Approved Document B is published in two volumes. Volume 1 covers dwellings; Volume 2 covers other buildings. Both were updated in 2022 following post-Grenfell review.
Volume 1 Section 3 sets out that concealed cavities must not undermine compartment lines. Section 9 adds requirements for external wall cavities: limited combustibility materials are required in buildings over 11 metres, and A2-s1,d0 or better classification in buildings over 18 metres. These classifications apply to every product installed within the external wall cavity, including cavity barriers.
Volume 2 Sections 8 and 9 repeat these requirements for non-residential buildings, with additional requirements for taller buildings. Both volumes require cavity barriers to be placed at compartment boundaries, at floor and party-wall junctions, around openings in external wall cavities, and at the edges of cavities. Correct positioning at each of these locations is essential to maintaining the integrity of the compartment line.
ADB Volume 1, Table 9.1 and Diagram 9.1 map directly to Tenmat products: the NVFB range (A1 stone mineral wool) and the VFB open state range (A2-s1,d0 or better classification).