Home > Companies > BMI Icopal > Monarperm® Breathe All Zones

Monarperm Breathe All Zones is manufactured by laminating a polymer film between two polypropylene fabric layers to form a breathable yet airtight waterproof membrane. The membrane isproduced with a white underside and a blue upper surface printed with overlap guidelines and the product name.

The product may be treated as a vapour permeable membrane and installed without the need for ventilation provided that the roof construction remains air tight and convection free. This may be achieved by using a Monarflex vapour-tight and air-tight membrane (AVCL) at ceiling level.

Features and benefits:

  • Compatible with most materials normally used within roof substructures and finishes.
  • It may be cut and applied using techniques described in the current BS 5534:2014 Slating and tiling for pitched roofs and vertical cladding code of practice. There are no harmful side effects associated with the material. It is not suitable for use with solvent-based timber treatments.
  • The membrane is resistant to ultra-violet (UV) light degradation but is not designed to be left exposed for long periods and must be covered as soon as possible.
  • The product is designed to have a serviceable life equal to the primary roof covering performance.
  • Offers excellent tensile strength characteristics with high puncture and nail tear resistance.
  • CE marked (EN 13859-1 and EN 13859-2).


The product resists the penetration of liquid water when subjected to a hydrostatic head of water of more than five metres and consequently, may be used as temporary weatherproofing prior to the installation of slates or tiles.

The membrane is UV stabilized and may be left uncovered for periods of up to three months, however, the product's exposure to the weather should be considered; especially during wintermonths when the membrane may become damaged by prolonged periods of strong wind and/or persistent heavy rainfall. In these circumstances, the exposure period should be reduced. It is recommended that the membrane is covered as soon as possible

The use of a sacrificial temporary roof covering should, therefore, be considered if prolonged periods of exposure are expected. Due to the nature of installation, a pitched roof underlay is not a complete waterproof barrier and some rain penetration may occur.


Suitable as an underlay for discontinuous roofing (either fully or partially supported) for on pitched roofs over rafters in ventilated and non-ventilated roof constructions. It is used to reduce wind load on slates and tiles and to provide a secondary water-shedding layer against wind-driven rain or snow and has been designed specifically to meet the performance requirements for a pitched roof underlay.

The product is also suitable as an underlay in vertical applications behind weatherboarding and rain screen cladding. Monarflex Eaves Guard is recommended as a suitable product for eaves protection.

Standard product features


  • Upper layer: Blue.
  • Lower layer: White.

Technical characteristics:

  • Surface: Upper: Polypropylene (PP) non-woven UV stable. Middle: Polypropylene (PP) microporous UV stable film. Lower: PP non-woven UV stable.
  • Thickness: 0.67 mm.
  • Weight/ unit area: 135 gm-².
  • Tensile strength to EN 12311-1: 340 N/50 mm (MD). 200 N/50 mm (TD).
  • Elongation to EN 12311-1: 70% (MD). 90% (TD).
  • Resistance to tearing EN 12310-1: 145 N (MD and TD).
  • Dimensional stability to EN 1107-1: <2%.
  • Flexibility at low temperature to EN 1109: ≤-30°C.
  • Reaction to fire (EN 13501-1): Class E.
  • Resistance to water penetration (hydrostatic head) to EN 20811: Mean 5.584.
  • Equivalent air thickness: Sd = 0.02 m.
  • Watertightness to EN 1928 (A) (Class W1): Pass.
  • Wind uplift resistance: Batten spacing <345 mm: 1650 Pa. Zones 1–5. Batten spacing <250 mm: >1650 Pa. Zones 1–5.

- After artificial ageing:

  • Tensile strength to EN 12311-1: 238 N/50 mm (MD). 139 N/50 mm (TD).
  • Elongation to EN 12311-1: 50% (MD). 73% (TD).
  • Watertightness to EN 1928 (A) (Class W1): Pass.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-65-50/323 Vapour permeable sheets

Product specification

An important note about specifying



BMI Icopal


+44 (0)843 224 7400

Product reference

Monarperm® Breathe All Zones

Roll size

[1.0 x 50 m]
[1.5 x 50 m]

Manufacturer details

BMI House,
2 Pitfield,
Kiln Farm,
Milton Keynes,
Buckinghamshire, MK11 3LW
Tel +44 (0)843 224 7400
Fax +44 (0)843 224 7401
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