26. March 2021

Cembrit Windstopper Extreme 

BBA Certificate 21/5885

Cembrit is pleased to announce that it we have received another approval from the British Board of Agrément (BBA) for our building baord range Windstopper Extreme, providing peace of mind to specifiers who choose to use Cembrit’s non-combustible fibre cement sheathing boards on their projects.



What is certified?

This Agrément Certificate Product Sheet(1) relates to Windstopper Extreme, fibre-cement boards for use externally as sheathing boards to new and existing buildings, providing temporary weather protection prior to over-cladding with a permanent façade rainscreen cladding. The boards can be used structurally when applied to steel-frame substrate walls. The boards are non-structural when applied to timber-frame substrate walls, providing racking resistance where required.


Why the BBA?

The British Board of Agrément is one of the UK’s leading notified bodies offering approval, certification and test services to manufacturers of products and systems supplying the construction industry. BBA approval is recognised by building control, government departments, architects, local authorities, specifiers, and industry insurers like the National House Builders Council (NHBC). Independent confirmation that the products covered by a BBA certificate are fit for purpose is a significant advantage for specifiers. The certification ensures peace-of-mind that BBA 3rd party approved products match the required specification. and comply with Building Regulations and the recommendations of other approved bodies, such as the NHBC.

Certification Includes

• factors relating to compliance with Building Regulations where applicable

• factors relating to additional non-regulatory information where applicable

• independently verified technical specification

• assessment criteria and technical investigations

• design considerations

• installation guidance

• regular surveillance of production


• formal three-yearly review.


For further information email info(at)cembrit.co.uk or tel: +44 (0) 208 320 1184.

Cembrit Windstopper Extreme

KEY FACTORS ASSESSED Strength and stability — when used as sheathing boards, the boards will contribute to the racking resistance of walls.   Performance in relation to fire — the boards have a reaction to fire classification of A2-s1, d0 to BS EN 13501-1 : 2018 Resistance to moisture — the boards have adequate moisture resistance. Durability — provided that all joints between the boards are sealed and fixings are finished flush to the surface of the boards, Windstopper Extreme boards may be exposed for up to 12 months under normal periods and conditions of wind, rain, and heat exposure, prior to the rainscreen cladding finish being installed.