuable assistance on roofs, balconies and terraces, to help you select the most fitting roofing/waterproofing system for your project needs.

For all your project requirements, Delta’s Technical Team is a dependable resource. Offering expert advice, comprehensive support, and timely practical assistance. Reach us at 01992 523 523 or drop us an email at info@deltamembranes.com.