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Radon sumps


Radon sump installation

The installation of a radon sump is required in all houses either inside or outside high radon areas. For normal floating floor houses, the radon sump will usually be installed under the floor slab in the permeable granular fill material.

A single radon sump can have an influence over an area of approximately 250 m^2^ and for a distance of 15 m from the sump in cases where clean granular fill is used. The effect may be reduced by obstructions beneath the floor slab and the provision of free airways in the rising walls or separate sumps for each compartment may be necessary. A gap equivalent to 12500 mm^2^ per metre run of wall is considered sufficient to create free airways.

Radon sump extraction pipe

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An extraction pipe from a radon sump, image from

A 100-110 mm diameter pipe laid horizontally to the outside of the house from the sump (as shown) is typically used. To avoid drawing in air from the outside, care must be taken to seal all joints in the pipework and seal where the pipe passes through the rising wall. To prevent vermin or rain from penetrating the pipe, cover the pipe either at ground level or at a level that will not cause an obstruction. The pipe may also be extended vertically and capped in the attic space.

Radon sump house location

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Typical location in a single house for a radon sump, image from Radon UK Ltd

It should be noted that a separate sump is required for each house as well as an associated means of extraction.

Proprietary sump installed in hardcore

In the case of a test reading high levels of Radon at any point, the pipe may be extended and a fan fitted. In order to facilitate later activation if necessary and to prevent misuse, ensure that all pipe terminals from the Radon sump are marked clearly to indicate their functions.

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A proprietary sump installed in hardcore, image from WF Developments

Sump with fan connection layout

Detailed below is a typical layout where fan connection must be included.

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Radon sump with fan connection, image from Radon Testing Ireland

Note: “Radon sump connection point” is to be permanently marked on cap.

Ongoing need to check radon levels

Installing radon sumps and membranes in accordance with the measures outlined in TGD C and this appendix do not guarantee that radon will be reduced below the NRL. It is recommended that building owners check the levels of radon when the house is in use and again after remedial action if required.