Cost of Double Glazing Units
across the UK

# Double Glazing Units Trade Body Accreditation

The main regulatory frameworks governing double glazing in the UK include FENSA (Fenestration Self-Assessment Scheme), which is the primary competent person scheme for window and door installation and carries legal weight under Building Regulations. The British Standards Institution (BSI) sets technical standards such as BS 6375 for window performance, while the Glass and Glazing Federation (GGF) represents manufacturers and installers and provides its own quality assurance programme. Additionally, the Competent Person Scheme operated through FENSA ensures that installers have met stringent technical and business standards. Understanding these bodies matters because FENSA registration, in particular, is a legal requirement for most window installations in England, Scotland, and Wales, and non-compliant work can affect property insurance, future sales, or result in enforcement action.

To verify a provider's credentials, ask for their FENSA registration number and check it directly on the FENSA website, which holds a searchable register of all accredited installers and their coverage. You can also request proof of BSI kitemarking for the units themselves, GGF membership, or relevant certifications from the manufacturer. Most reputable companies will display these credentials prominently on their website or marketing materials. It is worth taking this step because accreditation demonstrates that a company has undergone independent assessment of its technical competence, business practices, and customer service standards. Working with an accredited provider protects you legally, ensures warranty validity, and provides recourse if something goes wrong through their dispute resolution processes.

Accredited double glazing providers typically charge between five and fifteen percent more than unaccredited competitors, reflecting the costs of annual audits, training, insurance, and compliance management. This premium is generally justified because it eliminates the risk of paying for work that fails to meet Building Regulations, which could