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DELTA PT - Cavity Drain Membrane System (Type C)

Verified by manufacturer 2 months ago

Delta Membrane Systems Ltd Third party certifications:
  • BBA Agrément Certificate

    BBA Agrément Certificate

    Certificate type

A dimpled waterproof membrane with a mesh face, providing a key for plaster, render or dab fixed board finish.

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  • Mesh is welded to the front face of the membrane to allow plasters and renders to be applied.
  • Studs isolate the wall from the new plaster and allow ventilation of the wall for permanent dampness control.
  • Ventilation is achieved with the use of an external air vent or with the use of Delta-PT Profiles fixed at the upper and lower edges of the wall. The profile has ventilation slots provided.
  • Delta-PT can be used as part of a sealed waterproofing application, on walls, vaults, and archways where a plastered or rendered finish is required or when a specific key is needed. It can also be used externally as a waterproof support for rendered finishes.
  • All joints and fixings must be sealed using Delta sealants.
  • Sheets must be fixed along all edges and generally at not more than 250 mm vertical and horizontal staggered centres using Delta-PT Fixing Plugs and Delta Sealant or grommet. Alternatively, use the Delta-Qwik-Seal Plug. When used externally, fixing centres must be closed up to 150 mm.


A dimpled membrane with a mesh face, providing a key for plaster, render or dab fixed plasterboard.

Features and benefits:

  • A high performance polyethylene membrane for use on damp and/ or contaminated walls, above and below ground, vaults and basements.
  • Delta-PT is extruded into a series of studs to create a continuous air gap behind the waterproof membrane.
  • Plastering: The membrane should be plastered with either 'Whitewall' plaster or Carlite Bonding.
  • External rendering:
  • Where the membrane is to be used externally it must be rendered with a cement-lime-sand (1:1:6) render applied in three coats to a total thickness of 20 mm.
  • Due to the difference in thermal characteristics between Delta-PT and the render, expansion joints through the render to the membrane must be trowelled in along each lap joint to reduce the possibility of cracking. These joints must be filled with a suitable flexible polymer-based sealant.
  • Alternatively, a polymer/fibre modified render can be used and should be applied in two coats. This render is polymer/ fibre modified, and eliminates the need for extensive expansion joints, other than what is required to meet the Building Regulations.
  • A 5 mm ventilation gap at the top, and at least 10 mm at the bottom should be left to assist the ventilation of the air-gap behind the Delta-PT membrane. Delta-PT profile is secured to the membrane and substrate to maintain these gaps.
  • Dry lining:
  • A Bonding plaster to BS 1191-2, Type A3, is applied in vertical strips over the fixing centres and in bands along the top and bottom of the membrane. The plaster dabs are applied to a minimum thickness of 8 mm, and should cover a minimum of 50% of the membrane.
  • Gypsum plasterboard to BS 1230-1,or similar drylining boards covered by Agrément Certificate, are pressed onto the plaster dabs and jointed in the usual manner.
  • Decoration: Once the plastered, dry-lined or rendered surface has dried, the surface can be painted or wallpapered using traditional methods and materials.

General information




High density polyethylene (HDPE)


20000 mm


2000 mm


8 mm

Warranty description

30 year


Pr_20_85_46_21 Damp-proof lathingsPrimary


M20/624 Damp proof lathing

M20/85 Damp proof lathing

Specification data - Damp-proof lathings

Third party certification

To BBA Agrément Certificate.


Polyethylene (HDPE).

Stud size

1500 mm.

2000 mm.

Manufacturer guidance

Roll size.


70 kN/m².

Guidance for specification option:



5 L/s.

Guidance for specification option:

Approximately per metre.


0.5 x 8 mm.

Guidance for specification option:

Thickness x height.

Sustainability data

Contains Red List materials


Country of product manufacture




Recycled content

As defined in clause 7.8 of BS EN ISO 14021

0 %

BIM objects


NBS BIM Object Standard

This BIM object has been authored to meet the requirements of the NBS BIM Object Standard.

Find out more about the NBS BIM Object Standard.

Platform Compatible Version






Revit 2016






Third party certifications

BBA Agrément Certificate

BBA Agrément Certificate

3742ps2i5 - BBA Certificate Delta MS20

Case studies

Lightwell Waterproofing Solutions

Lightwell Waterproofing Solutions

Damp Remedial Solutions

Damp Remedial Solutions