The challenge
Underground concrete structures sit below ground level where the surrounding earth holds the concrete at a low, stable temperature. When warmer, moist air meets these cold surfaces, water vapour condenses straight onto the soffit and walls, leaving them perpetually damp and the space difficult to use or store anything within.
Bunkers of this kind have irregular cast concrete profiles, restricted access and no natural ventilation path. Traditional board insulation cannot follow the awkward geometry or seal the surface continuously, so cold bridges and gaps remain where moisture keeps forming. The brief was to break that cold-surface condensation cycle reliably.
The ThermoFoam solution
ThermoFoam specified Enverge Nexseal LE closed-cell spray foam, applied directly to the concrete soffit and walls. As it cures, the foam self-bonds to the substrate, forming a continuous insulating layer that follows every contour of the cast structure without fixings, battens or boards.
Because the closed-cell foam raises the internal surface temperature above the dew point and acts as an integral vapour-resistant layer, warm air can no longer reach a cold face to condense on. The seamless application leaves no gaps or cold bridges across the irregular bunker geometry, even in the confined access conditions.
The result
With the concrete surfaces insulated and lifted above the dew point, the persistent condensation that had made the bunker damp and unusable was brought under control. The space became markedly drier and more practical, with the closed-cell system backed by the manufacturer-certified product warranty.
