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Door & Window Security [Hardfacts]


Theft is a risk facing nearly all premises, and a suitable level of physical security should therefore be provided to all accessible external doors and windows.

There are many different forms of locks and related British, European and other security test standards, with ‘Hardfacts’ 3018: Locks and Lock Standards providing further information. This Hardfacts therefore provides some general advice on door and window security at typical commercial and domestic premises.

Risk Assessment
Criminals usually look for the easiest way into premises. With this in mind the general aim should be to provide all doors and windows with a comparable level of physical security, but with variations made having regard to various risk factors, for example:

  • What is behind or close to each door or window, i.e. what theft attractive goods are present/where are they kept?
  •  The degree of accessibility and possible concealment for criminals.
    (Note. Accessible doors and windows should be regarded as those that could be reached by an intruder standing on adjacent ground or an external staircase; or that could readily be reached by climbing, e.g. via adjacent single storey roof areas, bay windows, porches, pediments, adjacent soil/drainage pipes, walls or trees, etc.)
  •  Strength of construction of the building in comparison to any doors/windows.
  •  The nature of any manned guarding or other human presence on site.
  •  The nature of any electronic security, i.e. intruder alarm/CCTV systems on site.

Door and Window Security - General
There are a number of factors that contribute to good door and window security, for example:

Doors/windows and frames should be in good condition, of good fit, well secured to the building structure and any gaps around the frames filled with mortar or frame sealant (to conceal the frame fixings).

Timber doors/windows should be of external grade- and for doors a min thickness of 44mm (1 ¾ "), noting that hardwood is generally stronger than softwood.
For PVCu or metal doors, especially if glazed, the manufacturer’s intended use should be observed.
Weaker doors/windows, or specific areas of them, can be improved by adding secondary steel sheet facings/linings, or steel bars, grilles or mesh.

Door Hanging
Inward opening doors are less resistant to being kicked/barged open than outward opening ones, but can be improved by fitting a second lock, internal bolts or drop in braces.
Outward opening doors are more resistant to being kicked/barged open, as attack force is dissipated into the frame. However, such doors (and windows) can be vulnerable to attacks on their exposed hinges, so make them more resistant to attack by fitting hinge bolts.  

Any glazing needs to be well secured i.e. no loose or perished putty/beading. If any glazing is toughened glass (despite its name, a safety not security glass) security can be improved, and still meet safety requirements, by replacing it with laminated glass. ‘Hardfacts’ 3006: Security Glazing and ‘Hardfacts’ 5024: Glazing in the Workplace provide further information.

Procedural Security
The effectiveness of any security measure is always dependant upon proper use, so:

  •  All doors and windows should be adequately secured whenever premises are left unattended, and in homes when the occupants retire to bed at night. (Keep keys close at hand in case emergency exit is required).
  •  Don’t leave spare keys under mats, etc.
  •  Don’t label keys with your address.
  •  Where premises are open to the public, don’t leave unlocked padlocks or keys to doors/windows in their locks or otherwise unattended - they may be stolen   and (if their loss hasn’t prevented full locking up) later used to gain entry.
  • After locking up, don’t leave keys in locks or within sight or reach of glazing.

Insurer’s Minimum Security Standards
When insurance is sought against theft, its provision may be conditional upon premises having a certain level of physical security, often termed ‘Minimum Security Standard’ (MSS), or maybe Minimum Security Requirement or Condition.

MSS tend to concentrate on the fitting and use of common locks on typical doors and windows and may vary according to the insurer, type of property, e.g. domestic or commercial, or the type of insurance contract. The RISCAuthority, the UK insurer’s technical body has published a useful guide on the subject of MSS at homes - see Sources of Further Information.

Door Security - Locking
Locks typically used on doors vary according to the door type and use. Detailed advice on locks and related standards can be found in the aforementioned RISCAuthority guidance (aimed at homes but much of it of general application), but some general advice follows:

Hinged single leaf doors
These are usually locked as follows:

  • Timber doors - a 5 lever mortice deadlock with boxed striking plate, or rim cylinder deadlock, in either case ideally one certified as meeting one of the Standards in the BS x621 series. Note. Treat ‘stable type’ doors as two separate doors.                                                  
  • Metal frame doors - a 5 pin cylinder operated mortice swing (MS) lock. Ideally one certified as meeting BSEN 12209, with the cylinder meeting BS 1303 or TS 007 at the 3 Star level.
    Note. Security can be further improved by fitting a reinforced striking plate in the hollow frame and a cylinder ‘rose’- to prevent a wrench being used to grip and twist the (usually protruding) lock cylinder and snap it off.                    
  • PVCu doors - a 5 pin cylinder securing a system of moving boltwork having at least 3 locking points. Ideally one certified as meeting one of the Standards in the PAS x621 series, or otherwise at least having a cylinder that meets BS 1303 or TS 007 at the 3 Star level.                               
  • All Types – by means of a padlock; but choose a type with a closed shackle securing a heavy-duty padbar with externally non-removable fixings, and with the padlock ideally certified to a recognised standard, e.g. BSEN 12320 at Grade 4 or above or a Sold Secure tested equivalent.

Hinged double doors
These are usually adequately secured by:

  •  The 1st leaf being secured at top and bottom by rebate bolts, key operated mortice rack bolts or surface mounted key lockable bolts.
  •  The 2nd leaf locked as per a hinged single leaf door, or both doors secured together by a padlock as per the information in 'All Types' above.   

Sliding doors
These are usually locked by either a mortice or cylinder ‘hook’ or ‘claw’ lock, cylinder lock and moving bolts or a padlock - all ideally meeting a relevant standard outlined above. Patio style doors should have an anti lift device in the top rail and may benefit from a key operated patio door lock at the base of the centre rail.

Roller shutter/panel doors
These are usually locked by padlocking the internal operating chain in place, or fitting cylinder lock pin bolts through the side runners.
Any wicket gate should be treated as a hinged single leaf door.

Doors not used for entry/exit purposes
Unless used as emergency exit doors, see below, these doors should be locked as above or by lesser locks supplemented by internal bolts (key lockable if adjacent to any glazing), by padlocks or by drop in braces, etc.

Emergency exit doors
These doors are often relatively weak but, subject to strict controls to ensure unlocking at all times when the premises are in use, extra visible security devices, e.g. bolts, or secondary protection may be appropriate. If in doubt seek advice from the fire brigade or your insurers, and always record any such measures in your fire risk assessment.

Note. Detailed advice on this topic is available in a document called 'Security of emergency exit doors in non residential premises' which is available as a free download from The RISCAuthority website.

Detailed advice on this topic is available in a document called ‘Security of emergency exit doors in non residential premises’, which is available as a free download from The RISCAuthority website.

Window Security - Locking     
All accessible opening windows should be fitted with key lockable handles or separate window locks. Larger windows, i.e. those with  an opening edge greater than 1.2 metres length can be improved by fitting a second lock. Windows not required to open may be screwed shut.

Secondary Door/Window Protection
Where existing doors or windows cannot be readily improved/replaced, the fitting of a secondary barrier may be appropriate, for example:

Consider internal or external lockable steel bar/mesh gates, roller shutters, or internal collapsible (folding) steel grilles.

Consider internal or external steel bars, fixed or removable steel mesh grilles, roller shutters, or internal collapsible (folding) or roller grilles.

Secondary barriers should ideally be certified as meeting a recognised security standard, e.g. a suitable security level of the Loss Prevention Certification Board’s LPS 1175 scheme.

Key Action Steps

  • Review current physical security at your premises, including any outbuildings.
  • Check whether any insurer MSS applies; and if so that you do comply, or that you have their agreement for any alternative arrangements.
  • Seek independent crime prevention advice, e.g. from the police.
  • Source doors/windows or security devices from competent suppliers/locksmiths, e.g. respectively, a member of the Glass and Glazing Federation (GGF) or   Master Locksmiths Association (MLA).
  • Review security in the event of any loss. If you do not do so are at high risk of a repeat incident

Sources of Further Information

Other ‘Hardfacts' in the Property Protection - Security series, which are available in our ‘Knowledge Store' at

Your local police Crime Prevention Unit

Your insurance broker or insurance company 

The Glass & Glazing Federation Tel 0870 042 4255 or see

Master Locksmiths Association (MLA). Tel 01327 262255 or visit

The Door and Hardware Federation (DHF) Tel 01827 52337 or visit

The RISCAuthority (the UK insurers' technical advice body) see

In particular see:-




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Please Note
This document contains general information and guidance and is not and should not be relied on as specific advice. The document may not cover every risk, exposure or hazard that may arise and Aviva recommend that you obtain specific advice relevant to the circumstances. AVIVA accepts no responsibility or liability towards any person who may rely upon this document.

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