Icopal Monarperm Breathe All Zones Breather Membrane

Monarperm Breathe All Zones

Monarperm Breathe All Zones utilises the latest technology to produce a durable LR pitched roof breather membrane capable of offering improved dependable performance and the strength to meet all wind uplift conditions in a single product.

Monarperm Breathe membranes are suitable for installation fully supported directly over insulation boards or draped unsupported over rafters and will be virtually unaffected by normal conditions within a pitched roof space.

Features & Benefits

  • ’Unrestricted’ use for wind uplift in UK & Ireland
  • Helps to avoid condensation risk in accordance with BS 5250
  • Highly Vapour Permeable
  • Completely Watertight & Airtight
  • Strong, Tough & Durable
  • BBA Certified
  • NHBC compliant.
  • Construction of Monarperm Breathe Membranes

    Monarperm Breathe membranes consist of a highly vapour open microporous film thermally bonded between two outer layers of spunbonded polypropylene. The outer layer forms an exceptional external wind and waterproof layer the central microporous film acts like a one way valve allowing vapour to escape whilst preventing water penetration through the membrane. The inner white surface protects against abrasion and provides a high level of light reflectance.



    Vapour Open

    Monarperm Breathe Membranes allow water vapour arising from the occupied space to diffuse safely to the atmosphere, preventing the buildup of high concentrations of water vapour and reducing the risk of harmful condensation.


    Monarperm Breath Membranes will provide protection against wind driven rain or snow which may penetrate the tiles or slates tracking any water safely down to the gutters and away from the construction

  • Zone Suitability Map - Compliance with BS5534:2014 annex A

    The code of practice BS5534:2014 annex A requires that pitched roof underlays are assessed with regard to resisting the effects of wind uplift acting on the membrane.

    The code requires that manufacturers test their products at defined batten centres from 345mm for most interlocking tiles down to 250mm which covers most double lap and interlocking slates and against various levels of wind speed. This is to avoid “ballooning” which can impact upon the slates or tiles causing them to dislodge.

    Subject to the independent testing by official bodies, membranes are provided with a zonal classification indicating which particular areas of the Country they may be used.

    Monarperm Breathe membranes have been tested in accordance with BS5534 annexe A by the BRE and independently assessed and approved by the BBA.

    Zonal Suitability - Monarperm Breathe All Zones (no tape required)

    Up to 345mm batten gauge
    Up to 345mm batten gauge
    Up to 345mm batten gauge
    Up to 345mm batten gauge
    Up to 345mm batten gauge

    The map above and tables below provide the wind uplift resistance data and the Zonal classification for Monarperm Breathe All Zone Membranes.

    Rafter Spacing 600mm Monarperm Breathe All Zones
    Batten Spacing Pa Zones
    < 345mm 1650 1 - 5
    < 250mm >1650 1 - 5


    The above values are for overlaps made under a batten without the use of tape 

    Wind Zone 1 2 3 4 5
    Design Wind Pressure Pa 1600 1330 1150 975  820


    Note: Values stated in the above table relate to the required design pressures using batten centres of 345mm and where a well - sealed ceiling is installed, ridge height is not greater than 15m, roof pitch is between 12.5 & 70 degrees, site altitude is not greater than 100m and no significant topography is present.

    In other conditions the following values must be observed.

    • 1900 N/m² when no ceiling or no well - sealed ceiling is present
    • 2350 N/m² when no ceiling or no well-sealed ceiling is present and a permanent dominant opening is present on an external face of the building.

    As stated in BS5534:2014 membranes tested and suitable for use in Zone 1 at maximum 250mm batten spacing are suitable for use in all wind zones when fully supported by sarking boards, Plywood or Thermal Insulation.

  • Product Availability


    Product Code Description Roll Size Roll Weight
    3102819 Monarperm Breathe All Zones 1m x 50m 7kg
    3102818 Monarperm Breathe All Zones 1.5m x 50m 10.0kg



    Rolls are supplied individually packaged in a polythene outer bag which carries the Product description CE marking and zonal classification.

    Rolls per pallet: 30


    Monarperm Breathe membranes should be stored on a clean and level surface, kept dry and adequately protected from damage.

  • Product Data and Performance


    Product Data:
    Composition: A three layer composite structure manufactured from a highly vapour open film bonded between two layers of non woven micro porous polypropylene.
    Colour: Blue upper surface
    White lower surface
    Rolls per pallet: 30

    Physical Properties


    Weight: 135 g/m² +/- 10%
    Thickness: 0.67mm  
    Water Vapour Transmission (Sd),m: 0.02 +0.03/-0.01
    Watertightness class: W1  
    Hydrostatic head (m): 5.85  
    Tensile Strength (N/50mm) unaged: 340 MD, 200 TD +40/-40
    Nail Tear Strength (N): 145 MD, 145 TD +45/-45
    Elongation (%) unaged: 70 MD, 90 TD +15/-20
    Low Temperature Flexibility deg C -30  
    Wind Uplift: 1.65 kPa at 345 mm batten gauge and 600mm rafter centres


  • Installation

    Install Monarperm Breathe membranes in accordance with the following guidelines:

    • BS5534:2014, BS8000 part 6:2013, BS5250:2011 NHBC guidelines and Icopal fixing instructions.
    • Handle & Fix the membrane with care to ensure no tears or punctures prior to covering with the primary tiles or slates.
    • Counter battens or tile battens should be installed as soon as possible to fully secure the membrane and prevent unnecessary tearing by the wind action.
    • Cover the membrane as soon as possible with the outer covering of slates or tiles, Monarperm Breathe membranes will provide temporary protection but cannot be considered totally watertight.
    • When installing unsupported ie over open rafters ensure an adequate drape of 10 -15mm to ensure free draining of any water effectively to the eaves. Do not pull the membrane taught so that it is in contact with the tile batten as this will prevent the flow of water. Install by unrolling across the roof parallel to the eaves, working from eaves to ridge.
    • When joining rolls ensure a minimum 100mm overlap and secure with Monobond tape. Always join rolls over a rafter.


    Roof Pitch Horizontal Lap Vertical Lap*
    Partially Supported Fully Supported
    12.5° - 14° 225mm 150mm 100mm
    15° 150mm 100mm 100mm
    > 34° 100mm 75mm 100mm

    * form vertical laps over rafters


    • Always use a separate Icopal Eaves Guard at gutters to provide additional protection from UV exposure.
    • Do not lay any vapour permeable membrane over undried timber preservatives, water or solvent based.
    • Terminate the underlay at abutments by turning up 100mm behind securely fixed cover flashings and seal to the structure using Monobond tape.
    • Reinforcing strips of membrane should be installed at hips, valleys and ridges
    • Exposed fixing of the membrane should be avoided.
    • Use large head clout nails and avoid the use of staples.
    • Fixing should be made into the rafter along the top edge of the membrane and covered with the overlap of the adjacent sheet.
    • Fix the outer covering of slates or tiles in accordance with the manufacturers specific instructions and ensure the fixing specification complies with the relevant code of practice.
    • Ensure that any provision for ventilation complies with BS5250:2011 and NHBC guidelines section 7.2.S11.
    • Ensure the underlay does not obstruct any ventilation paths.
    • When detailing around services such as skylights and chimneys dress the underlay to the upstand min 100mm and seal with Monobond tape before covering with the appropriate counterflashing.


    Health and Safety

    Construction or replacement of a pitched roof means working at height and as such personal safety and prevention against a fall must be considered a priority. When working on a roof ensure all necessary safety precautions are in place and follow safe working practices. Although the Icopal Monarperm and MonarTile range are strong it should not be walked on or used as a working platform.

Contact Icopal 0161 8654444

Find Local Support

To discuss your project in more detail please contact
Your Local Area Manager


Technical Support


0330 123 4585

Email: technical.uk@bmigroup.com


Sales Enquiries & Orders


0843 224 7400


0843 224 7401

Email: sales.admin@bmigroup.com

Latest News

A new faster, safer, stronger and lighter metal tile solution from BMI


Band of Builders and BMI team up for community project


The search is on for the BMI Apprentice of the Year 2020


Oscar heads for the limelight


BMI helps Children in Need keep young people safe


Everyone's a winner - that's the truth!


This site uses cookies in accordance with our Website Privacy Policy. By continuing to browse the site you are agreeing to our use of cookies. To browse without the use of cookies, you can opt-out as explained in our Website Privacy Policy or adjust your cookie settings for your browser

Icopal: We Protect Your Building