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Radon Membranes

Radon Ireland is a professional installer of Radon/Methane Barrier who will provide a certificate to confirm that the job is completed in accordance with approved guidelines. Gas can enter the building through the smallest gap in the radon barrier, therefore thorough installation of high quality and fully certified Radon Barrier is essential.

Building regulations introduced in 1997 state that measures should be taken to protect the building from the ingress of radon gas into the property. This requires a fully sealed membrane of low permeability to be installed over the entire footprint of the building upon construction.

All Membranes used carry full IAB-CE Certification

We carry the following membranes as standard:

  • Monarflex RMB400 is a high quality loose-laid reinforced radon barrier membrane that offers high resistance to radon gas and has excellent tensile and tear strength
  • Monarflex RMB350 is a high quality loose-laid radon resisting membrane made from blends of virgin low density polyethylene (LDPE).
  • Monarflex Necoseal is a virgin polyethylene membrane. When used as part of the Necoflex RAM System it provides an effective radon, air-tightness and moisture seal in the foundations of a new building. Necoseal should be used in conjunction with Easi-Load Radon DPC at all masonry walls.
  • Radon Block™ is the new leading high performance radon blocking barrier membrane. When properly installed, Radon Block™ resists gas and moisture migration into the building envelope, providing superior protection from toxic and harmful chemicals.

Why use a Radon Membrane?

Naturally occurring radioactive radon gas is a breakdown product of radioactive uranium in the Earth's crust. It is a known carcinogen and poses a chronic toxicity hazard to man.

Radon is responsible for some avoidable 440 deaths a year from lung cancer in Ireland.

Geological studies and maps can only provide a rough guide to heavy pockets of the gas and never an accurate figure on the radon level in any one specific home or workplace.

Because radon enters a building from the ground on which it is built, the most effective method of reducing indoor levels, is by preventing it entering the building in the first place. This is done by means of installing a radon barrier correctly by a specialist radon contractor.

Recently published research indicates that a significant health risk exists at levels of radon lower than the current action level and the need for effective and improved protection is increasingly important.

What is a Radon Barrier?

This is a fully sealed very low gas permeability barrier (sometimes referred to as a membrane) placed over the entire footprint of the building at the time of construction. In some cases it can be provided in lieu of the damp-proof membrane. It is important that the requirements of the radon barrier are considered during design.

The requirement of a radon barrier is to prevent any radon gas entering into a property. It follows therefore that the material used, must be adequate for the task and fulfill several criteria:

  1. Easily packed and protected during manufacture, storage and transport,
  2. Sufficiently robust and impervious to the gas,
  3. Sufficiently strong to withstand the installation process and following trades until covered, and
  4. Capable after a skilled installation of providing a complete barrier to the entry of radon gas.

The Installation of Radon Membrane

The Membrane

The Membrane to radon gas will be a proprietary barrier which is preferred to ordinary polythene, as it is normally of a superior quality. In most cases it is reinforced for additional strength and designed for the purpose. Whatever the material or construction the barrier must cover the whole footprint of the building including any external or internal cavities.


It is important that the requirements of the radon barrier are considered at the design and layout stages. Care should be taken at the design stage to ensure that a structural slip plane does not occur.

Care must be taken to ensure that the barrier is laid on well-blinded hardcore, suitable Geotextile, or cleaned and swept suspended floor that is free from projections, indentations, irregular or sharp finishes and should be inspected for damage prior to covering with slab or screed. Any damage should be repaired with barrier ensuring a 150mm lap. Where strips of barrier are incorporated into the external and internal walls at commencement, they must be suitably protected for the duration of the build until the main carpet of the barrier is installed. All laps and joints should for preference be welded or as a minimum requirement sealed with butyl jointing tape, (normally 50mm wide or as specified by the manufacturer) and not adhesive tape, The barrier should be dry and clean before sealing. All penetration for services and drains should be sealed using a preformed top hat, again welded for preference, or sealed to the barrier with butyl tape.

Post Installation

Even small perforations in a barrier can in certain areas result in high levels of radon penetration and the integrity of a perfectly laid barrier can be compromised by subsequent actions.

Consideration must be given after installation to:

  1. Subsequent building modifications or the addition of extensions.
  2. Recent studies have shown following radon tests in “new-build” homes, that a large number of new properties may have radon problems contrary to the aims of the legislation. The source of many such problems is probably due to faulty or incorrectly laid barriers, or, to finishing, plumbing, wiring and other operations that have damaged the integrity of the barrier work.

The following Minimum performance levels for Barrier materials are an excerpt from Technical Guidance Document C, September 2004. Published by The Stationary Office – Dublin

Minimum performance levels for Low Density Polyethylene (LDPE) Membranes.

Certification of materials used for radon membranes should demonstrate compliance with the following parameters.

Parameter Test Performance Level of LDPE
Radon Permeability Laboratory Test with Radon Gas – Rn 222 12X10-12m2/s
Tensile Strength I.S. EN 12311-2:2000
I.S. EN ISO 527-3
MD > 12Mpa
CD > 12Mpa
Elongation I.S. EN 12311-2:2000
I.S. EN ISO 527-3
> or =100% (at break)
Un-reinforced LDPE > or =12% (at break)
Reinforced LDPE
Tear Resistance I.S. EN 12310-2:2000 >100N
Moisture Vapour Resistance BS 3177 >50MNs/g
Low Temperature Flexibility I.S. EN 495-5:2000 No cracking at –250 C

Reproduced by courtesy of Department of the Environment, Heritage and Local Government – Republic of Ireland.