SlimLite’s Full BS EN 1279 Certification – and Why It Matters for Your Projects

SlimLite is one of only two companies in the UK with full BS EN 1279 Parts 1–6 certification. If you work on listed buildings or conservation projects, here's why that should matter to you.

What is BS EN 1279?

It's the British and European standard for insulating glass units – covering everything from gas retention and moisture resistance to durability, edge seal performance and factory production controls. It has six parts. Most manufacturers only certify to some of them. SlimLite holds all six, including the critical Parts 2 and 3, which the majority of suppliers skip.

SlimLite holds all six, including the critical Parts 2 and 3, which the majority of suppliers skip.

What the Full Certification Covers

  • Part 1 – General conformity

  • Part 2 – Moisture penetration resistance (long-term tested)

  • Part 3 – Gas leakage rate and tolerances (long-term tested)

  • Part 4 – Physical attributes of edge seals

  • Part 5 – Evaluation of conformity

  • Part 6 – Factory production control

What It Means for Your Business

Planning compliance, without the headache.

Performance that's proven, not promised.

Fewer callbacks. Less risk

Confidence on heritage projects

Built for Heritage Work

Our slimline IGUs are designed to fit original period frames, replicating the proportions of single glazing while delivering modern thermal performance. Aesthetically sympathetic. Technically compliant. Fully certified.

Work With a Supplier You Can Trust

Joinery companies across the UK rely on SlimLite for heritage and conservation glazing. As a trade partner, you get certified products, competitive pricing, technical support and full documentation for every project.

© Copyright 2026 SlimLite Group Ltd