For architects & specifiers
Specification
What you need to write Lignum into a specification: the standards, the guarantees, the glazing performance and the range. If what you need is not here, ask — we would rather send you the tested figure than have you work from an assumption.
Lignum is the timber window and door system of The Joinery Network, built by approved manufacturers across the UK to one specification and one set of drawings. Wealden Joinery is an approved Lignum manufacturer and has been making timber windows and doors in Sussex since 1994.
Guarantees
What is covered, and for how long
All transferable to a new property owner.
| Cover | Period | Notes |
|---|---|---|
| Rot and fungal decay | 30 years | Engineered, treated timber sections with fully sealed joints. |
| Workmanship | 10 years | Covers manufacture of the unit as supplied. |
| Paint finish | 10 years | Factory-applied microporous coating systems. |
| Hardware | 10 years | Locks, hinges, friction stays, handles and ironmongery. |
| Glazing | up to 15 years | Includes vacuum units; performs well beyond 25 years. |
Certification
Standards and compliance
Tested and certified as supplied.
PAS 24:2022
Enhanced security performance for doorsets and windows.
Secured by Design
Police-preferred specification.
Approved Document Q
Security in new dwellings.
Approved Document L
Conservation of fuel and power: thermal performance.
Approved Document M
Access and use of buildings: thresholds and operation.
BS 6375-1:2009
Weather tightness: air, water and wind resistance.
FSC® chain of custody
Responsibly sourced timber throughout the supply chain.
Glazing
Performance figures
Glazing is specified with the frame, not bolted on afterwards. Vacuum glazing gives a slimmer, lighter unit that outperforms triple glazing — which is what a conservation officer will accept and a triple-glazed unit will not.
Thermal (vacuum glazing)
From 0.49 W/m²K
Typical 0.5 Ug.
Acoustic
Up to 36 dB reduction
Typical 36 Rw dB, independently tested.
Slimmest unit
6.15 mm
Light transmission
Up to 80%
Also available
Slimline heritage double, laminated acoustic, decorative, obscure, restoration
Timber
What it is made from
Accoya®
Modified softwood with exceptional dimensional stability and rot resistance. Carries a 50-year guarantee option and is the default where exposure or movement matters.
Engineered hardwood
Laminated for stability, for period work and where a hardwood is specified.
Engineered softwood
For painted work where budget matters more than the longest possible service life.
Sections
Window and door types
Box sash
Traditional hidden counterweights and pulleys, 75mm slim frames, traditional horns, staff beads and decorative glazing bars. Suitable for Grade I, II* and II listed buildings.
Spring balance sash
Sash operation without the box, where the reveal will not take a box frame.
Flush casement
Sash closing flush with the frame face, the period-correct casement detail.
Storm-proof casement
Sash lapping over the frame, for exposed elevations.
Alu-clad
Timber internally, aluminium externally, for low-maintenance and contemporary elevations.
Range
What is available
windows
Flush casement · flush · wood-aluminium · box sash · spring balance · heritage · restoration · shaped
doors
Entrance · French · bifold, with matching sidelights, toplights and frames
accessories
Centor integrated screens and blinds · coordinated ironmongery collections
finishes
Full RAL · curated shades · natural woodstains · dual colour · grain-enhancing
Documentation available on request
- •Test certificates and declarations of performance
- •U-value calculations for a specific configuration
- •FSC® chain-of-custody certification
- •Insurance certificates and written guarantee documents
- •Conservation and planning support letters
- •NBS-style specification clauses
Conservation
Listed buildings and conservation areas
Conservation-area and listed-building work is routine rather than exceptional here. Period colour palettes, traditional sash mechanisms, authentic horns and glazing bars, and slim-sightline glazing are all available where an authentic detail has to be matched. Bring us the drawings and the conservation officer’s comments and we will tell you what will pass.