Delta MS20 - Cavity Drain Floor Membrane (20mm Stud)

Delta MS20 - Cavity Drain Floor Membrane (20mm Stud)

Delta Membranes | Basement Waterproof Membranes

Delta MS20 is a High Drainage, BBA Approved Cavity Drain Floor Membrane with superior drainage capacity and compressive strength, manufactured from High Density Polyethylene (HDPE).

Delta MS20 is suitable for use as a high performance water control and management system in building and civil engineering construction. A superior solution for waterproofing basement floors.

  Delta MS20 is supported by BBA Certification Certificate Number 00/3742.

Available in (W) 2.0M x (L) 10M (20M²) and (W) 2.0M x (L) 20M (40M²) Rolls.


Delta MS20 - Cavity Drain Floor Membrane

Delta MS20 is a High Drainage, Cavity Drain Floor Membrane with superior drainage capacity and compressive strength, manufactured from High Density Polyethylene (HDPE).

Delta MS20 is suitable for use as a high performance water control and management system in building and civil engineering construction. A superior solution for waterproofing basement floors.

With its 20mm deep stud profile, Delta MS20 is used as a high drainage capacity floor membrane and is generally specified where it is anticipated that there may be a risk of severe water penetration.

Delta MS20 is suitable for Type C waterproofing while delivering a Grade 3 environment to BS8102:2009.

Delta MS20 has a life expectancy of at least the design life of the building. It is inert and, therefore, non-polluting to drinking water, highly resistant to water, alkalies, saline solutions and organic acids, and not affected by minerals and hydro-carbons. It is also impervious to root penetration, is rot-proof, and resistant to bacteria, fungi and other small organisms.

Benefits & Features:

  • Type C Drained Protection in accordance with BS 8102:2009

  • BBA Approved

  • Suitable for higher volumes of water penetration

  • A reversible system, which will minimize damage to historical or heritage structures

  • Virgin High Density Polyethylene Studded / Moulded Sheet (HDPE)

  • An effective barrier to the transmission of salts, liquid water and water vapour

  • Resistant to Chemicals, Root Penetration, rot proof, neutral towards drinking water

  • Suitable for Flood Resilience

  • Resistant to Carbon Dioxide, Radon and Methane

  • Can be used as a 'Cavity Former for many types of new construction.

  • Suitable for use above and below ground, in new construction or in existing buildings over a contaminated or damp background.

Typical Applications:

Delta MS20 is primarily used as an underfloor Cavity Drain Waterproofing / Damp Proofing Membrane.

Delta MS20 can support a screed or flooring, in the following situations:

  • On damp floors in underground situations subject to high groundwater levels, and perennial moisture.

  • In conjunction with a Remedial DPC System where the walls and floors have a high salt content, and/or it is necessary to complete the installation immediately without allowing a period for initial drying.

  • Over floors which have a friable or painted surface, are contaminated (i.e with Oil or Mould), or have a high salt content.

  • As a Waterproofing Membrane in areas subject to vibration.


  • NBS Specification J40 (Clause 290) Flexible Sheet Tanking / Damp Proofing.

  • BS 8102:2009 Type C Drained Protection

Technical Data:

Membrane Material High Density Polyethylene (HDPE)
Membrane Thickness 1mm
Stud Height 20mm
Air Volume Between Studs 14L/M²
Compressive Strength 150kN/M²
Temperature Resistance
-30°C to +80°C
Drainage Capacity 10L/s M
600 L/min M
3,600 L/Hr M
R Value 0.18 M² K/W
Drainage Capacity Per Metre 1.25 L/sec M²
Temperature Resistance -30°C to +80°C
Resistance to Fire (BS EN 13501-1) Class E



Delta MS20 should only be used on floors. Before the system is installed, the area must be assessed to determine what preparation is required:

All timber and other organic material must be removed to prevent risk of fungal or bacterial growth behind the System. If evidence of rot exists, this must be dealt with by a specialist contractor prior to installation of the system (See our Woodworm & Dry Rot Control Products).

Brush the floor clean and remove any sharp protrusions. Fill all non-structural cracks above 1mm wide, all structural cracks should be repaired or treated.

New concrete should be treated with Platinum Lime Inhibitor which prevents free lime from the curing concrete being drawn out by ingressing water.

Drainage Requirements:

When used in a full or part earth-retaining situation, the membrane system must be drained. To comply with BS 8102:2009, you must assume that the structure will be subjected to water ingress at some time.

Methods Of Drainage:

The drainage must effectively remove all water from below the membrane and take the water to a point of discharge such as a Sump Chamber or a form of safe natural

drainage. Standing water can block the membrane with silt or lime scale so it is important for water to flow uninterrupted to the drainage point.

Delta Drainage Channel

Delta Channel is placed at the wall / floor junction and collects water from behind the wall membrane and receives water at the wall / floor junction.

It is a designed method of removing water as it can interface with sump chambers, gullies, waste pipes etc.

It can also be maintainable by inserting Delta Jetting Eyes into the system.

Installation Method:

It is very rare for water to pass through a solid concrete slab or concrete raft, but where the slab or raft is of questionable quality it is possible for water to pass through cracks in a poorly constructed floor. If the quality of the slab is questionable, Delta MS20 should be used as the floor membrane.

Starting at one side of the room, unroll the membrane with the studs down and cut to fit the room as one would a carpet. The next membrane width is rolled out so that the flanged edge overlaps onto the edge of the previous roll of membrane. Clean both edges.

Delta Tape is then applied to the high flat area between the first two studs at the edge of the previous roll of membrane with the backing paper still intact.

Check the two widths for alignment, with the flange covering the backing paper.

Starting from the end of the joint, remove the backing paper and press down on the joint sealing the two sections together. This process is repeated until all areas are covered. Seal the Delta MS20 Membrane to the up-stand of the Delta Channel with Delta Corner Strip.

Where the floor membrane is required to be jointed to horizontal DPC’s through internal and external walls, these joints should be sealed with Delta Tape. Ensure both surfaces are clean and dry before attempting to make these joints.

If there are any services up through the floor, the membrane can be cut and trimmed around them, and the gap filled and sealed using a high quality MS or SMX Polymer Adhesive.

If necessary, a patch of membrane or Plain DPC is laid over and sealed to the service with Delta Rope, and around its perimeter with Delta Tape.

It should be noted that protrusions through the floor slab/raft should be avoided wherever possible as they create weaknesses that allow unnecessary water ingress.

The specified floor finish can now be laid directly over the floor membrane, which must not be punctured by any fixings through the floor. When a timber floor finish is preferred you must allow an expansion gap around the wall edge.

Speak to the supplier of the floor finish to confirm the correct size of this expansion gap.

Data Sheets

Technical Data Sheet

Delta MS20 Product Brochure

Delta Cavity Drain Systems Brochure

Delta Ancillary Products Brochure

Declaration of Performance (DoP)

BBA Certificate

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