Passive timber frame wall system

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Natural, breathable wall panel system

Our Passive wall system is engineered to deliver exceptional thermal efficiency and airtightness. Using Steicozell wood-fibre insulation for its low-carbon credentials, each wall panel forms part of a fully breathable, sustainable envelope. The system is available in 240mm, 300mm, 360mm, and 400mm depths.

The 240–360mm panels are built to passive principles, while the 400mm option achieves full Passive House certification. This system provides a robust, energy efficient envelope that balances outstanding comfort, long-term durability and energy savings.

Our passive wall systems

U-value 0.15W/m²K

Thickness: 240mm

U-value 0.13W/m²K

Thickness: 300mm

U-value 0.11W/m²K

Thickness: 360mm

U-value 0.10W/m²K

Thickness: 400mm

Passive wall build up

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External Finishes*

*supplied by others

External Sheathing - OSB/3/Decking

Ventilated Cavity

Breather Membrane

STEICOjoist® LVL/NFB & STEICOzell® Blown Wood Fibre Insulation

12.5mm SmartPly ProPassiv airtight OSB

Battened Services Void

Plasterboard: 30mins FR: 15mm Type A or F *

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Features of our Passive Wall

Airtightness: Achieves airtightness levels below Passive House (<0.6 ACH) when installed in conjunction with a suitable ventilation system
Natural performance materials: STEICOzell woodfibre insulation and responsibly sourced timber.
Breathable construction: Hygrothermal stability that mitigates condensation risk and enhances indoor comfort.
Sustainability first: ~81% woodfibre composition; renewable and low embodied carbon.
Precision manufacturing: Off-site fabrication ensures dimensional accuracy and programme certainty.
Efficient assembly: Large-format pre-insulated panels, optional integrated joinery, and rapid weathertightness.
Fire resistance: Fire approved to BS EN 1365-1:2012 (load bearing wall) and BS EN 1363.1:2020
Embodied carbon: Significantly lower than conventional wall systems.

Compliance & compatibility

Compatible with: our Passive roof system, AerosealUK's air sealing technology, AeroBarrier and our wider product portfolio.
Standards: designed to exceed UK Building Regulations and Passive House certification.
STA Assure Gold certified