The hardcore layer in the floor construction of a building should be clean, dry, well-compacted, and gas permeable (following the compaction process), i.e. suitable material (preferably of single size) should be used which is greater than 10mm and less than 50mm, with no fines (or to an equivalent specification which results in adequate permeability following compaction).
The Easi-Sump radon sump is placed within this hardcore layer (see drawing below).
Each Easi-Sump radon sump should be placed centrally in an area of hardcore. In buildings where there may be many foundation compartments, a short length of 110mm diameter pipe (or a gap of similar size) should be inserted in all internal foundation rising walls, at centres not exceeding 1m and at approximately the same level as the Easi-Sump. This will ensure that the permeability of the hardcore layer remains effective throughout the extent of the building’s foundations (see drawing below).
In the event that a sub-floor radon soil gas control system is activated, it is important that heat producing appliances and the patterns of natural ventilation in interior building spaces should not be affected, or that heat losses be increased. To ensure a necessary degree of separation in the construction of a ground floor, a Radon Resisting Membrane should always be installed by competent personnel.
The Easi-Sump has four spigots, intended for the insertion of 110mm diameter drainage pipes (see drawing to right). Typically, one of these pipes should be laid, in accordance with standard drainage pipe installation procedures, to connect with the Easi-Sump Cap-Link, which is located just outside the external wall of the building. The other blanked-off spigots should be opened, as required, to accept pipe inserts coming from another part of the building’s foundation, and/or another Easi-Sump. For reasons of condensation control, falls in pipework should be towards the Easi-Sump.
Depending on the quality of ground floor specification, whether or not it is accurately followed on site, the quality of workmanship, and level of technical control during this critical phase of construction, the effective pressure field of the Easi-Sump radon sump may extend well beyond an area of 250m², or fall below 50m².
As a general rule:
- with Category A Construction Execution, allow for one Easi-Sump to service an area not greater than 200m²;
- with Category B Construction Execution, allow for one Easi-Sump to service an area not greater than 100m²;
- with Category C Construction Execution, allow for one Easi-Sump to service an area not greater than 50m².
Extra Easi-Sumps may be added, or interlinked, to a subfloor network in order to service larger areas.