Monarflex DPM Polyethylene Damp Proof Membranes

Monarflex 1000 Gauge Damp Proof Membrane

Monarflex 1000 Gauge DPM is a loose laid, polyethylene damp proof membrane for horizontal ground supported or suspended slab applications without hydrostatic water pressure. 0.25mm thick and available in 2 x 25 m & 4 x 25 m roll size.

Features & Benefits

  • High elongation at break
  • High resistance to tearing
  • Safe and clean to handle
  • Chemically stable – no volatiles to leach out
  • Joints and seals easily
  • High water vapour resistance

Product Availability

Monarflex 1000 Gauge DPM is a single layer damp proofing membrane manufactured from recycled polyethylene. The membrane is black on the upper and underside surface.

Product Code Description Roll Size
3100402 Monarflex 1000 Gauge 2m x 25m
3100403 Monarflex 1000 Gauge  4m x 25m


Product Data and Performance

Product Data
Material: LDPE
Roll Sizes: 2 x 25 m, 4 x 25 m
Colour: Black
Membrane Thickness: 250 μm
Tensile Strength: MD: 21.6 N/mm2 , CD: 23.6 N/mm2
Elongation: MD: 605% , CD: 684%
Water Vapour Transmission: 0.68 g/m2/day
Water Vapour Resistance: 302 MNsg
Equivalent Air Thickness: Sd = 178 m
Water Tightness: 2kPa


Consideration must be given to the positioning of a radon resisting membrane in relation to thermal insulation.
Installation of Monarflex DPM’s must be in accordance with the recommendations of BS 8102:1990. Additional guidance on the use of damp proof membrane materials is given in BS 8000:Part 4:1989 Workmanship on building sites – Code of practice for waterproofing.

The integrity of the damp proofing membrane must be maintained during installation. 1000 Gauge DPM is one of several Monarflex damp proof membranes available. They have varying degrees of resistance to puncture and tearing. Specific guidance on membrane selection is contained in the Monarflex damp proof membrane product and systems overview brochure. Where damage occurs this must be repaired by covering with a second layer of membrane sealed to the original using Monobond LT or Monarflex MRX.

A surface blinding of soft sand (50mm min. thickness) or geotextile should be used to prevent puncture of the membrane during installation. Sheets must be clean and free from dirt and grease before application.

Installation Details

Ground Bearing Slabs: Monarflex 1000 Gauge DPM may be laid over or under the slab. When laid below slab Monarflex 1000 Gauge DPM should be placed on top of a sand blinding. When placed above slab, the concrete should be dense, smooth and free from any projections which may damage the membrane. Monarflex 1000 Gauge DPM should then be covered with a screed or other suitable protective layer.

Suspended Floors: Monarflex 1000 Gauge DPM should be loose laid over the floor slab, which should be free of debris and any projections which may damage the damp proofing membrane. It should be covered with a screed or other suitable protective layer. Monarflex 1000 Gauge DPM should be installed and fixed in accordance with the manufacturer’s instructions and current Code of Practice.

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

Penetrations: Where service ducts or pipes penetrate the membrane, gas tight joints are sealed using Monobond LT tape, along with top hat units with retention clips. Complex junctions around penetrations such as, steel stanchions and concrete columns may be detailed and sealed by using Easi-Pour self-levelling radon sealant. 

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