Case Study: The Box Project – Plymouth

Willmott Dixon appointed Duratite to undertake a large-scale soffit insulation installation at The Box Project — a landmark museum and cultural centre in Plymouth. The project formed part of an internal thermal upgrade to improve energy efficiency and prevent condensation across the exposed structural soffits beneath the concrete floors.

The concrete soffits required a robust insulation solution capable of delivering exceptional thermal performance, moisture resistance, and air tightness within tight access areas. Traditional insulation boards were unsuitable due to the irregular surface profile and extensive service penetrations.

Duratite specified and applied Enverge Nexseal LE closed-cell spray foam, providing a continuous, fully bonded insulation layer with no joints, gaps, or thermal bridges.

The Duratite installation team prepared the exposed concrete surfaces by cleaning and degreasing all soffit areas before application. Once masked and protected, the spray rig was calibrated to manufacturer’s specification to ensure consistent output, pressure, and mix ratio.

A total of 787m² of concrete soffit was insulated with 120mm of Enverge Nexseal LE closed-cell spray foam, achieving an overall U-value of 0.18 W/m²·K.

The application was carried out under strict Health & Safety and quality control procedures, including:

• Controlled access and ventilation measures during spraying
• Full PPE and breathing protection for operatives
• Substrate temperature and humidity monitoring
• Post-application adhesion and thickness checks

All works were completed on schedule and in coordination with other trades on site.

Enverge Nexseal LE was selected for its ability to deliver high thermal efficiency (λ = 0.027 W/m·K) combined with rigidity, strength, and moisture resistance — essential for soffit applications. The product’s closed-cell composition prevents air leakage, moisture ingress, and condensation while forming a durable barrier directly bonded to the substrate.

Key performance advantages include:

• Superior adhesion to concrete, ensuring no mechanical fixings are required.
• Zero air permeability, enhancing airtightness and preventing condensation.
• High compressive strength, supporting long-term stability and resilience.
• Fast installation, minimising programme impact.
• Durable and maintenance-free finish, with excellent dimensional stability.

• Pre-installation: Exposed concrete soffits, masked and prepared.
• During installation: Nexseal LE being applied by Duratite operatives using high-pressure proportioning equipment.
• Completed works: Smooth, uniform closed-cell insulation providing seamless thermal protection.

As approved installers of Enverge spray foam insulation systems, Duratite delivers precise, specification-led installations for commercial and industrial environments nationwide. Every project is completed under strict quality assurance protocols, ensuring compliance, performance, and durability.

For technical advice or to specify Nexseal LE closed-cell spray foam, contact:
info@duratite.co.uk
01208 832602