A Safer, More Sustainable Home for Vulnerable Adults
Pyramid Eco installed high-performance exterior wall insulation (EWI) to support the transformation of a solid-wall property into energy-efficient housing for vulnerable adults.
This before and after external wall insulation case study shows how a non-combustible mineral wool system was used to improve fire safety, comfort, and long-term performance.
Project Snapshot:
Location: 41 Sidney Avenue, South East England
Property Type: Early 20th-century solid-wall, end-terrace
Client Role: Architect and project lead
Purpose: Full retrofit and conversion into accessible housing
Solution: External wall insulation (EWI) using mineral wool
System: Webertherm XM by Saint-Gobain
The Challenge
The client was leading the renovation of a solid-wall home into accessible, supported housing. The project included major upgrades such as internal hoists, ramps, low-carbon heating, solar PV, and underfloor insulation.
To meet modern energy standards and ensure long-term performance, the building fabric required high-quality external wall insulation. The client required a specialist partner capable of delivering a fire-safe, regulation-compliant system while coordinating within a complex, multi-trade site.
Why Pyramid Eco?
The client returned to Pyramid Eco based on a trusted previous relationship and a clear understanding of our strengths. They needed a team that could deliver safely, efficiently, and without compromise.
Clear, honest advice
We explained the long-term benefits of mineral wool compared to cheaper alternatives, helping the client make an informed, future-ready choice.
Specialist retrofit knowledge
Our experience with solid-wall properties and live renovation sites allowed us to plan and install with confidence, even in complex conditions.
Commitment to safety
We only use non-combustible mineral wool for exterior wall insulation, ensuring better fire resistance and long-term compliance.
Reliable delivery
Despite delays from other contractors, we stayed responsive and focused on quality. The EWI was completed to the highest standards.
Our Approach: A Fabric-First Retrofit
Working with the client’s initial design specification, Pyramid Eco collaborated with Weber (now Saint-Gobain Exterior Solutions) to finalise the insulation system. We delivered a complete mineral wool-based EWI installation, designed for fire safety, moisture protection, and thermal performance.
Specification Summary:
System: Webertherm XM
Insulation Type: Mineral Wool
Supplier: Weber/Saint-Gobain
Coverage: Full external walls, with adjustments for flashing, window reveals, and boundary details
From the outset, we made it clear that EPS (expanded polystyrene) — while still legal — was not part of our offering due to its combustibility and long-term risks. The client appreciated this transparency and opted for the safer, more robust mineral wool system.
Related: Why Pyramid Eco Is Saying Goodbye to EPS Insulation
Overcoming Key Challenges
This was not a simple insulation install. Our team worked within a dynamic site environment, with various other contractors managing roofing, glazing, heating, and internal works.
1. Site Coordination and Shared Scaffolding
Scaffolding had to be shared with roofers and window installers. This created access limitations and needed careful planning to avoid delays or unsafe overlaps.
2. Window Integration Complications
The windows were managed by a third-party agent. Due to poor communication, sill depths varied across the property, leading to visible inconsistencies. Our team adapted finishing details to accommodate the errors as best as possible.
3. Boundary Constraints and Chimney Details
The home had prominent chimney breasts, and one side bordered a communal walkway. Adding 100mm of external insulation raised the risk of encroachment and thermal bridging. We collaborated with the project team to apply internal insulation to key sections, minimising heat loss while respecting property lines.
4. Regulation Changes Mid-Project
Updated guidance around roof abutments required denser insulation near moisture-prone areas. We adjusted the system design accordingly to meet current regulations — ensuring eligibility for both the manufacturer’s and the insurance-backed guarantees.
5. Timeline Delays from Other Trades
Although EWI installation typically takes 3–4 weeks, delays to roofing and window works, combined with summer holidays and wet weather, extended the project to 3 months. Pyramid Eco remained responsive throughout, maintaining progress while prioritising quality and compliance.
Related: External Wall Insulation Cost in 2025: Complete Price Guide, Savings & Grants
Results and Benefits
Pyramid Eco’s exterior wall insulation played a key role in upgrading this solid-wall property into a warm, efficient, and safe home for vulnerable adults. While other upgrades contributed to the outcome, the EWI alone is estimated to have added 10 to 15 points to the EPC rating.
Key outcomes:
- Improved year-round comfort for future residents
- Enhanced fire safety with non-combustible mineral wool
- Reduced heat loss and thermal bridging in problem areas
- Increased long-term value and compliance with housing standards
- Supports a likely A-rated EPC, lowering future energy costs
All work is protected by robust guarantees and full compliance:
- 10-year manufacturer’s guarantee from Weber
- 25-year insurance-backed guarantee, even if the manufacturer or installer is no longer in business
- Full compliance with building regulations and industry standards
Client Satisfaction
The client was very happy with the results. They appreciated the team’s professionalism, clear advice on material choices, and ability to deliver a safe and energy-efficient property despite the complex multi-trade environment. The EWI met all regulatory standards and complemented the broader renovation, helping the property achieve long-term energy performance and compliance.
Ready to Retrofit with Confidence?
Improve comfort, safety, and energy performance with expert support from Pyramid Eco. We deliver certified exterior wall insulation using non-combustible materials, installed to the highest standards and backed by trusted guarantees.
Whether you’re improving a home or managing a larger retrofit, we make the process clear and reliable from the start.
