Double Glazing Installers – How To Choose The Right One

At times in the past the double glazing trade hasn’t perhaps had the best reputation but things have changed – the industry has cleaned up its act and, alongside improvements to regulations, is now thoroughly profession and reputable on the whole.

Let’s face it though, in any industry there’s always going to be companies to avoid – the cowboys if you like – and the double glazing industry is no different to any other in this respect so, in this feature we wanted to highlight the rules for double glazing installers and how to select a double glazing installer you can trust to do a great job.

Even now you can choose pretty much anyone to install your double glazing in the UK but don’t forget that replacement double glazing falls within the scope of building regulations. As such, any double glazing installer must comply with the current thermal performance standards, and you will need a certificate if you want to prove compliance with building regulations.

The vast majority of us homeowners aren’t going to know what the latest building regulations are, the rules that have to be followed and the current installation best practice which is why you need to ensure that you are working with professional experts who you can trust to carry out compliant, high quality installation works which are backed up with certification and guarantees.

This doesn’t necessarily mean going with the big national companies – there are many smaller regional installers who are able to provide everything you need in a competitive manner.

Double Glazing Installers – Where To Start?

It’s a legal requirement that new or replacement windows or doors must be installed in compliance with UK Building regulations. This has been law since 2002. There’s two choices to ensure this – you can either get the completed works signed off by an approved inspector or you can employ a contractor you are members of one of a self-certification bodies for the double glazing industry – the main two being FENSA or CERTASS whose combined membership covers almost 70% of the UK double glazing industry.

FENSA – Fenestration Self-Assessment Scheme

FENSA is a government-authorised scheme that monitors building regulation compliance for replacement windows and doors. Each FENSA Approved Installer, from large national brands to small local companies, is assessed regularly by us to ensure its compliance to building regulations is continually maintained.

Before entering into a contract with a double glazing installer you should always check if you’ll get a FENSA certificate which is recognised throughout the industry and covers the replacement of external windows, doors, roof windows and roof lights in your home, against the relevant Building Regulations. The certificate is not a guarantee but:

  • Confirms compliance with building regulations
  • Shows your installation’s energy efficient
  • Ensures it’s registered with the Local Council
  • Verifies your installer’s guarantee is insured
  • Helps when selling the property

FENSA’s mission:

“To improve window and door replacements across England and Wales, by professionalising installers and protecting homeowners.

We make sure the work complies with building regulations, is energy efficient, and registered with the local council. And verify that every FENSA Approved Installer’s guarantee is insured.”

Their website is:

To search for a FENSA double glazing installer member:


Like FENSA, CERTASS is also a competent person scheme approved by the UKAS. This competent person scheme falls under a Department of Communities and Local Government license. It is also accredited by TrustMark as a Green Deal certification body under the license from the Department of Energy and Climate Change.

CERTASS has been a Government authorised Certification body since 2006 and is UKAS accredited. This is something that really matters to them – in the words of CERTASS:

“It places a duty upon us to certify our members impartially against agreed standards. It requires that our certification provides confidence to all interested parties including consumers, Governments and industry”.

The process is simple – once your double glazing installation is complete CERTASS are notified by the contractor. CERTASS will then issue your certificate and automatically notify the local authority of the completed work. In addition they may also choose to carry out their own inspections on its contractors’ work as part of ongoing quality assessments.

Their website is:

To search for a CERTASS double glazing installer:

Double Glazing Installers – Additional Consumer Protection

In addition to self-certification compliance certification there are various other schemes that can add additional protection to the consumer. These include:

DGCOS – Double Glazing & Conservatory Ombudsman Scheme

The Double Glazing & Conservatory Ombudsman Scheme, or DGCOS basically lets you know who you can trust. It acts as a regulatory body that aims to protect consumers and improve the reputation of the glazing industry. It also mediates in case of disputes between the customer and the double glazing company.

The scheme acts to protect the interest of the consumer by ensuring ethical practices and high quality workmanship. DGCOS have a stringent 12 point accreditation process if a company wants to become approved by them.

DGCOS offers the buyer genuine consumer protection. All their members have been closely vetted in order that they can give a guarantee of exceptional service. So, if you use a DGCOS member you will receive high-quality consumer protection from when you sign the contract, throughout the installation process and continuing for the lifetime of your guarantee.

The benefits of entering into a contract with a double glazing installer who is a DGCOS member include:

  • Consumer advice line
  • Deposit and stage-payment protection insurance
  • Insurance-backed guarantee
  • Alternative dispute resolution
  • Access to an ombudsman

The DGCOS promise:

“Our promise to consumers is that you will receive genuine protection and can confidently place your order, knowing your home is in safe hands. DGCOS members are continually vetted throughout their membership to ensure they are trading ethically and providing consumers with a high level of service and satisfaction. We offer a network of quality installers who have the skills and knowledge to ensure your installation is an easy and enjoyable experience from start to finish.”

Their website includes a search facility which enables you to find a DGCOS double glazing installer near you:


TGAS – The Glazing Arbitration Scheme

The Glazing Arbitration Scheme (TGAS) is an independent ADR (alternative dispute resolution) scheme, which is the primary ADR scheme for the Glass & Glazing industry, plus other glazing related and home improvement products. TGAS is operated by a Chartered Trading Standards Institute certified ADR body, the Centre for Effective Dispute Resolution (CEDR).

This basically provides additional security and somewhere to turn in the event of a problem with the installation.


CPA – Consumer Protection Association

The CPA (and other similar organisations) provide insurance backed guarantees (IBG) and deposit protection schemes for construction, glazing & home improvements. Membership enables contractors & tradespeople to provide greater peace of mind to their customers peace of mind when purchasing products or services.

The CPA offers a range of products to make sure that consumers who enter into a contract to have work undertaken on their property are insured against unforeseeable circumstances such as tradesmen going into liquidation or administration. They offer:

  • A deposit protection service
  • An Insurance Backed Guarantee (IBG)
  • Financial services to ensure that the consumer is protected throughout, and after, the build or installation process.


Double GlazingTrade Associations

Membership of any trade association demonstrates a true commitment to the industry in respect of development, quality and best practice. The main trade body representing the double glazing industry in the UK is as follows:

The GGF – The Glass and Glazing Federation

The GGF represent companies that manufacture, supply or install glass and glazing products in the UK. Being the industry authority, the GGF promotes best practice and helps shape the highest technical and health & safety standards. The Federation is also the industry’s main voice in local and national politics influencing policy and legislation.

As well as offering an array of benefits to its members, the GGF guides and protects homeowners when buying glass or glazing products and services.


Double Glazing Installers – Choose Carefully

So, when deciding which double glazing installer to go with don’t just look at the cost. Check to see how professional they are …

  1. Check reviews on the various specialist review sites and talk to neighbours
  2. Check that they are a member of a competent person scheme approved by the UKAS such as FENSA or CERTAS
  3. Check additional memberships and accreditation
  4. Check the double glazing proposed is fully accredited
  5. Check the guarantees they are able to provide

Peace of mind counts so don’t just look at the price … look for the most cost-effective from all points of view.