British Standards Document
BS EN 771-4
Specification for masonry units. Autoclaved aerated concrete masonry units

https://doi.org/10.3403/30203901U

BS EN 771-4 is maintained by B/519/1. The current release of this standard is:

BS EN 771-4:2011+A1:2015 Specification for masonry units. Autoclaved aerated concrete masonry units

https://doi.org/10.3403/30203901 (published 31/10/2011)

This standard is available from the following sources:

Other historical versions of this standard document also exist:

BS EN 771-4:2011 [current until 31/03/2016]
BS EN 771-4:2003 [current until 31/10/2011]
BS EN 771-4:2001 [current until 30/10/2003]