Independent laboratory testing has demonstrated that The Joinery Networkβs (TJN) Lignum timber side and top swing casement window delivers exceptional weather and security performance, reportedly placing it among the top-performing casement systems in the UK across all materials.
Led by Owen Dare, TJNβs technical director, Lignum has been subjected to a continuous development and testing programme with ERC Testing and CenSolutions.
The Lignum timber side and top swing casement window were put through the full BS 6375-1 weather performance testing alongside PAS24:2022 (2024) security assessment. The programme also introduced a new fixed sash option for glazed panels, further enhancing the Lignum range.

The Lignum casement recorded major gains across every key performance category:
- Watertightness (EN BS 12207): Increased from 250Pa to 600Pa hitting 9A, the highest classification, with zero water ingress.
This represents resistance to wind-driven rain equivalent to 70mph, up from 45mph, without leakage. - Wind Resistance (EN BS 12208): Achieved Class C5, the highest-pressure classification.
- Air Permeability (EN BS 12210): Achieved Class C4, the highest level possible
Alongside weather performance, the system passed PAS24:2022 (2024) security testing, meeting the latest enhanced security requirements without sacrificing performance or design.
The new Lignum Conservation casement window with traditional butt hinges, has also been in the test lab achieving PAS24:2022 (2024) with both top and side hung sashes. TJN reports that there was no need for hinge bolts during testing.
Lignum double doors open out
The Lignum double doors open out also achieved PAS24:2022. And again, showed improved results on weather testing.
- Air Permeability (BS EN 12207) now 600pa Class 4 which is the highest rating.
- Watertightness (BS EN 12208) also went all the way up to 600pa with no leakage for a 9A performance which again is the highest possible.
- Wind Resistance (BS EN 12210) improved to the highest level of 1200pa Class A3.
Owen commented. βThe Lignum casement sets a new benchmark and now sits at the very top of the market, not just for timber, but when measured against the high-performance PVC-U and aluminium systems as well.
βThe new Lignum Conservation Casement extends the options for property owners looking for traditional design with the latest high security. Itβs excellent news for The Joinery Network manufacturers.
βThe re-testing on the Lignum doors was very impressive, and I am very proud of the results.β
Further testing is already underway to extend certification across the wider Lignum window and door range, supporting the continued growth of The Joinery Network of Lignum manufacturers.