Icopal Monarflex RMB400 - Radon Barrier Membrane

Monarflex RMB400 - Radon Barrier Membrane

Monarflex® RMB400 is part of Icopal’s Monarflex® radon control system and is used to protect buildings from the ingress of radon gas. It is a loose-laid barrier membrane and may be installed below or above a ground-bearing slab, or on top of a suspended concrete floor. Monarflex® RMB 400 is also suitable for use as a damp- proof membrane.

Features & Benefits

  • High tensile strength
  • High resistance to tearing.
  • Designed to withstand foot traffic
  • Use for housing or commercial build
  • Compatible with all forms of DPC’s
  • Joints and seals easily
  • High water vapour resistance
  • Radon gas resistant

Product Availability

Monarflex® RMB 400 is manufactured from three layers of virgin low-density polyethylene (LDPE) with a 9 x 12mm multi-filament polyester (1670 dtex) reinforcing grid between to give high strength and tear resistance. The radon barrier membrane is coloured red on both sides. RMB 400 Can be used in conjunction with Easi-Load Radon DPC through masonry walls.

Product Code Description Roll Size Weight
3002978 Monarflex RMB400 2m x 25m 21kg
3002979 Monarflex RMB400 4m x 25m 42KG


Product Data and Performance

Product Data
Width: 2.0m, 4.0m
Length: 25m
Colour: Red
Weight/unit area: 409g/m-2
Membrane Thickness: 0.4mm
Water Vapour Resistance 1024 MN·s·g-1
Equivalent air thickness: Sd = 176 m

Resistance To Puncture: The products have a high resistance to puncture. On smooth or blinded surfaces they will not be damaged by normal foot or site traffic (eg wheelbarrows) but care must be taken to avoid damage during installation, particularly when handling building materials and equipment over the surface and when placing concrete or screeds, since they can be punctured by sharp objects.

Resistance To Moisture: The membranes and the methods of jointing provide an effective barrier to the passage of moisture from the ground and will enable a floor to comply with the requirements of the national Building Regulations, if installed in accordance with the manufacturer’s instructions. 

Durability: Monarflex® RMB 400 radon barrier membrane is manufactured to last the lifetime of the construction provided it is correctly installed and not damaged by subsequent building operations.

Compatibility: Monarflex® RMB 400 membranes are fully compatible with the range of Icopal damp-proof courses and membranes. 

Installation Details

Ground Bearing Slabs: Monarflex® RMB 400 may be laid over or under the concrete slab. When laid below slab Monarflex® RMB 400 should be placed on top of a gas permeable layer, such as hardcore blinded with well compacted sand. When placed above slab, the surface should be smooth and free from any projections which may damage the membrane. Monarflex® RMB 400 should then be covered with a screed or other suitable protective layer.

Suspended Floors: Monarflex® RMB 400 should be laid over the floor slab and then covered with a screed or other suitable protective layer.

Monarflex® RMB 400 should be installed and fixed in accordance with the manufacturer’s instructions.

Application: Where service ducts or pipes penetrate the membrane, joints are effected using Monobond sealant tape and top hat units with retention clips. Complex junctions around penetrations such as, steel stanchions and concrete columns may be detailed and sealed by using a fully bonded membrane such as Xtra-Load® GRM or Monarseal MRX self adhesive, bituminous membranes with an overlap of 150mm on each surface.

Detail work should be completed first to limit foot traffic across the membrane. Once completed, Monarflex® RMB 400 may be laid and overlapped and sealed with Monobond sealant tape. The radon barrier membrane should be rolled down firmly to ensure an effective bond and seal.

Steel, concrete and masonry surfaces should be primed with Xtra-Seal® QD Bitumen Primer prior to the application of the fully bonded membrane.

Jointing: To form joints between adjacent sheets of Monarflex® RMB 400 lap the membrane by a minimum of 150mm and seal with a strip of 30 mm wide Monobond tape.

Repair: Any damage must be repaired using patches of Monarflex® RMB 400, extending a minimum 150mm from the puncture and continuously sealed with Monobond tape. 

    Contact Icopal 0161 8654444

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