An alternative approach to ventilating challenging sub-floor spaces

In new build homes with precast concrete or timber suspended ground floors, controlling atmospheric moisture in the sub-floor space is normally provided by means of natural ventilators. These include airbricks or grilles of appropriate size and number and are located on opposing external walls to ensure cross ventilation. Attention to detail with sleeper walls and other obstructions in the sub-floor void is also required to ensure that the air can move freely with minimum resistance between external ventilators.
While the provision of such natural ventilation is relatively easy to achieve in new build homes, existing homes often suffer the consequences of inadequate natural ventilation of sub-floor spaces. Ventilators can become blocked over time with dirt and debris or covered when external ground levels are raised through new landscaping or patio coverings. Extensions to homes can also result in natural ventilation of a sub-floor space being negatively impacted. You only have to look at the number of mid terrace homes throughout the UK with rear extensions added with original sub-floor ventilators still visible on the front façade but with none on the rear extension to understand how this can be a problem in many dwellings. There is no way to easily naturally ventilate such a sub-floor.