Concrete Soffit Insulation – Firefly Villa, Mustique

Duratite were appointed to provide specialist consultancy, logistics planning, and onsite spray foam installation for the insulation of a large concrete soffit at Firefly Villa, a newly built luxury residence on the private Caribbean island of Mustique. The project centred on insulating the structural soffit beneath an elevated swimming pool, directly above a high-end gym, spa, and wellness suite.

Despite Mustique’s consistent tropical climate—typically 27°C year-round with minimal variation—the below-grade wellness areas required a robust, belt-and-braces moisture-control strategy. Internal humidity from gym and spa activity, combined with the thermal mass of the concrete soffit, could create micro-temperature differentials sufficient to cause surface condensation.

Fresh Construction approached Duratite for:

• Technical advice on condensation risk
• Specification assistance
• Full international mobilisation of equipment and materials
• Onsite spraying
• Training for local contractors

Project Background

Firefly Villa occupies a dramatic cliff-top plot with panoramic ocean views. The design includes a pool built above a reinforced concrete slab forming the ceiling to several enclosed and mechanically conditioned rooms below.

To avoid condensation risks from:

• humid internal air in gym/spa zones
• concrete’s natural thermal lag
• slight differences between indoor temperatures and external conditions

…Duratite recommended insulating the soffit using Enverge Nexseal LE closed-cell spray foam, forming a seamless thermal and moisture-resistant layer.

Technical Challenges

1. Temperature Differentials & Dew Point Control

Even in warm-humid climates like Mustique, internal spa and gym environments can differ subtly from the temperature of the soffit surface. These micro-differences were enough to justify installing insulation that would:

• raise and stabilise the soffit’s internal surface temperature
• prevent condensation forming on cooler structural elements
• reduce long-term moisture risk
• support controlled atmospheric conditions within the wellness suite

Closed-cell spray foam was chosen for its vapour resistance, monolithic coverage, adhesion, and long-term performance in marine environments

2. Remote Island Mobilisation & Shipping Logistics

Duratite coordinated a full international mobilisation including:

• Shipment of a Graco E10 reactor
• Two full sets of Nexseal LE
• Export from Grays, Essex
• A 3–4 week cargo ship transit to Barbados
• Forward transfer onto Mustique

Because Mustique has limited construction supply availability, every item had to be fully self-contained—including power compatibility, spares, hoses, PPE, tools, and consumables.

3. Challenging Cliffside Access

The villa’s cliff-edge location required careful manoeuvring of:

• 200-litre chemical drums
• spray hoses
• the portable reactor
• all ancillary spray equipment

Working alongside Fresh Construction’s team, Duratite successfully delivered all equipment to the application zone without disruption.