Prospective members are rigorously vetted before being allowed to join our national network of accredited installers. The implementation of our vetting procedure means that a number of glazing companies who apply to join DGCOS do not satisfy our accreditation requirements. DGCOS also carries out frequent audits and monitors level of customer satisfaction.


  • Undergo a five point credit and background history check on the proprietors/directors which includes multiple phoenix checks, credit scores, CCJ checks and similar trading name checks.

  • Carry minimum insurances of a) £2m Public Liability b) £10m Employers Liability.

  • Provide every customer with a Written Contract (to include Terms and Conditions and cancellation rights).

  • Provide every customer with a Written Guarantee.

  • Provide every customer with Deposit Protection Insurance (where a deposit has been taken - up to a maximum of 25% of the contract value).

  • Provide every customer with an Insurance Backed Guarantee.

  • Comply with building control regulations on every installation deemed necessary.

  • Allow DGCOS Inspectors to inspect any installation deemed necessary.

  • Allow DGCOS to send every customer a Satisfaction Questionnaire.

  • Submit to the legal jurisdiction of DGCOS and the Ombudsman.


  • Every customer is automatically sent a Satisfaction Questionnaire and pre-paid envelope.

  • These replies are entered into the DGCOS performance system and results monitored.

  • Annual review of credit checks and public/employer liability insurances.

Your internet browser is not supported with this website. Download a free, up-to-date browser here. ×