Planning new windows or doors for your home is an exciting project. But once you start researching local installers, you'll quickly come across terms like CERTASS, building regulations and competent person schemes, and it's not always clear what any of it actually means for you.
This guide breaks it all down in plain English. By the end, you'll know exactly what to look for when choosing a double glazing installer in Hertfordshire or Essex, why CERTASS certification matters and how it protects you as a homeowner.
What is CERTASS and why does it matter?
CERTASS is a government-authorised Competent Person Scheme for the glazing industry. In simple terms, it allows registered installers to self-certify that their work complies with current building regulations, without you needing to apply for separate local authority building control approval.
When a CERTASS-registered company installs your windows or doors, they take on full responsibility for making sure the work meets the required standards. Once the job is complete, they issue you with a CERTASS certificate, which is your official proof that the installation is building regulations compliant. This document is important when you come to sell your home, as solicitors and buyers will want to see it as part of the conveyancing process.
Without this certificate, you may need to apply retrospectively for a building regulations certificate through your local council, which can be both time-consuming and costly.
Why building regulations compliance matters for Hertfordshire homeowners
In England and Wales, replacing windows and doors in a home is classed as controlled work under Part L of the Building Regulations. This covers energy efficiency requirements, meaning any new installation must meet minimum thermal performance standards.
If you hire an unregistered installer who does not self-certify their work, the responsibility falls on you as the homeowner to ensure compliance. That could mean additional inspections, paperwork and costs that you could have easily avoided by choosing a CERTASS-registered company from the start.
For homeowners across Hertfordshire and Essex, the CERTASS website allows you to verify that any installer you're considering is genuinely registered and up to date with their membership.
How does CERTASS protect your deposit?
One of the most valuable but least talked about benefits of using a CERTASS-registered installer is deposit protection.
CERTASS membership includes a consumer protection element, which means your deposit is safeguarded if the company ceases trading before your installation is complete. For anyone spending several thousand pounds on new windows or doors, that peace of mind is significant.
This is particularly important when you're dealing with a local business rather than a national brand. A CERTASS certificate gives you assurance that the company operates to a verified standard and that your money is protected should anything go wrong.
What questions should you ask a glazing installer before hiring them?
Knowing the right questions to ask can save you a lot of trouble later. Here's what to check before you commit to any installer in Hertfordshire or Essex.
Are you CERTASS registered? Ask for their membership number and verify it directly on the CERTASS website. A genuine member will have no issue providing this.
Will you provide a CERTASS certificate on completion? This should be a standard part of the service. If an installer is vague about issuing paperwork, that's a warning sign.
Do your products meet current energy efficiency standards? New windows and doors must meet the thermal performance requirements set out in Part L of the Building Regulations. Ask about the energy ratings of the products they install.
Do you carry public liability insurance? Any reputable installer should be able to provide evidence of this without hesitation.
Can you provide references or reviews from local customers? An established local installer with a track record in Hertfordshire or Essex should have no shortage of happy customers willing to vouch for their work.
What's the difference between CERTASS and FENSA?
You may also come across FENSA when researching installers. Both are government-authorised Competent Person Schemes that cover the replacement of windows and doors, and both allow registered installers to self-certify compliance with building regulations.
The key difference is that CERTASS tends to be more widely used by independent local installers, while FENSA has a higher proportion of larger national companies among its members. For homeowners in Hertfordshire and Essex, either scheme offers the same legal protection. What matters is that your installer is registered with one of them.
Why choose a local CERTASS installer over a national company?
There are real advantages to working with a local, independently run glazing company rather than a large national brand.
Local installers rely heavily on their reputation within the community. In areas like Stevenage, Harlow and across Hertfordshire, word travels fast, so a good local company has a strong incentive to get the job right first time. You're also more likely to deal directly with the people carrying out the work, rather than going through layers of call centres and subcontractors.
At Affordable Windows, we've been installing windows and doors for homeowners across Hertfordshire, Stevenage, Harlow and Essex since 2012. As a CERTASS-registered company, every installation we carry out is fully compliant with current building regulations and comes with the necessary certification as standard. You can find out more about our full range of services on our windows and doors page.
What types of windows and doors require building regulations compliance?
Any replacement window or external door in a domestic property in England falls under the building regulations. This includes:
Replacement double glazing in any room. Front and back doors, including composite, uPVC and timber. French doors and patio doors. Bifold doors. Roof windows and skylights in habitable rooms.
New builds and extensions are subject to additional regulations, but for the majority of homeowners in Hertfordshire and Essex looking to replace existing units, the key requirement is that the work is carried out by a Competent Person Scheme member or independently inspected by your local building control authority.
How to check if an installer is genuinely CERTASS registered
Unfortunately, not every company that claims to be CERTASS registered actually is. Before you sign any contract or pay a deposit, take a few minutes to verify the installer's membership directly on the CERTASS website using their postcode or company name. It takes less than a minute and could save you significant problems later.
You should also check that their membership is current. Some companies may have been registered in the past but allowed their membership to lapse. An up-to-date registration means they are actively meeting the scheme's requirements and are covered by its consumer protection provisions.
Frequently asked questions
Do I need a CERTASS certificate when I sell my home?
Yes. When you sell a property, your solicitor will request evidence that any window or door replacements carried out since 2002 were either self-certified by a Competent Person Scheme member or approved by building control. A CERTASS certificate is the simplest way to satisfy this requirement and avoid delays in the sale process.
What happens if my installer didn't provide a CERTASS certificate?
If your installer was CERTASS registered at the time of the work, you may be able to request a replacement certificate directly from CERTASS. If the work was not self-certified, you may need to apply to your local council for a regularisation certificate, which involves an inspection and a fee.
Is CERTASS the same as a guarantee on the windows?
No. CERTASS certification confirms that the installation meets building regulations. It is separate from any product or installation guarantee offered by the manufacturer or installer. Always ask for the terms of any workmanship or product guarantee in writing before signing a contract.
Can I use a CERTASS installer for new build properties?
CERTASS primarily covers replacement windows and doors in existing domestic properties. New build properties typically require full building regulations approval through your local authority rather than self-certification. If you're unsure, speak to your installer or local building control office for clarification.
How do I find a CERTASS installer in Hertfordshire or Essex?
You can search for registered installers directly on the CERTASS website by entering your postcode. Alternatively, if you're based in Stevenage, Harlow or the surrounding areas, get in touch with the Affordable Windows team and we'll be happy to talk you through your options and provide a free, no-obligation quote.
Does CERTASS cover composite doors and uPVC doors?
Yes. CERTASS covers the replacement of all types of external doors in domestic properties, including composite, uPVC, aluminium and timber. As long as the installer is registered and the products meet the required energy efficiency standards, the installation can be self-certified under the scheme.
