What’s The Difference Between FENSA and Assure Certified Installer?
Replacing your windows or doors? You’ll likely encounter the terms FENSA and Assure. Both are Competent Persons Schemes, designed to ensure installations comply with UK Building Regulations. But what sets them apart?
Since 2002, all replacement windows and doors must meet these regulations. Trade body schemes like FENSA and Assure allow installers to self-certify their work.
In this guide, we’ll look at the key differences between Assure and FENSA so you can make an informed decision before choosing a double glazing company to work with.
Let’s dive in.
What is FENSA?
FENSA, the Fenestration Self-Assessment Scheme, is a UK government-backed initiative for replacement window and door installations. Established to streamline Building Regulations compliance, it allows registered installers to self-certify their work. This eliminates the need for individual council inspections, saving homeowners time and money.
Upon completion, a FENSA certificate is issued, confirming adherence to energy efficiency and safety standards. This certificate is vital when selling a property, as it provides proof that the work was legally compliant. FENSA also ensures installations are registered with the local council, maintaining accurate property records.
FENSA is a familiar name, having been around longer and boasting a larger membership.

What is Assure?
Assure is a UKAS-accredited scheme, authorised by the MHCLG.
Assure is a UKAS-accredited Competent Persons Scheme authorised by the Ministry of Housing, Communities and Local Government (MHCLG) for the replacement of windows, roof windows, roof lights, and doors in England and Wales. Essentially, it ensures that these installations comply with the relevant Building Regulations.
Here’s a breakdown of what that means:
- UKAS Accreditation – This signifies that Assure is independently assessed and meets rigorous standards, adding a layer of credibility.
- Competent Persons Scheme – It allows registered installers to self-certify that their work complies with Building Regulations, rather than requiring individual council inspections.
- Focus on Compliance – Assure verifies that installations meet energy efficiency, safety, and other regulatory requirements.
- Auditing and CPD – Assure places a strong emphasis on auditing its member’s installations and ensuring that installers undertake continual professional development (CPD) to keep up to date with the latest regulations.
- Insurance-Backed Guarantees – Assure installations are covered by insurance-backed guarantees.
- Independent Audits – Assure performs independent audits of sample installations.
In short, Assure provides homeowners with assurance that their window and door replacements are carried out to the highest standards and in full compliance with the law.
So, is an assure certificate the same as FENSA? In short, yes. Like FENSA, it ensures compliance with regulations but emphasises ongoing installer audits and continual professional development (CPD).

Key Differences and Similarities
While FENSA has a larger presence, however, Assure is rapidly gaining traction.
Both provide crucial reassurances:
- Compliance: Both ensure installations meet Building Regulations.
- Protection: Both offer deposit protection and insurance-backed guarantees.
- Standards: Both enforce strict training and competence standards.
- Dispute Resolution: Both offer mediation for disputes.
- Auditing: Assure has a strong emphasis on regular auditing of installers and also performs independent audits of sample installations.
Why Do You Need a Window Installer Certification?
A window installer certification, like FENSA or Assure, is essential for demonstrating compliance with UK Building Regulations. It ensures installations meet energy efficiency and safety standards, crucial for property value and homeowner safety.
Certification provides proof that work is legally sound, avoiding potential issues during property sales. It also eliminates the need for individual council inspections, streamlining the process. Certified installers are vetted, guaranteeing competence and adherence to best practices.
Additionally, these schemes often offer insurance-backed guarantees, protecting homeowners from faulty workmanship or product defects, and offering peace of mind.
Phair Windows and Assure
At Phair Windows, we’re proud to be Assure certified. This demonstrates our dedication to providing high-quality, compliant installations. We believe Assure’s rigorous standards and independent audits offer our customers added peace of mind.
Whether you choose an installer registered with FENSA or Assure, always request your certificate upon completion. This document is your proof of compliance and a valuable asset for your home.
Need a Quote?
If you’re looking to replace your windows and doors, contact the experts at Phair Windows. We help homeowners across Leicestershire and the East Midlands with new windows, doors, porches, rooflines, conservatories and other home improvement services.
Whether you’d like some advice or a free quote, contact our team today!
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