North Homes, Social Housing

Project overview

Wood Lane Court and St Mary’s Court are two residential blocks owned by 54 North Homes that underwent a major retrofit programme to improve energy efficiency, fire performance and long-term durability. The project formed part of a wider decarbonisation strategy, targeting reduced heat loss, improved occupant comfort and compliance with current retrofit standards.

The works were delivered in partnership with Equans and included external wall insulation (EWI), upgraded heating systems and improved ventilation across 98 occupied homes.

The challenge

The project presented several technical challenges typical of occupied retrofit schemes:

• Mixed construction types, including masonry and timber frame substrates
• Multiple balconies, passageways and recessed areas requiring careful detailing
• Existing asbestos-containing roof coverings at Wood Lane Court, limiting roofline alterations
• The requirement to deliver PAS-compliant retrofit detailing without disturbing the existing roof structure
• A need to significantly improve thermal performance while maintaining safe, robust façade junctions

The solution

A Wetherby stone wool external wall insulation solution was specified to address both thermal and fire performance requirements. The system was installed to a mix of masonry and timber frame substrates and incorporated non-combustible ROCKWOOL stone wool insulation, achieving an A2 fire rating.

At Wood Lane Court, one of the key technical innovations was the use of Wetherby’s PAS-approved roofline closure system on the gable elevations. Rather than extending the façade up to the asbestos roof, the system was carefully dropped below roof level and detailed using a brick slip soldier course to maintain weather protection and continuity of insulation without disturbing the roof covering.

The roofline detail followed Wetherby Detail A4, incorporating a grind-in profile suitable for limited existing roof overhangs. This approach ensured effective protection against rainwater ingress and thermal bridging while maintaining compliance with retrofit standards.

Installation

The EWI works were carried out by Thomas Niamh Contracting Ltd, a Wetherby-recognised contractor and INCA member. The system build-up comprised:

• 12mm sheathing board
• 100mm non-combustible stone wool insulation mechanically fixed to the substrate
• Reinforced basecoat and thin-coat silicone render finish

At St Mary’s Court, additional timber framing and sheathing boards were installed within passageways to accommodate the insulation system and ensure continuity of performance around complex junctions, including doorways and balconies.

Finishes and detailing

Both buildings were finished using Wetherby HECK 4S Silicone ‘K’ 1.5mm textured render. Multiple colour tones were used to articulate the façades, with darker colours at ground level and lighter finishes to upper elevations to improve visual balance and reflectivity.

Careful attention was given to detailing around balconies, walkways and recessed elevations to ensure durability, weather resistance and long-term performance in high-exposure areas.

The result

The completed works delivered a substantial uplift in thermal performance, with external wall U-values improved from approximately 1.41 W/(m²K) to 0.28 W/(m²K). The upgrade is expected to significantly reduce energy demand, lower carbon emissions and improve internal comfort for residents.

The integrated roofline closure system provides long-term protection against water ingress and thermal bridging, enhancing the overall effectiveness and lifespan of the EWI installation.

Key facts

• System: Stone wool external wall insulation with PAS-compliant roofline closure
• Substrates: Masonry and timber frame
• Insulation: 100mm non-combustible stone wool
• Finish: Silicone thin-coat render
• Fire performance: A2-rated system
• U-value improvement: From ~1.41 to 0.28 W/(m²K)