Sub-Floor Voids, Crawl Spaces, Flooding

Addressing flooded sub-floor voids.

While basements and cellars suffer water penetration more visibly than sub-floor voids, this does not mean to say that below ground (sub-floor voids) are any less prone to water penetration and flooding.

showimageSo what are the implications of a flooded sub-floor?

Walls which reside in standing water are more prone to rising dampness, a process by which the surface tension of water wicks water up through the pores in the building materials (mortar beds typically).  In the event that a functional DPC (Damp Proof Course) is included within the walls at a suitable position, this rising damp should be of no real consequence, so what else is there?

Well, standing water results in air-borne water vapour.  If the floor construction over the sub-floor void is suspended timber, (i.e. timber joists & floorboards), then this may suffer as a result.  More specifically, timber is hygroscopic, in that it will absorb moisture from the air, so high humidity results in high moisture content within the timber, this (if high enough) encouraging decay and loss of structural strength in the long term.  While we do not wish to overly alarm those with such issues, but it is something to be aware of and to address in the event that timbers register excessively high moisture content.

Furthermore, high humidity occurring within the void can transfer to living areas above where suction occurs as a result of warm air rising within the property above.  If you consider that modern properties are often relatively well sealed, with the partial exception of open windows and ventilated sub-floors, rising air escaping through windows at high level within the property can draw air from within the sub-floor to the levels above, this resulting in dampness within floor finishes and a damp environment generally.

As a solution, Trace can install systems to address standing water within a sub-floor void, then isolating the living space over so that formation of a warm dry environment is facilitated.
See our case studies page for example projects.