Drying of a flooded basement in South-West London

The water was trapped inside the floor construction

The drying programme ran for five weeks. The trapped moisture within the floor construction was successfully dried, while the pressure-drying approach avoided the need for a more extensive strip-out of the basement floor and helped preserve the cavity drainage membrane.

For this property, the result came from treating the basement as a layered construction rather than simply a wet room. By directing dry air into the areas where moisture was being retained, the drying strategy addressed the part of the flood damage that was not visible from the surface.

Mapping the floor before drilling

A pressure-drying system built around the floor

Remote monitoring kept the drying programme moving

Five weeks to dry the trapped moisture

Expert insight: Drying the construction, not just the room

The main challenge was not simply the amount of water that had entered the basement, but where that moisture had travelled. The floor build-up contained multiple layers, and investigation identified high moisture levels trapped between the cavity drainage membrane and insulation.

Humidity probes were used at different depths and left in place for 24 hours to establish conditions within the floor. Those readings confirmed that a conventional room-drying approach alone would not be enough; the drying system needed to move dry air into the affected floor layers.

Before the pressure-drying system could be installed, the team needed to understand what lay beneath the finished surface. Thermal imaging and pipe detection were used to identify safe drilling locations, while the wet underfloor heating system was drained before the drying installation progressed.

The basement was also cleared so the affected areas could be accessed properly. Where necessary, thermal insulation was removed manually with care taken around the cavity drainage membrane.

Once the preparation was complete, 25mm access holes were drilled at selected locations and injection-drying systems were installed to deliver dry air into the floor build-up.

The drying environment combined injection equipment with desiccant and condensing dehumidification. Rather than relying on one method, the system was designed to address both moisture held within the construction and moisture released into the basement air as drying progressed.

Remote monitoring was installed to track drying conditions as the programme progressed. This allowed the performance of the drying environment to be followed without relying solely on repeated site visits and supported adjustments to the equipment as conditions changed.