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Is Your double glazing Installer Qualified?

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Nick Dardalis

We are often asked how to determine whether a double glazing installer is qualified or competent to do the work. So while we’ve written lots of buying guides to help customers find their perfect aluminium doors and windows we thought it was time to take a closer look at the installers.

What Qualifications does a double glazing installer need?

lady double glazing installer measuring an open white window

It is not easy for homeowners to easily understand the qualifications a double glazing window installer should have, but the process starts with Building Regulations.

Most residential window installations are covered by UK Building Regulations.  For self-certification of window installations, registrations with a competent person scheme like the Fenestration Self-Assessment Scheme (FENSA) are required, for which installers must meet certain entry criteria. FENSA is the best-known competent person scheme, CERTASS is the other. 

Minimal Technical Competencies, or MTC was introduced in September 2012 by the Department for Communities and Local Governments. Individual installers and door and window surveyors must be able to demonstrate that they have the ‘minimum technical competencies’ (MTCs) required to carry out correct window and door installations.  As a result, several card-based assessment schemes are designed to demonstrate MTC compliance. 

The minimum standard homeowners can expect is NVQ Level 2 for installers and NVQ Level 3 for surveyors. 

Since 2012 FENSA has operated MTCs, now mandatory for people surveying or installing windows and working for any fenestration-related business.  

Finding out about double glazing installer qualifications

The first step to being certain of a qualified and professional installation is to speak to a window company. All professional window companies will not hesitate to demonstrate their staff’s qualifications.

For homeowners wishing to contact organisations directly to learn more about fenestration-related qualifications, FENSA, CERTASS, and GQA Qualifications are the most suitable.  FENSA and CERTASS have consumer-friendly websites to get more information. GQA Qualifications in particular now offers over thirty different types of relevant qualifications for the double glazing installer and those working in commercial glazing and other areas of the fenestration supply chain. These qualifications range from awards, certificates or diplomas. Some qualifications are information only, while others require the successful completion of practical tasks.   

Organisations providing the double glazing installer and the wider industry with qualifications are set up to provide this development work with the relevant regulatory bodies and Sector Skill Council requirements for added peace of mind. In addition, a substantial amount of industry experts are available throughout the development and consultation processes, ensuring the qualifications a double glazing installer has are meaningful, provide the individual with a valuable skillset and provide the customer with a professional, safe and secure installation.

These range from general window and door installations to installation and ongoing training in advanced curtain walling, glass manufacturing, glass supporting structures, window and door fabrication, surveying, physical glazing, fenestration warehousing and distribution, manufacturing techniques, fire-resistant glazing and others. There are many ways to demonstrate experience and professionalism in fitting windows and doors. 

Whilst not an essential requirement, professional window firms can also opt to work to current British Standards, one being BS 8213-4:2016 Windows and doors. Code of practice for the survey and installation of windows and external doorsets.

Fitting doors and windows on construction sites

double glazing installer moving glass windows on facade of business building

For fitting windows and doors on construction sites, the Construction Skills Certification Scheme (CSCS) is a card-based scheme providing proof that window company staff working on construction sites have the appropriate training and qualifications.

Holding a CSCS card is not a legal requirement, although most construction firms and housebuilders usually require construction workers on their sites to hold a valid card. CSCS cards prove that construction site operatives have the required qualifications and training for their individual roles. The benefit of CSCS cards is an entire site workforce, whether a double glazing installer, electrician, groundwork or other construction site operative, are all qualified and the widespread adoption of these cards ensures high standards and safety on UK construction sites.

Government and other professional organisations

For homeowners looking to replace their windows or needing new glazing for a building project, other organisations are designed to provide peace of mind and demonstrate qualified double glazing installers and tradespeople. TrustMark Home Pro is the Government Endorsed Quality Scheme covering work carried out in the home. Many window companies will apply as a TrustMark Registered Business, vetted to meet required standards, with an additional commitment to honest trading, customer service and technical training. 

You will also find organisations such as the Glass and Glazing Federation, Double Glazing & Conservatory Ombudsman Scheme, FairTrades. Which? schemes and others. All of these are set up to provide a vetting and approval process and ensure your double glazing installer provides quality products, good service and a professional installation.

More help and advice choosing a professional double glazing installer

We help thousands of homeowners and the trade every year, with advice and help, to find the right products from the best suppliers. Use our contact form to get in touch.

We’ve included some links to some of the best-known training and qualification organisations and other associations that can help with further information about double glazing installers and professional window companies.

Glass and Glazing Federation



GQA Qualifications