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2026-01-22 · guides

FENSA vs Certass: What These Window Certifications Mean for You

Both schemes are government-approved Competent Person Schemes — but there are differences. We explain what matters when choosing a window installer.

When you replace windows or doors in England and Wales, the installation must comply with Building Regulations. There are two ways to demonstrate compliance: a Building Control inspection (slow and expensive) or installation by a Competent Person Scheme member. The two main schemes are FENSA and Certass — and many homeowners aren't sure which is which.

What FENSA does

FENSA (Fenestration Self-Assessment Scheme) was set up in 2002 by the Glass and Glazing Federation. It's the largest of the Competent Person Schemes with over 8,000 registered companies. FENSA members self-certify their installations and FENSA carries out spot audits — typically inspecting a percentage of completed jobs annually.

What Certass does

Certass operates similarly to FENSA but with stricter on-site audit requirements and a different governance structure. Some installers prefer Certass for its perceived higher inspection rate; some prefer FENSA for its larger network and broader recognition.

From the homeowner's perspective

Both schemes provide identical legal compliance. Both issue certificates that satisfy Building Control, mortgage lenders and conveyancers. Both offer insurance-backed warranties on member installations. The choice between them is largely a matter of installer preference, not consumer impact.

What to check on your certificate

After your installation, you should receive within 30 days: a FENSA or Certass certificate showing the job address, installation date, and registered installer; an insurance-backed warranty covering 10 years against installer default; and a building regulations compliance certificate. Without these, you may struggle when selling the property.

S&K Glazing's accreditations

We're FENSA-registered and members of the Glass and Glazing Federation. Every installation includes FENSA certification, a 10-year insurance-backed warranty, and full building regulations compliance documentation. Call 0800 088 6341 for a free quote.

Need help with your glazing project? S&K Glazing offers free surveys and fixed-price quotes across the UK. Call 0800 088 6341, message us on WhatsApp at 07830 175306, or request a quote online.

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