Wykamol CM8 Waterproof Membrane (8mm Stud)

Wykamol CM8 Waterproof Membrane is a High Quality, BBA Approved, 8mm Stud Basement Waterproof Tanking Membrane. Wykamol CM8 is manufactured from High Density Polyethylene and is impermeable to water and water vapour.

Wykamol CM8 Waterproof Membrane is suitable for the waterproofing of earth retained Walls, Floors and Vaulted Soffits below ground level (i.e in Basements).

  Wykamol CM8 Waterproof Membrane is supported by BBA Certification Certificate Number 18/5595.

Available in 10M²20M² and 40M² Rolls.


Sale price £115.00 Regular price
ex. VAT
Regular price £138.00 £138.00 Sale price Regular price £0.00
inc. VAT

Wykamol CM8 Waterproof Membrane is a High Quality, BBA Approved, 8mm Stud Basement Waterproof Tanking Membrane. Wykamol CM8 is manufactured from High Density Polyethylene and is impermeable to water and water vapour.

Wykamol CM8 Waterproof Membrane is suitable for the waterproofing of earth retained Walls, Floors and Vaulted Soffits below ground level (i.e in Basements).

  Wykamol CM8 Waterproof Membrane is supported by BBA Certification Certificate Number 18/5595.

Available in 10M²20M² and 40M² Rolls.

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Wykamol CM8 Waterproof Membrane

Wykamol CM8 Cavity Drain Membrane is an 8mm studded Waterproof Membrane, suitable for 'Type C' Waterproofing in Basements and delivering a Grade 3 Environment to BS8102:2009 and NHBC Chapter 5.4.

Wykamol CM8 has a life expectancy of the design life of the building / structure.

Typical Uses:

  • Walls

  • Floors

  • Vaults

  • Tunnels

  • Waterproofing Applications Below Ground Level

Benefits & Features:

  • BBA Approved

  • Creates a Dry, Habitable Living Space in Areas Previously Suffering From Damp / Wet Conditions

  • Waterproof, Salt Inhibiting, Rot and Contaminate Resistant

  • Quick to Install - Minimal Preparation Needed to Wall Surfaces

  • Easily Cut Down Using a Sharp Blade

  • No Drying Out Process - Redecoration Can Occur Immediately

  • Little or No Damage to the Existing Structure

  • Low and High Temperature Tolerance

  • Part of a 'Type C' Cavity Drain Membrane System in Line With BS8102:2009

  • Clear in Colour for Easy Application and Fixing of Wykamol CM Brick Plugs

Associated Products:

  • Wykamol CM Brick Plugs: For Fixing the Membrane to the substrate.

  • Wykamol Membrane Tape: Provides a double-sided waterproof seal when joining Membranes along the flange where they overlap.

  • Wykamol Rope: Used to form a seal around the neck of the Waterseal Plug if not using Sealing Washers

  • Wykamol Corner Strip Tape: Used to link Waterproof Membranes at Floor to Wall joints.

  • Wykamol Anti Lime Sealer: Used for the control of primary and secondary efflorescence in concrete mixes. Should be applied to concrete surfaces prior to the installation of a 'Type C' Cavity Drain Membrane System to prevent the ‘leaching’ of free lime from the concrete.

  • Waterguard Basement Channel: A PVC Drainage Channel System which should be fitted around the periphery of an internal floor at the vulnerable wall / floor junction. Any water entering the building through walls or curved soffits is controlled behind the membrane and enters the channel through before being diverted to a Mechanical (Sump and Pump System) or Natural drainage point.

  • Basement Sump & Pump Systems: Complete water control systems principally designed for use in below ground structures to control water ingress.

Technical Data:

Material High Density Polyethylene (HDPE)
Unit Weight 0.5Kg/m²
Sheet Thickness 0.45mm
Stud Height 7mm
Colour Clear (Semi-Transparent)
Water Tightness - 60 kPa; 24h (EN 1928) Pass
Working Temperature -50°C to +80°C
Softening Temperature 126°C
Tensile Strength MD (BS 12311-2) 416 N
Tensile Strength CD (BS 12311-2) 488 N
Resistance to Static Loading (BS 12730) >20 Kg
Compressive Strength (BS EN ISO 25619-2) 180 kN
Reaction to Fire (BS EN 13501-1 :2007+A1:2009) Class E
Type of Application Type V
Life Expectancy Lifetime of Structure


When used in new construction, the concrete slab must be laid in accordance with BS 8204-1:2003+A1:2009 to achieve a flat surface not deviating more than 5mm from the underside of a 3000mm straight edge.

Unsound plaster, render or screed should be removed and surfaces made level, with floors to the above tolerances. This can be achieved using Universal Mortar, or a 3:1 sand:cement mix incorporating Renderproof Waterproofing Additive.

Leave all new works to dry thoroughly before any membranes are fixed.

In case of walls suffering from mould or masonry fungi, prior to fixing the membrane, remove surface contamination by brushing, then apply a Masonry Biocide in line with the relevant Technical Data Sheet

If Dry Rot (Serpula Lacrymans) is present in the walls, this will require detailed assessment before proceeding.

Above ground level it is recommended, that where possible, all sources of moisture are alleviated at the source using a DPC such as Ultracure, before applying Wykamol CM8 Membrane. This reduces potential damage to masonry and timber etc.

We recommend an application of Wykamol Anti Lime Sealer to the concrete walls and slab, before an application of CM8, to prevent lime efflorescence and dusting, which can block perimeter drainage channels.

Application on Walls

Wykamol CM8 is fixed with the studs against the wall to create an air / depressurisation gap.

The membrane can be fixed either vertically or horizontally. When making this decision, you will need to take into account the size of the area to be lined, and the height of the walls relative to the width of the membrane. 

Horizontal fixing requires less cuts and jointing but the full roll is very heavy at first. Vertical fixing has much lighter strips to fix, but requires that each of these is taped back together again. You may find that vertical fixing is easier, but requires more Wykamol Membrane Tape for jointing.

The membrane is fixed to the wall with the Wykamol CM Brick Plug. The CM Brick Plug has a soft rubber sealing washer fitted to the plug for sealing to the wall membrane.

Place the membrane in position as level as you can judge by eye. Using a 10mm SDS Drill Bit, drill through the centre of a stud near the top and edge to a depth greater than the fixing.

The fixing is then hammered into the pre-drilled hole until the plug sits flush in the stud. The rubber washer re-seals the hole. Level the membrane using the spirit level or laser level if used, and fix another plug about 2 metres along at the top of the sheet. The membrane will now be hanging level to the wall.

If you are fixing horizontally, continue fixing every 2 metres until you have reached the end of the roll or you have covered all of the wall(s) to be treated. It is very important to regularly check the level. If the membrane is not level, you may well find that the membrane is kinked and looks unsightly, it will also dive down when fitted around corners.

If you are fixing vertically, hang each subsequent sheet by the two fixings as described above. The subsequent sheet should overlap by at least the width of the flange of the new sheet. You may find it easier to interlock the first stud of the new sheet to the last stud of the last sheet as this helps to keep the new sheet level.

The vertical joints have to be sealed with Wykamol Membrane Tape. It is easier to apply the tape to the inner surface of the flange of the next sheet. Clean the flange and the face of the last sheet with a clean rag.

When you have fixed the new sheet level with the correct overlap, pull off the backing paper from the tape and peel down whilst applying pressure to the flange.

Once all the backing paper has been removed, apply more pressure with the palm of your hand to further seal the whole of the joint. A Hot Air Gun should be used to help sealing, especially in cold or damp conditions.

Fixing Centres:

Once the wall membrane is hanging from the top fixings the rest of the fixing plugs need to be fixed.

The spacing of these fixings is dependant on the type of wall finish to be used:

  • Timber Battens - 600mm centres vertically and 400mm horizontally.

  • Barrel Vaults - Tighter centres 300mm around the vault and 600mm down the vault.

  • Fixed Metal Track (Gypliner) - 800mm centres vertically and 600mm horizontally.

  • Brick or Block Walls restrained to the retaining wall using ties should have the fixings at centres to provide the correct number of restraints at the correct centres.

  • Free standing timber and metal frames and free standing block walls do not require specific fixing centres. In these cases use sufficient fixings to ensure the membrane is neat and tidy and reasonably tight to the wall, especially around corners and reveals.

  • When fixing the system to vaulted soffits you must ensure that enough fixings are used to keep the wall membrane tight to the soffits with no sagging.

  • All fixings should be in line both horizontally and vertically.


Battens should be pre-treated and of a minimum dimension of 25mm x 38mm although you may find that 25mm x 50mm offers better fixing at the edge of the plasterboard.

The battens can be fixed into the CM Brick Plugs without piercing the membrane, by using 5mm (size 10) self-tapping screws. The plug will take 30mm of screw, so be sure to purchase the correct length for the thickness of batten.

Over-tightening of over length screws can loosen the plug. Be very careful not to puncture the wall membrane when drilling and fixing the battens. Battens should be fixed so that all plasterboard edges are supported. Use a Timber Treatment to protect cut battens.

Once the battens are fitted into position, plasterboard can be fixed to them using clout nails or preferably plasterboard screws. Care should be taken not to exceed the depth of the battens with the screws, and thereby puncture the membrane.

Alternative Fixings:

Other finishes may be employed depending on the requirements of the specifier.

Free Standing Frame:

This method should be employed if the wall is undulating, as with some stone structures or where space loss is a secondary consideration. The frame would be fixed to the soffit and the floor finish with the supplied ‘U’ channels.

With the increasing requirement of insulation to meet Part ‘L’ of building code, the use of these frames is becoming more popular, the thickness of insulation required is often in excess of the thickness of the frame, and so the use of these frames does not add extra depth to the wall build when using this method.

Because the frame is free standing and has no relationship with the wall membrane, very few fixings are required and so this wall finish above allows for the fastest and most efficient method of fixing Wykamol CM8 to the wall.

Proprietary Fixing Systems:

Fixing systems such as Gypliner or Lafarge can be used. It is also possible to use metal profile systems when constructing new internal walls.

Internal Block Walls:

If preferred the system can provide a water and vapour proof barrier, and then be lined with a block or brick inner skin. Special ties are available that fit into the CM Brick Plug for lateral restraint of the internal wall. The ties and retaining clips can also be used for the fixing and holding in place the wall insulation.

Application On Floors

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 For Floor Membranes:

Any 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 limescale so it is important for water to flow uninterrupted to the drainage point.

Wykamol Waterguard Drainage Channel:

Wykamol Waterguard Channel is placed at the wall / floor junction and collects water from behind the wall membrane and receives water at the wall/floor junction. Wykamol Waterguard Channel 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 Wykamol Flexi Jetting Eyes into the system.


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.

Wykamol Membrane 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 membrane to the up-stand of the Wykamol Waterguard Channel with Wykamol Corner Strip Tape. Use a heat-gun to dry the membrane surface and to assist with the bonding of the tapes.

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

If there are any services 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 Damp Proof Course (DPC) is laid over and sealed to the service with Wykamol Rope, and around its perimeter with Wykamol Membrane 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.

Fast Track Application of Floor Finishes:

Following the installation of new concrete slabs and screeds, it is normal to expect lengthy drying periods before floor finishes can be applied.

The membranes can be laid onto green concrete as soon as it is ‘walkable’, allowing instant application of floor coverings without reference to RH levels.

The construction moisture is controlled in the air gap.

Installation to Vaults

A ceiling which is to be covered, as in a vaulted cellar construction, should be fixed and lapped in such a way so that water does not pond behind the system.

The laps and joints should also be detailed correctly to allow correct drainage, and prevent water from sitting on joints. CM Brick Plug with a seal made from Wykamol Rope should be used for application to vaulted ceilings.

Where flat soffits are being considered it is imperative that they should have a fall in line with drainage requirements.

Again, sagging of the membrane should be avoided to prevent ponding.


Where a membrane is to be installed in vaulted cellars our experience shows that the best method of application is as follows:

Measure the depth of the vault from front to back wall and allow for a down turn at each end of 200mm. Unroll the sheet and cut to size.

Estimate the approximate centre of the arched ceiling and mark it. Measure down the arch 1.2 meters from there and again mark it. Strike a horizontal line along the wall from back to front. This will give you a guide line for your sheet edge as you fix it along the length of the ceiling, thereby keeping your sheet sections symmetrical. You may wish to hammer in masonry nails to the guide line to give a physical edge to the guide line.

Offer up your first section of membrane to the ceiling allowing a lap to the back wall of 200mm. Using your guide line to keep the sheet square, drill and fix the sheet along the apex of the arch following the same line of studs.

The CM Brick Plug with Wykamol Rope should be used to seal the plugs.

NOTE: The Rubber Sealing Washers should not be used with the CM Plugs for this application as the washers are not suitable for this purpose.

The fixings should be fixed through the centre of the membrane studs at approximately 600mm centres.

It should be remembered that the plugs provide the fixing points for your battens; therefore they should be kept in line.

Your next section of membrane is again cut to size allowing a 200mm lap at each end. Before offering up the next sheet, a Wykamol Tape joint should be applied to the edges of the first sheet, either on the flanged edge or between the last two rows of studs on the none-flanged edge.

With the protective paper left on the tape you can now offer up the next sheet ensuring that you use the flanged edge to overlap onto the sealing tape.

Once you have the second sheet positioned correctly over the sealing tape, remove the protective paper working out from the middle and effect a seal.

You can now carry on fixing the sheet as previously described. This process is repeated until you have covered the arched walls to the springer and the vertical walls below the springer, maintaining a 200mm lap to the end walls.

Vaults - End Walls:

At the end walls of the vaulted construction an ‘end piece’ of flat membrane is fitted to the end wall of the vault. The 200mm lap from the soffit membrane is cut in fans to fit the curve and sit neatly against the wall, filling each cut with a small piece of Wykamol Rope or Wykamol Membrane Tape. Do not make the cuts all the way up to the ceiling and make as few cuts as possible.

Measuring the highest point of the arch, the ‘end piece’ membrane is cut to size and fixed to the end walls in front of the fanned ceiling membrane. The membrane is then trimmed to fit neatly into the curve of the ceiling.

The end wall membrane is then pulled back at the sides and around the arch to expose the studs on the reverse side.

Using Wykamol Membrane Tape, a joint is made by the same method at the stud / stud joint details, with the exception that around the arch the rope should follow the contour of the ceiling curve.

Door Reveals:

When you fit the Wykamol Membrane to the end wall with the door opening, please bear in mind that you will have to fit a section of membrane around the door head and lapped down the sides by approximately 100mm.

You can then wrap the wall membrane around the sides, maintaining the correct drainage detail and forming an overlap.

This application detail will produce a small gap on the angle of the door opening.

This should be sealed using Wykamol Corner Strip Tape.

Alternatively, Newton 601 Slimline or Platon Stop Membranes can be used a flat DPC in lieu of the studded membrane if space is limited.

Overhead Intrusions:

Where service pipes, electrical wiring or other intrusions occur overhead or around the arch, these should be re-sited to a vertical surface where they can be better sealed and re-situated on the dry side of the system.

Most services can be concealed between the battens. Services and protrusion should be collated where possible and passed through a pipe sealed with a pipe sleeve.