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NewSeal 408 DeckDrain

  1. Efficient Drainage Solution: Double cuspated membrane with a polypropylene geotextile filter layer and water impermeable HDPE core provides efficient drainage for decks, balconies, and flat roofs.
  2. Dual-Layer Design: Unique double cuspated design offers two layers of drainage, ensuring effective water management in various applications.
  3. Versatile Applications: Ideal for use above waterproofing membranes in areas with block paving, flooring slabs, soil-filled planters, or intensive green roofs. Also suitable for vertical drainage in professionally designed basement waterproofing systems.

Double cuspated, deck and flat roof drainage membrane, that incorporates a polypropylene geotextile filter layer, bonded to a water impermeable HDPE (High Density Polyethylene) core. The double cuspated design provides two layers of drainage.


  • Key Benefits
  • Typical Applications
  • Suitable Substrate
  • Technical Data
  • Key Benefits

    Key Benefits

    • Provides a clear and clean drainage path for surface water to roof drainage outlets.
    • Double cuspated (drainage studs to the upper and lower surfaces) design provides a clear and clean drainage path above the deck waterproofing membrane, to ensure that water cannot be trapped above the deck membrane, as can be the case with single cuspated deck drainage membranes.
    • Suspended soil particles (fines) are filtered out by the geotextile layer.
    • Quick and easy to install.

    Typical Applications

    Typical Applications

    As the drainage layer above a deck, balcony or flat roof waterproofing membrane, particularly where:

    • Block paving or flooring slabs are bedded on sand as the surface finish.
    • Soil filled planters are included to the deck or flat roof.
    • An Intensive Green Roof is planted to the deck or flat roof.

    Also suitable for use as a vertical drainage layer when used as part of a professionally designed and installed externally applied basement waterproofing system.

    Suitable Substrate

    Suitable Substrate

    Directly above primary deck or roof waterproofing membrane.

    Technical Data

    Technical Data

    Installed Performance Result
    Compressive strength – Temporary loading 280 kPa
    Compressive strength – Permanent loading 10 kPa
    Water vapour diffusion resistance – Sd value >604m
    Water vapour diffusion resistance – µ value >1208000µ
    Water vapour diffusion resistance >3020 MNs/g
    Tensile strength (Machine direction) 13.6k N/m2
    Tensile strength (Cross direction) 14.7k N/m2
    Chemical resistance – Excellent 100%
    Oxidation resistance – Excellent 100%

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    Speak to our friendly, expert team

    Our staff are able to provide guidance for projects of all sizes, whether you require some general advice about damp or waterproofing, or support with technical drawings and specifications.


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      We will be closing between Christmas and New Year, with the last day of operations being Friday 20th December. Last orders for delivery before Christmas therefore need to be placed by 2pm on Thursday 19th December, with final deliveries on Friday 20th December. After this, no deliveries will be possible until January 2025. The Newton branches in Tonbridge and Leeds will reopen in the New Year on Thursday 2nd January 2025.