The accepted practice for strongroom construction by the leading British companies is that the wall thickness should be three times that
of the actual protective thickness of that of the door blade. i.e. Chubb 3.5 AA, Tann 450 FTS, matched to a 12" wall either pre-cast or
cast-in-situ. (pre-cast allows for better quality control of the mix but cannot provide watertight construction).

It will not be surprising to learn that the 2 meter figure mentioned includes the foundation structure against which the concrete was poured.

The highest security vaults in this country such as the Cash Centres of our leading banks are approximately three feet thick to accommodate doors with a protective thickness of 10 to 12 inches.

In most cases they are surrounded by a visual inspection corridor of such width that precludes the use of the packed lance and heavy core drills.

The design of security concrete has greatly improved over recent years as have the quality contols applied over its placement.

This method of breaching a strong room wall is now incorporated into the Standards of the VdS Grades CD.