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A high-density polyethylene dimpled sheet which acts as a surface drainage layer in vertical and horizontal applications.


  • Comprises a layer of polypropylene compression-resistant permanent filtration geotextile, laminated to a silver polyethylene (HDPE) drainage sheet with 9 mm height dimples.
  • The vertical drainage system combines high compressive strength with excellent drainage properties.
  • The integrated geotextile mat filters out suspended soil particles and ensures constant water drain-off through the air gap created by the dimple texturing.
  • The silver surface gives the sheet low emissivity as well as enhancing its heat transition resistance.
  • When applied to perimeter insulation boards, the dimpled sheet provides the necessary insulation from contact with the surrounding soil thanks to its plane reverse face.
  • Suitable for vertical gas (methane and Radon) drainage when combined with a classical filtration gravel layer underneath the floor slab. The top apertures of the drainage sheet should be covered with a layer of gravel to enable the gas to escape into the ambient air without difficulty.

Standard product features

Technical data:

  • Conforms to CE requirements and those of BS EN 13252, Certificate No. 0799-CPD-13.
  • Drainage rate: Approximately 3.5 L/s per metre.
  • Compressive strength (transient loading): Approximately 400 kN/m².
  • Compressive strength (permanent loading): Approximately 90 kN/m².
  • Installation depth (maximum): 10 m.
  • Service temperature range: -30°C to +80°C.
  • Delta® dimpled sheets are rot-proof, resisting saline solutions, inorganic acids, alkalines, and polar liquids.
  • They are proof against attack or modification by any of the minerals, humic acids, and bacterial catabolic products that naturally occur in the soil, as well as by bacteria, fungi, and micro-organisms.
  • The response of all sheet types to soil or underground water is completely neutral, nor will they leach any harmful and/ or ecologically doubtful substances.
  • Care should be taken to ensure that they are not permanently exposed to UV radiation.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-65-50/354 Plastics or rubber studded sheets
45-65-50/325 Plastics sheets

Product specification

An important note about specifying



Delta Membrane Systems Ltd


+44 (0)1992 523523

Product reference



[Delta®-Geo-Drain Clip]
Attachment clip for fastening Delta®-MS-Profile.
[Delta®-Stop Pin]
Adhesive pin to facilitate the installation of the dimpled sheet.
[Delta®-MS Plug]
Nylon percussion plug for concrete or masonry.
[Delta®-MS Knopf]
Washer fastening.
Brown moulding cap to protect the upper edge of the sheet.
Moulding cap for application to insulation boards (60–100 mm).
[Delta®-Terraxx-Schraube fixing]
For fastening to perimeter insulation boards.

Manufacturer details

Delta House,
Merlin Way,
North Weald,
Essex, CM16 6HR
Tel +44 (0)1992 523523
Fax +44 (0)1992 523250
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