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In essence this is your guarantee that the windows you are purchasing have been checked by an independent third party as being ‘fit for purpose’ and secure when tested against PAS 24 and the relevant material standards as shown below.  It is also important to know that the tests are conducted on the whole window and not individual component parts.  As an old colleague of mine used to say “It’s a bit like a car crash test.  The whole car is crashed into the barrier, not just the wheels or the rear indicator light”.

PAS 24, like most British Standards, is a minimum standard.  In other words it doesn’t include higher or lower grades for security and so windows that are tested to the specifications of the standard either pass or fail.  Although some of the windows that pass will be a little stronger than the minimum required, a minimum standard encourages engineers to design the window to pass at the minimum requirements.  This makes economic and environmental sense and the effectiveness of windows certificated to this standard has proven that the minimum levels set by the British Standards were just about spot on.

The process of testing and certification

What actually happens is this:   The manufacturer or ‘fabricator’ (the term used in the industry for companies that make aluminium and U-PVC windows) submits a range of windows to a UKAS accredited test house for testing to PAS 24 and the relevant performance standards.  Having achieved passes on these windows the factory and the manufacturing process are examined by a UKAS accredited Certification Body.  Providing the independent certification body is satisfied with the manufacturing facility and the way in which it is managed they will award a certificate to the manufacturer, which will enable them to market their windows as ‘certificated’ to PAS 24 and the material based performance standards. 

Test Houses and their UKAS accreditations

LINK: Assa Abloy Test Laboratory

Schedule of UKAS accreditation

LINK: British Board of  Agrément (BBA)

Schedule of UKAS accreditation

LINK:  BSI (British Standards Institute )

Schedule of UKAS accreditation  

LINK:  LPCB (Loss Prevention Certification Board)

Schedule of UKAS accreditation

LINK:  Chiltern Dynamics Ltd

Schedule of UKAS accreditation

LINK:  Exova Warrington apt (Certisecure)

Schedule of UKAS accreditation

LINK:  MILA Testing

Schedule of UKAS accreditation  

LINK:  Fullex Testing Services

Schedule of UKAS accreditation

LINK:  Winkhaus Laboratories

Schedule of UKAS accreditation

LINK:  Wintech Engineering Limited

Schedule of UKAS accreditation

To ensure that the quality of manufacture is maintained, the Certification Body will regularly visit the production facility and periodically re-test the products to make sure that they are still performing to the standards.    If the manufacturer changes a component part of the window they are obliged to inform the Certification Body who might require a re-test.  The PAS 24 tests are numerous to say the least but in essence include tests that represent the forces that could be applied by the burglar, such as levering the frame and trying to prize out the sealed unit.  Because these tests are conducted under strict laboratory conditions, where the tester has an opportunity to inspect the window beforehand, it is reasonable to assume that the window’s performance is likely to better out in the field.   The performance tests include water and wind resistance, to make sure they don’t leak or let the draughts in.    

Fit for purpose’ standards for windows

BS 4873: 2009 Aluminium alloy windows and doorsets. Specification

BS 644: 2009  Timber windows. Fully finished factory-assembled windows of various types. Specification

BS 6510: 2005 Steel-framed windows and glazed doors  

BS 7412: 2007 Specification for windows and doorsets made from unplasticized polyvinyl chloride (PVC-U) extruded hollow profiles

BS EN 12608:2003 Unplasticized polyvinylchloride (PVC-U) profiles for the fabrication of windows and doors. Classification, requirements and test methods

BS 6375-1: 2009 Performance of windows and doors.  Classification for weathertightness and guidance on selection and specification

BS 6375-2: 2009  Performance of windows and doors.  Classification for operation and strength characteristics and guidance on selection and specification

BS 6375-3: 2009 Performance of windows and doors.  Classification for additional performance characteristics and guidance on selection and specification     

Getting windows up to and maintaining this standard represents an enormous investment by the manufacturer and it is hoped that should you wish to change your windows you will make sure that the vulnerable windows are replaced with those that are certificated to PAS 24:2012.  It is quite possible that the company you use to replace your windows doesn’t actually make them, in other words they are installers only.  In this case make sure that they know that they are to supply certificated windows and ask for proof.

Laminated glass

PAS 24 windows are normally fitted with sealed units using two sheets of toughened glass.  If you live in an area that has an average or higher than average level of burglary you should specify the use of 6.4mm laminated glass on the inner pane of the sealed unit.  Laminated glass is more difficult to break through than toughened (which can be broken easily with a sharp implement) and this will buy you valuable seconds, during which time a neighbour may hear what's going on and call the police. For more information about glazing see Glazing for domestic security .

How can I check the certification? 

It is important to understand that manufacturers of PVC-U and aluminium windows buy the profiles that make up the windows from profile manufacturers.  The majority of them then produce the windows by following a specification laid down by the profile company.  Although the majority of profile companies don’t actually manufacture windows they will make up a range of windows and have them tested and often certificated also.  Therefore a manufacturer will sometimes provide you with the certification documents obtained from and by the profile company and you’ll discover that the actual window fabricator has not had them tested in their own name.   So don’t get fobbed off with documentation from a window company that shows a different company name on the certificate.  However, if you buy your windows from an installer then they will have to provide you with the manufacturer’s documentation and that’s fine.  You can see then that it is the manufacturer of the window that has to hold the relevant documentation. 

So, before you sign anything or pay any money over require, as part of your agreement with the company, that they produce to you a certification document that covers the windows that you want to purchase.  A professional company will have this information to hand and will have no problem in furnishing you with the necessary documents.   In some cases a window installer will have to source his windows from a different supplier than he normally uses to satisfy your requirements for a certificated window.

To help you check the paperwork here is a table listing the details and contact telephone numbers of the certification bodies that are able to certificate windows to PAS 24.  You can check if a manufacturer is certificated to produce PAS 24 windows by carrying out a search using the links provided

Certification Bodies

LINK: BM Trada Certification

01494 569700

This organisation issues a ‘Q Mark’ certificate for doorsets that are certificated to the security and performance standards

Online checks can be made at this link

LINK: British Board of  Agrément (BBA)

01923 665300

This organisation issues a BBA certificate for doorsets that are certificated to the security and performance standards. The certificate is reproduced in full on their website

Online checks can be made at this link

LINK: BSI (British Standards Institute)

08450 765600

This organisation issues a ‘kitemark’ certificate for doorsets that are certificated to the security and performance standards

Online checks can be made at this link

LINK: Exova Warrington apt (Certisecure)

0161 787 3291

This organisation issues a ‘Certisecure’ certificate for doorsets that are certificated to the security and performance standards. The certificate is reproduced on their website

Online checks can be made at this link  

LINK: LPCB (Loss Prevention Certification Board)

01923 664100

The LPCB is part of the Building Research Establishment.  This organisation issues an LPCB certificate for doorsets that are certificated to the security and performance standards

Online checks can be made at this link

What do certification documents look like?

Over the next few weeks I will be contacting the certification bodies to see if I can obtain examples of their documentation so you know what to look for.  BBA certificates (See above) are reproduced on line anyway. 

What’s the difference between testing and certification?


When a window manufacturer wants their windows to be good enough to pass the security and fit for purpose standards they will submit a range of samples to a UKAS accredited test house.  If the windows pass the tests it can be said that those window samples met (in some cases exceeded) the standards.  However, testing is no different from having an ‘MOT’ conducted on your car.  All the MOT test certificate proves is that on the time and day the tests were conducted the vehicle passed.  The next day the exhaust might blow or a headlamp might stop working.


To ensure that the windows that passed all the original tests are made in the same way into the future a window manufacturer forms a relationship with a certification body who will carry out regular and detailed inspections of the factory to ensure that the manufacturing processes are consistent.  The certification body will also periodically re-test window samples just to make sure that they are as good as the ones that initially passed the tests.

Who is UKAS?

The United Kingdom Accreditation Service is the sole national accreditation body recognised by government to assess (against internationally agreed standards) organisations that provide certification, testing, inspection and calibration services.  Accreditation by UKAS demonstrates the competence, impartiality and performance capability of these evaluators.  

Where can I buy these certificated windows?

The adverts that appear in this section of Window security have been checked against the certification websites so that I know and you know that they make or can supply the general public with windows that meet the security and performance standards.   

The next thing you can do is carry out internet searches and then check the manufacturers’ claims using the information I have given you.  Bear in mind that many of the window manufacturers that have gained certification do not supply the general public, or if they do, they will supply window installation companies and or private builders.  Some window installers and manufacturers who supply the public advertise on the police Secured by Design website, but unfortunately there’s no information to tell you what markets they supply.  Secured by Design is all about designing out crime opportunity in new building developments and so the majority of companies listed by SBD supply windows to builders and major developments and not to individual householders. 

Secondary glazing  

Secondary glazing can be defined as the installation of a fully independent window frame on the inside of an existing window.  If you live in a building that has planning restrictions that prevent you from replacing the existing widows (which might be insecure, such as traditional leaded lights), the installation of a secondary glazing system that is certificated to PAS 24 might be the solution for you.  (See Security for existing windows, Secondary glazing )