Common security weak spots in a building include the partitions, cavities and ceilings. Peter Caplehorn considers how specifiers can reinforce elements so they are less vulnerable to attack
Security is now an issue all specifiers should bear in mind, even if the client expresses little or no interest in this area of the brief. This is because today’s buildings are so complex threats to the occupants or the building can come from many quarters. These threats can be a risk to health and safety and can also be an economic issue.
Ensuring areas in a building are separated is important – for instance, it is essential to ensure airside and landside in an airport are kept separate at all times. Detailing of boundaries between these different areas of security can be complex. Emphasis is normally given to the high-profile areas – however, it is important to ensure the entire separating line is considered.
Normal stud walling or block work is open to attack although it may appear solid.
Stud partitions should be specified to be continuous from the soffit to the structural floor finish. Ensure the partition framing elements are at least twice the depth normally required. Fixings at the top and base should also be specified to be twice as close to each other than usual.
Depending on the level of security required the coverings can be enhanced in a number of ways. Plasterboard can be replaced by a cement composite as these are much harder and used in areas of high wear. Additional strength can be achieved by adding steel mesh on either side of the studs behind the finish. This must be fixed by a continuous steel strip top and bottom to the structure. Joints in the mesh must be over lapped and preferably stitched together with wire.
For more secure specifications, the whole wall can be lined with steel plate within the partition build-up. The thickness of the steel determines the robustness. Joints and fixing must use one-way screws or be welded. If a substantial amount of steel is used, ensure it is corrosion-protected as rusting over time could cause it to fail.
Masonry walls can be used – however, unless very substantial, these are quite vulnerable. Block walls up to 100 mm thick are easy to break through, especially if made from lightweight blocks. If masonry is required this can be enhanced using reinforcement in the mortar bed. For greater resilience reinforcement, rods can be run vertically through blocks with hollow centres and the cavity then filled with concrete. Retention channels should be used either side and top and bottom to ensure adequate bond with the structure.
Consider the complete line of security required through all cavities and sections. Grilles and barriers of equal robustness will be required at every point. Also ensure where the detailing changes fixing used are well anchored back to the structure.
Any opening or service ducts or easily removed decorative finishes should be specified with one way screws, high-quality adhesive or welded, making any element virtually impossible to remove.
Underfloor voids are often missed because they are considered too small. However any opening is a point of weakness. These can be used to lever a bigger hole in an otherwise robust barrier. Floor and ceiling fixtures and finishes should stop at the secure boundary leaving the enhanced wall to run through.
It has been known for any cavities and particularly ceilings to be used to store stolen goods. For some projects, therefore, the ceiling may need to be secure. In some cases it may be enough just to make casual lifting of tiles more difficult. Most suspended ceilings suppliers offer special retention fixings. For a more secure solution, the specifier should consider a solid build-up to the ceiling with a similar detail using mesh or steel plate as suggested for partitions.
5 Areas of special risk
Special risk areas should be subject to a separate risk assessment. Levels of security specified must match the risk. It is much cheaper to build in measures during construction than to add them later. Clear analysis during the detailed design stage
and perhaps the benefit of the advice of a security specialist may prove worthwhile.
- Advice is available from the Home Office
- Review with the client the degree of threat and security required
- Review the specification from its widest scope to the finest detail
- Look for weak points quite often fixings or services openings
- Consider the complete line that is required to be secure.
Subject guides similar to this are available from Barbour as part of its Construction Expert and Specification services. For further information, contact Barbour on 01344-899280 or visit www.barbour.info