Wet Sub Floor Voids

Beneath suspended timber floors (within a sub floor void) if the earthen or occasionally concrete oversite is damp or wet, due to high water table levels, then the potential for fungal germination exists to all low level joinery items, it can also cause mould development at ground floor level along with loss of adhesion of wall coverings and an unhealthy environment to the occupants.

Should the existing sub floor ventilation be restricted or poor, then the water vapour from the wet or damp oversite will rise into the occupied living space above and increase the average vapour levels within the rooms.

Whilst increasing the sub floor ventilation to a level to deal with evaporation of water from a wet/damp earthen oversite may assist, the increase is usually such that an adverse effect is brought about, in that the thermal value of the rooms above drop, and so to maintain an acceptable air temperature an increase in heating levels would be required.

Our proven method to deal with this situation is to encapsulate the entire oversite (including the perimeter sub floor walls) with a tough polyethylene membrane, fixed to the sub floor walls using sealed fixing plugs, this obviously will necessitate the levelling of the oversite and removal of any left timber and masonry debris.

A perimeter drainage pipe work system, wrapped in a geo-textile membrane (to reduce pipe blockage) is laid in a shallow trench prior to the encapsulating membrane, the drainage pipework system is terminated in a pre-formed sump chamber containing an automatic submersible pump.

The discharge pipe from the pump is terminated at a suitable ground floor external drainage outlet, the discharge pipe is insulated, if deemed necessary.

Internally to the rooms above the wet/damp oversite various areas of floor boards will need to be removed to facilitate access to the sub floor void, these are replaced/re-fixed upon completion, obviously this would not be required should sufficient working space be present beneath the suspended timber floors.