Cost of Double Glazing Installation
across the UK

# Double Glazing Installation Trade Body Accreditation

The principal UK trade bodies overseeing double glazing installation are the Fenestration Self-Assessment Scheme (FENSA), the Glass and Glazing Federation (GGF), and the British Standards Institution (BSI). FENSA is particularly significant as it allows installers to self-certify their work and issue completion certificates that satisfy Building Regulations in most of England and Wales; membership means the installer has met technical standards and consumer protection requirements. The GGF represents manufacturers and installers across the industry and sets codes of practice, while BSI accreditation (such as ISO 9001 for quality management) signals compliance with international standards. Many accredited installers also hold Trustmark certification, a government-backed scheme that identifies legitimate traders and protects consumers against rogue traders. Understanding these distinctions helps you identify which credentials are most relevant to your installation project.

Verifying a provider's credentials is straightforward and essential. You can check FENSA membership directly on the FENSA register using the company's name or postcode, which will show whether they hold active certification and what work they are licensed to carry out. For GGF members, the federation's website provides a searchable directory, and Trustmark accreditation can be verified through the official Trustmark website. It matters because accreditation confirms the installer has undergone vetting, maintains ongoing standards, and operates under a complaints procedure; if something goes wrong, you have formal redress mechanisms. Accredited installers are also typically insured and their work often carries product warranties that are only valid when installed by approved operatives, protecting your investment long-term.

Accredited double glazing installers generally charge between 10 and 25 percent more than non-accredited alternatives, though the exact premium varies by region and company size. This