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RIW Double Drain - Water Management System


Externally applied water management system, used to protect and drain the basement or structure.

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  • Used to protect and drain the basement or structure.
  • Not to be used as a primary membrane.


A cold applied impermeable high density polyethylene profiled sheet incorporating a permeable geotextile filter fabric designed to prevent ground water reaching a structure and enhance the performance of the waterproof membranes.

The product can be used in conjunction with a primary waterproofing system or on its own to isolate the structure from the surrounding soil and relieve hydrostatic pressure by promoting the flow of ground water away from the face of the structure to land drainage. CE marked, the system can also be used to provide protection to a primary waterproofing system against backfilling and mechanical damage.

Features and benefits:

  • Prevents ground water reaching structure.
  • Isolates structure from surrounding earth.
  • Eliminates necessity for granular backfill.
  • High drainage capacity.
  • High impact resistance, providing protection to the primary membrane.

Fixing to vertical/ sloping surfaces:

  • RIW Adhesive Tape at 2000 mm maximum centres, when used against the primary membrane.
  • RIW X Cramps at 250 mm maximum centres, along the top edge only, when fixed directly to wall surface.


70 mm overlaps, with geotextile fabric-patch bonded with bonding tape.

Deformation under long term loading:

25% maximum.

General information




High density polyethylene (HDPE)


RIW Limited’s waterproofing products will, subject to normal service conditions, provide an effective barrier to the transmission of liquid water and water vapour for the life of the building in which they are incorporated., The products must be installed in accordance with RIW written instructions, and following installation must not be subjected to any damage or long-term UV exposure.


2 x 20 m


Pr_25_57_51_74 Rubber studded sheetsPrimary


J40/295 Geocomposite studded cavity drainage/ venting membrane

Specification data - Rubber studded sheets



Studded layer

High-density polyethylene (HDPE).

Stud height

8 mm.



Performance characteristics


Flow rate

2.3 L/s (maximum).

Bonding tape

RIW Adhesive Tape.

RIW Adhesive Tape is a 150 mm double sided tape for adhering the RIW Double Drain to the primary membrane, and for re-adhering the geotextile fabric at overlaps.

Top edge protection

RIW Top Edging Strip.

RIW Top Edging Strip is a medium density profiled polyethylene sheet which protects the top edge of the RIW Double Drain and prevents clogging.

Digital objects

Platform Compatible Version Certified to

Revit 2016





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