Double Glazing Accreditations Explained

In last month’s blog we spoke about accreditations and the importance of selecting a firm with a full suite of them.  But what do they actually mean and which ones do you need to look out for?


One of the most well-known accreditations is Certass.  Certass Limited is, brace yourselves, a UKAS approved certification body for the operation of a competent person scheme under a department of communities and local government (DCLG) license and a green deal certification body under licence from the Department for Energy and Climate Change (DECC).


Membership of Certass is not automatic, firms have to be financially and technically assessed to ensure they meet required standards.  When you see a Certass logo on a double glazing firm’s website, it should give you peace of mind that the organisation is reputable and will be regularly re-assessed by the governing body for quality.  So watch out for it on websites or search their database to find a firm.

Next up is TrustMark.  Again, backed by the government, TrustMark is an easy to use website to find local tradespeople who are trustworthy, reliable and operating to government endorsed standards.  If a firm is TrustMark registered, it works to a code of practice set down by an approved scheme operator.  For double glazing this includes:

  • A firm’s technical skills have been independently checked through regular on-site inspections, as well as checks on their trading record and financial status
  • Firms have signed up to a code of practice that includes insurance, good health and safety practices and customer care
  • Firms will be able to tell you about any building regulations you must comply with and may also be able to provide appropriate certificates
  • If you have a problem or disagreement with the firm, there will be a clear and user-friendly complaints procedure to help resolve the issue

So you will know you’ll be in safe hands.

G&L Windows are both Certass and TrustMark accredited.  We are more than happy to talk through which governing bodies we work with and how this ensures the quality of our work – just contact us and we’ll be happy to help.

You can also follow some ‘real-time’ installations by following us on Facebook.  We regularly post photos of our most recent jobs to show the quality of our work – just search for G&L Windows Ltd.