Case Study

Posted on 27th April 2026 at 16:55

CASE STUDY

Project Overview

Sector: Residential

Location: Hertfordshire

Scope: Retrofitting external wall insulation (EWI) with a premium silicone coloured render finish to improve energy efficiency, reduce heat loss, and enhance the aesthetic appeal of an existing private home.

Efficient Build Ltd was commissioned to upgrade an existing residential property in Hertfordshire, combining high-performance insulation with a visually striking silicone coloured render. The project aimed to deliver energy savings, improved internal comfort, and a durable, modern exterior while minimising disruption for the homeowners.

Project Objectives

Retrofit existing walls with high-performance insulation to significantly reduce heat loss Improve the property’s EPC rating and long-term energy efficiency Apply a breathable, weather-resistant silicone coloured render for aesthetic and structural enhancement Ensure minimal disruption to the homeowners’ daily life during installation Deliver long-term durability, thermal efficiency, and visual appeal

Challenges & Considerations

The property was an older residential house with uneven external walls requiring careful preparation for insulation installation Ensuring full compliance with building regulations and thermal performance standards for retrofits Maintaining the integrity of existing structural elements while upgrading the envelope Coordination of works to minimise inconvenience for the occupants

Project Outcomes

Enhanced Energy Efficiency: Reduced heat loss and improved thermal comfort, lowering energy bills for the homeowners

EPC Improvement: Retrofit increased the property’s energy performance rating, enhancing long-term value

Premium Visual Upgrade: Smooth, durable silicone coloured render provides a modern, high-end façade

Minimal Disruption: Professional site management ensured residents experienced minimal inconvenience

Long-Term Performance: Insulated and rendered walls maintain energy efficiency, weather resistance, and aesthetic appeal for years

Our Approach

Efficient Build Ltd approached the retrofit project with meticulous planning, professional project management, and technical precision:

Comprehensive Site Survey & Assessment - Evaluated wall conditions, moisture levels, and structural integrity. Determined optimal insulation board thickness and render specification. Developed a tailored plan for minimal disruption to residents

Preparation & Surface Stabilisation - Existing walls were cleaned, repaired, and primed. Any cracks, weak plaster, or damage were addressed to ensure long-lasting adhesion of insulation boards and render

High-Performance Insulation Installation Precision - installation of external wall insulation boards over the existing façade. Focus on airtight sealing to reduce thermal bridging and improve overall energy efficiency

Silicone Coloured Render Application - Breathable, weather-resistant silicone render applied over the insulated surface. Expert detailing around windows, doors, and edges to ensure durability and visual perfection. Choice of colour tailored to modernise the property while complementing local aesthetics

Final Finishing & Quality Assurance - Meticulous inspection of render finish and insulation installation. Ensured compliance with energy efficiency standards, safety regulations, and building codes

Project completed with minimal mess, respecting the occupied home environment

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