Wykamol CM8 Waterproof Membrane Kit

Health & Safety And Installer Competency

Wykamol CM8 should be installed by competent operatives who understand damp proofing, structural waterproofing and Type C drained protection. The sheet is straightforward to cut and fix, but the finished system depends on correct assessment, preparation, fixing, jointing, drainage, discharge, protection and maintenance access. Wykamol CM8 must not be treated as a stand-alone barrier capable of resisting hydrostatic pressure without a functioning drainage route.

A waterproofing design specialist should be involved where required by BS 8102:2022, the complexity of the work, the intended use of the space, building-control requirements or the structural warranty provider. Habitable basements, high water-risk sites, pumped systems, combined waterproofing designs and projects with complex penetrations or level changes require particularly careful coordination.

Follow normal site precautions. Although the membrane itself is not expected to create a specific hazard during normal handling, drilling, cutting, hammering, heat-gun use and work in confined below-ground spaces introduce their own risks. Basements and cellars may have restricted lighting, ventilation, access and escape routes. Complete the appropriate risk assessments, confirm safe access and provide adequate lighting and ventilation before starting.

Wear suitable PPE for the work, which may include gloves, hard hat, eye protection, high-visibility clothing, safety footwear, hearing protection and respiratory protection when drilling dusty masonry. Follow the safety information for every chemical preparation, mortar, biocide, sealer, adhesive and ancillary product used with the membrane.

Before drilling, scan for concealed electrical cables, water pipes, gas services and other hazards. Plan all fixing lines, membrane joints, Waterguard and Floor Drain routes, sump positions, service entries and final finishes in advance. Drill through the centre of the selected membrane stud and control dust so that excessive debris does not fall into the cavity or drainage channel. Use correctly erected access equipment for high walls, vaults and soffits.

System Design Principles

Wykamol CM8 is an 8mm-class cavity drain membrane for Type C waterproofing and damp-proofing systems. Type C construction accepts that some water may pass through the retaining structure and manages it on the inside using a cavity, collection channels and a safe discharge. Where gravity drainage is not dependable, the system normally incorporates a sump chamber and one or more pumps.

The internal cavity relieves and controls water rather than attempting to hold it back at the inner face. For this reason, the design must create an uninterrupted route from every potential entry point to the drainage system. The CM8 cavity, wall-to-floor detail, Wykamol Waterguard, any Floor Drain runs, outlets, sump chamber, pump and discharge pipework must work as one coordinated arrangement.

Base the waterproofing design on BS 8102:2022, the water-risk assessment, ground conditions, structure, anticipated water pressure, intended use and required internal environment. A Grade 3 environment may be required for habitable below-ground rooms, but Grade 3 performance is a result of the complete system. It depends on appropriate design, workmanship, drainage capacity, pump provision, ventilation, maintenance and protection from later damage.

If drainage channels become blocked, water entry exceeds the design capacity, the gravity outlet backs up, a pump fails or mains power is lost, the waterproofed space may be at risk. Inspection ports, accessible sump covers, high-water alarms, pump redundancy and battery back-up should therefore be considered at design stage rather than added after the installation is concealed.

For below-ground and earth-retaining structures, the designer must also determine whether combined waterproofing protection is necessary. Depending on the risk and warranty requirements, this may combine Type C with a compatible Type A barrier or Type B water-resistant structure. Wykamol CM8 can form the internal drained protection element, but the complete specification must be selected and approved for the particular project.

Suitable Substrates

Wykamol CM8 can be installed on suitable walls, floors, vaults, tunnels and other structures above or below ground level. Typical backgrounds include concrete, brickwork, blockwork, stone, masonry, sound render and sound screed, provided the construction is stable, capable of accepting the specified fixings and suitable for the intended drainage and finishing build-up.

For new floor construction, concrete bases should be laid in accordance with BS 8204-1:2003+A1:2009. The CM8 technical information calls for a flat surface with no more than 5mm deviation beneath a 3000mm straightedge. Controlled falls, local drainage details and the structural design must also be coordinated with the waterproofing layout.

Assess existing walls and floors before installation. Remove or repair unsound plaster, weak render, defective screed, friable masonry, sharp projections, severe depressions and unstable areas. CM8 generally needs less preparation than a fully bonded tanking product, but the background must still hold the fixings, allow the sheet to lie without damaging stress points and permit water to reach the drainage system without obstruction.

Do not install over unassessed structural movement, active collapse, contaminated surfaces requiring specialist remediation or hazardous materials. Structural cracks, failed joints and active water flows may require engineered repair or water-stopping measures before the Type C system is completed.

Preparation Of Walls, Floors And Soffits

Remove unsound plaster, render and screed, then level or re-profile the substrate where required. Wykamol Universal Mortar or a suitable 3:1 sand-and-cement repair mix incorporating Renderproof Waterproofing Additive may be used for appropriate repairs. Follow the separate product instructions and allow new cementitious work to dry thoroughly before installing the membrane or applying butyl tapes.

Brush away visible mould and masonry fungal contamination, then treat the prepared surface with Wykamol Microtech Masonry Biocide in accordance with its current technical and safety information. If dry rot is present, stop and arrange a detailed assessment of the moisture source, affected timber and adjoining construction. A membrane must not be used to conceal unresolved timber decay.

Above ground level, repair avoidable sources of moisture wherever practical. Check rainwater goods, external ground levels, pointing, render, plumbing, roofs, flashings and other defects. Where rising damp control is appropriate, Ultracure Damp Proofing Cream may be installed to the correct specification before CM8. This reduces unnecessary moisture loading and helps protect surrounding masonry and timber.

Treat concrete walls and slabs with Wykamol Anti-Lime Sealer where new concrete, free lime, efflorescence or dusting could affect the cavity drain system. Lime carried by water can harden within drainage routes and increase maintenance or blockage risk. Prepare, dilute, apply and cure Anti-Lime Sealer strictly in accordance with its own instructions; do not apply it to pooled water or unsuitable surfaces.

Clean the final background and remove loose debris before closing the cavity. Pay particular attention to the wall-to-floor junction, channel troughs, sumps and access details. Construction debris left behind the membrane can restrict drainage, contaminate the channel or make later flushing more difficult.

Anti-lime sealer being applied to prepared concrete before installation of Wykamol CM8 Waterproof Membrane.

Tools And Ancillary Products Required

Typical installation tools include an SDS Plus hammer drill, the included 10mm x 160mm masonry bit, spare or alternative-length 10mm bits where required, a rubber mallet or club hammer, sharp utility knife with spare blades, tape measure, long level, straightedge, marker, clean rags, soft roller or firm hand-pressure tool for tapes, and a suitable vacuum or dust-control arrangement. A laser level is useful for long runs, plug lines, channel setting-out and floor levels. Provide suitable task lighting and access equipment for basements, high walls and vaults.

A controlled hot-air gun may be useful for removing light surface moisture and improving butyl-tape adhesion in cold conditions, but it must not overheat, melt or distort the HDPE membrane. Open flames must never be used. All surfaces receiving tape or rope must be clean, dry and free from dust, grease, condensation and loose material.

The kit supplies the stated quantity of Wykamol CM Brick Plugs & Seals and Wykamol Membrane Sealing Tape. The complete system may also require extra plugs or tape, Wykamol Sealing Rope, Wykamol Corner Strip Tape, Wykamol Fibre Tape, suitable patches or pipe collars, Waterguard and Floor Drain channels, swept corners, T-Pieces, outlets, Flexible or Extended Jetting Eyes, and a correctly selected gravity outlet or sump-and-pump arrangement. Where pumping is essential, also provide the specified discharge components, high-water alarm and any required secondary pump, back-up power or telemetry.

Do not assume that selecting a kit means every project component is present. Do not begin fixing the membrane until the kit contents have been checked, all additional critical products are available and the installation sequence has been agreed. Leaving unfinished joints, missing drainage connections or inaccessible temporary details increases the chance of contamination and damage before the system is closed.

Drainage Requirements

Wykamol CM8 must form part of a drainage-based waterproofing system. The cavity behind the membrane requires a clear and maintainable route to a safe discharge; without it, water can accumulate and the system cannot perform as intended. Wykamol Waterguard Perimeter Drainage Channel is installed at the vulnerable wall-to-floor junction to collect water from behind the wall membrane. Wykamol Floor Drain can be used where the design needs perimeter or cross-floor drainage below the finished floor build-up.

Set out the complete channel route, levels, wall-membrane termination, floor-membrane link, sump entry and outlet before breaking out or fixing begins. Use Wykamol Swept Corners at 90° direction changes and Wykamol T-Pieces where Waterguard and Floor Drain routes meet. Do not improvise sharp mitres, open junctions or pipe connections that could restrict flow or make future cleaning difficult.

Choose the outlet to suit the designed flow, pipe size, available levels and sump position. The Wykamol Universal Channel Outlet is intended for a suitable 100mm connection and incorporates jetting access, while the Wykamol 50mm Outlet can connect the channel to a sump or, where levels permit, through a wall to an appropriate gravity gully. Confirm compatibility before installation.

Maintenance access is essential. Provide Wykamol Waterguard Flexible Jetting Eyes at appropriate inspection locations and Wykamol Extended Jetting Eyes along longer runs. Wykamol information recommends Extended Jetting Eyes at approximately 10m to 12m intervals where suitable. Position every access point so it remains reachable after screed, flooring, dry lining and skirting are complete.

Where gravity drainage is unavailable, connect the channel system to a correctly sized sump-and-pump system. Select the pumps for expected inflow, vertical head, pipe resistance and discharge distance. Consider pump redundancy, non-return valves, high-water alarms, power failure, battery back-up and the consequences of downtime. Route discharged water to an approved point where it cannot return towards the structure.

Before covering the system, flush or water-test the channels and confirm free flow to the outlet or sump. Check connectors, corners, access ports and sump entries for debris or displacement. Test pumps, floats, alarms and any back-up or telemetry equipment in accordance with their instructions.

Wykamol Waterguard Channel Preparation And Installation

Coordinate the Waterguard and Floor Drain layout with the waterproofing drawings before cutting the slab, forming chases or installing CM8. Establish the channel position at the wall-to-floor junction, all changes of direction, cross-floor routes, sump connections, gravity outlets and cleaning points. The trough size and formation must suit the current Wykamol channel profile, structural slab, reinforcement, services, floor levels and approved project detail; do not assume a generic excavation is suitable for every building.

Prepare a stable, clean and correctly levelled channel bed. Remove loose masonry, laitance, drilling dust, hardened mortar and sharp debris that could displace the conduit or restrict its water-entry slots. Waterguard must follow the designed route without local high spots or reverse falls that trap water. Keep the channel aligned with the membrane cavity so water reaching the wall base can enter the conduit without passing into the internal floor build-up.

Dry-fit straight lengths, Swept Corners, T-Pieces, Floor Drain connections, outlets and jetting points before permanent floor work proceeds. Push-fit or join each Wykamol component in accordance with its current instructions, checking that the sections remain aligned and that junctions do not obstruct the internal waterway. Use purpose-made components rather than cutting sharp corners or loosely butting channel ends together.

Connect Floor Drain where the design requires cross-floor collection or a route to a central sump. Connect the specified Universal Channel Outlet or 50mm Outlet to the sump, gully or other approved discharge arrangement, maintaining the required pipe level and capacity. Keep sump entries and gravity connections secure and free from construction debris. Where pumping is required, install and test the chamber, pumps, valves, alarms and discharge before the system is concealed.

Install Flexible Jetting Eyes at suitable access positions and Extended Jetting Eyes along longer runs, including the intervals required by the project and current Wykamol guidance. Raise or form each access point to suit the finished floor and wall detail without leaving it buried behind permanent finishes. Record the positions for the building owner and future service contractor.

Before screed, insulation, flooring or dry lining closes the system, flush or water-test every channel run and observe free flow at the sump or gravity outlet. Check corners, T-Pieces, channel joints, outlets and access points for leakage, displacement, debris or backfall. Rectify every defect and repeat the test. Protect the open channel from further dust and rubble until the floor build-up is completed.

Waterguard Drainage Channel being installed at the wall-floor junction with Wykamol CM8 Membrane, helping manage water ingress within a Type C basement waterproofing system.

Wall Installation

Install Wykamol CM8 with the studs facing the wall. The studded profile must sit against the substrate so that it creates the drainage cavity behind the smooth room-facing surface. Plan the sheet orientation, flange positions, joint direction, fixing lines, wall-to-floor termination and final lining before cutting or drilling.

Offer the first sheet to the wall and align it accurately. CM8 may be installed vertically or horizontally where the system design and site handling permit, but all overlaps must shed water towards the cavity and must not leave an unsealed edge capable of directing water into the internal finish. Keep the sheet tight to corners and prevent unnecessary bridging, tension or creasing.

Drill through the centre of a membrane stud into sound substrate using the 10mm bit required for the Wykamol CM Brick Plug & Seal. Make the hole deep and clean enough for the plug to seat fully. Control drilling dust so it does not accumulate behind the membrane or enter Waterguard.

Insert the plug and drive it home with a rubber mallet or club hammer until the soft sealing washer is evenly compressed against the membrane. The washer must sit flat and must not be split, folded or displaced. Where a separate butyl fixing seal is specified because the washer is omitted or cannot seat correctly, form a complete compressed seal around the plug neck with Wykamol Sealing Rope.

For standard wall areas, space plug fixings no more than 600mm apart unless the project design, substrate, board dimensions or finishing system requires closer centres. Increase restraint where necessary at sheet edges, corners, openings and irregular areas. Align fixing rows with planned battens or support components so later trades can use the plug heads instead of creating new penetrations.

Wykamol CM8 Membrane installed on basement walls, with sealed joints and brick plug fixings creating a controlled cavity to manage moisture and direct water towards the drainage system.

Wall Fixing Centres And Internal Finishes

Choose fixing centres to suit the selected internal finish. For a battened or stud-framed lining, install Wykamol CM Brick Plugs in vertical rows roughly corresponding with the support positions. Timber battens should be at least 25mm x 38mm where following the source installation arrangement. Fix suitable battens or brackets into the plug cores with 5mm No.10 screws of a controlled length that cannot pass through the plug and puncture the membrane.

If substrate condition prevents plug heads from following a straight support line, compatible dry-lining brackets may be used to align the battens. The bracket and screw arrangement must use the existing sealed plug positions and must not introduce uncontrolled membrane penetrations.

On reasonably flat walls, the serrated heads of Wykamol CM Brick Plugs & Seals may provide fixing points for a compatible dot-and-dab board system where the project specification permits it. Apply the board adhesive to the plug heads rather than directly to the unsupported membrane. If following the source dry-lining arrangement, conventional bonding plaster is applied in dabs at least 8mm thick and covering at least 50% of the membrane area. Confirm adhesive, board, fire and moisture compatibility for the particular project before use.

Wykamol CM8 is a non-meshed membrane and is not intended to receive direct plaster or render. Where a direct wet-plaster or render finish is required, specify a suitable meshed cavity drain membrane instead. CM8 should be protected by a compatible dry-lining system, independent frame, battened board finish, permitted dot-and-dab lining, blockwork lining or other designed finish that does not puncture or overload the waterproofing layer.

Jointing And Sealing

Use the flange along the edge of the CM8 sheet to form the principal overlap wherever possible. The flange is the flat band without studs. Place Wykamol Membrane Sealing Tape inside the overlap, align the adjoining sheet and compress the complete joint firmly so that the butyl tape makes uninterrupted contact with both membrane surfaces.

On vertical wall runs, arrange the flanges vertically and place each new sheet in front of the preceding sheet so water is directed into the drainage cavity rather than towards an open edge. At a horizontal joint, position the lower sheet in front of the upper sheet. Plan the sequence before fixing because reversing a lap can create a ledge that traps debris or directs water towards the room-facing side.

Both surfaces must be clean, dry and free from dust, grease and condensation before applying tape or rope. Wipe the membrane with clean rags and allow it to dry. In a cold or damp environment, a hot-air gun may be used cautiously to remove surface moisture and gently warm the jointing area, but the HDPE must not be overheated, softened or distorted. Open flames must not be used.

For a non-flanged or irregular stud-to-stud joint, form the specified seal with Wykamol Sealing Rope, shaped and compressed into the profile so no route remains through the joint. Wykamol Membrane Sealing Tape may also be used in compatible stud-interlock details where it can be fully compressed between clean mating surfaces.

Where severe water ingress is present or reasonably foreseeable, add a wider face seal with Wykamol Corner Strip Tape if required by the design. Wykamol Corner Strip Tape is also useful at wall-to-floor transitions, patches, protrusions and awkward junctions. It does not remove the need for a correctly formed primary overlap beneath it.

Seal mitres, shaped cuts, columns, vault sections, pipe details and three-dimensional junctions with the appropriate combination of Wykamol Membrane Sealing Tape, Wykamol Sealing Rope, Wykamol Corner Strip Tape, membrane patches and compatible collars or sleeves. Wykamol Fibre Tape may provide additional finishing or reinforcement support where specified, but it must not be relied upon as the sole waterproof seal.

Roll or press every joint along its full length. Inspect for fish-mouths, bridged sections, trapped dust, stretched membrane and insufficient compression before the next sheet or finish hides the detail.

Wall-To-Floor Junction And Waterguard Integration

The wall-to-floor junction is commonly one of the highest-risk points in a basement and must be detailed as part of the drainage design. Terminate the wall membrane so water from the cavity can enter Wykamol Waterguard Perimeter Drainage Channel without passing into the internal floor build-up. Keep the channel inlet zone and water-entry slots clear; do not seal the membrane in a way that blocks the intended drainage path.

Form the perimeter trough or channel bed to the dimensions and levels shown on the approved waterproofing detail and current Wykamol instructions. Position Waterguard at the wall base so it remains stable, aligned and connected to the CM8 cavity. The exact trough size, support material, channel level and membrane termination must suit the structural floor and project design rather than a generic site assumption.

Use purpose-made Wykamol Swept Corners, T-Pieces, Floor Drain sections and outlets rather than improvised cuts. Provide Flexible Jetting Eyes at suitable inspection positions and Extended Jetting Eyes along longer runs, including the intervals required by the design. Complete, flush and test the drainage route before laying floor membrane, insulation, screed or other permanent finishes.

Where a floor membrane is included, link it continuously to the wall membrane and drainage detail using the specified overlap, Wykamol Membrane Sealing Tape and Wykamol Corner Strip Tape. The junction must preserve waterproofing continuity while allowing water from the wall cavity to enter Waterguard; do not create a sealed pocket above or behind the channel.

Floor Installation

Before laying Wykamol CM8 on a floor, ensure the slab or screed is clean, stable, reasonably dry at the surface and free from oil, loose material, sharp projections and debris. Repair holes, ridges and severe depressions. New concrete bases should meet the specified flatness requirement of no more than 5mm deviation beneath a 3000mm straightedge, and any designed falls must lead water towards the drainage arrangement rather than create isolated low points.

Apply Wykamol Anti-Lime Sealer to suitable concrete where required to control free-lime leaching and dust. Allow all levelling, repair and anti-lime treatments to reach the condition stated in their individual instructions before closing the floor cavity.

Roll out the membrane with the studs facing down towards the floor so the studded profile creates a drainage space beneath the smooth upper face. Cut with a sharp blade and fit neatly around walls, columns, sumps, drainage channels and unavoidable service details. Avoid excessive small pieces and unnecessary seams.

Lay the next sheet so its flange overlaps the preceding sheet. Apply Wykamol Membrane Sealing Tape to clean, dry surfaces inside the overlap and compress the joint firmly along its full length. Where no flange is available, use the designed combination of Wykamol Sealing Rope, Joint Sealing Tape, Wykamol Corner Strip Tape and a membrane patch to create a continuous seal.

Connect the floor membrane to Waterguard, the wall membrane, DPC details, sump entries and other terminations in accordance with the system design. Use Wykamol Corner Strip Tape where a broad face-applied seal is required. Check that the completed edge detail does not obstruct water entering the channel from the wall or floor cavity.

If the final floor build-up is too deep for Waterguard to collect condensation from the room-facing side of the wall membrane, a Newton Condensation Strip may be included as a separate edge route. This deals with surface condensation only; it does not replace cavity drainage behind the membrane.

For a floating floor, CM8 may be overlaid with compatible closed-cell insulation before tongue-and-groove flooring is installed. Maintain a 10mm expansion gap around the perimeter unless the flooring or system design requires otherwise. Alternatively, a conventional sand-and-cement screed approximately 65mm thick may be laid over the membrane where structurally and technically suitable.

Where a high-load insulating drainage layer is needed, specify Wykamol High Load Closed Cell Insulation or Newton CDM Fibran XPS 500-C as part of a compatible build-up. These 50mm-class thermal spacers use a grooved face to preserve drainage and shiplap edges to reduce the risk of screed entering open joints. Follow the board orientation, loading, edge, joint and floor-finish requirements for the chosen product.

Protect the membrane throughout floor work. Use load-spreading boards where necessary, keep reinforcement, tools and sharp offcuts away from the sheet, and prevent screed or adhesive entering drainage cavities or access ports. During relevant wet finishing work, keep atmospheric relative humidity below the limit stated in the technical instructions; the source membrane information specifies below 70% RH during application. Do not install impermeable floor coverings until the screed is dry enough, with the source information requiring screed moisture below 75% RH.

Vaulted Soffit Installation

Wykamol CM8 can line vaulted ceilings, arches and sloping underground structures when the membrane can be fixed tightly to the substrate and water can drain continuously to the designed collection point. Survey and set out the vault before cutting. Plan sheet sizes, joint direction, end-wall transitions, fixing density and access so the membrane follows the curve without bridging, excessive tension, deep creasing or sagging.

Measure and cut each section accurately, then hold the studs against the vault while drilling through the centre of selected studs into sound substrate. Use enough fixings to keep the sheet firmly supported over the complete curved surface. Standard Wykamol CM Brick Plug washers may be used where they sit flat and compress evenly. On details where the washer is deliberately omitted or cannot seat reliably, form a complete seal around the plug neck with Wykamol Sealing Rope in accordance with the specified detail.

Keep cuts to the minimum required. Seal flanged laps with Wykamol Membrane Sealing Tape and use Wykamol Sealing Rope, Wykamol Corner Strip Tape, patches and compatible reinforcement at mitres, curved joints, returns and end-wall junctions. Every cut edge and penetration must be inspected before the lining is concealed.

The drainage cavity must remain continuous from the crown and sides of the vault to Waterguard or another designed collection route. Do not permit the sheet to sag between fixings because low pockets can retain water, sediment and biological debris. Vault work should be undertaken from suitable access equipment by installers able to see and compress every overhead joint safely.

Typical vaulted soffit installation showing Wykamol CM8 Waterproof Membrane fixed to a curved vault, with sealed joints, drainage detail and Wykamol WaterGuard channel integration.

Flat Soffit Restrictions

Do not line a flat below-ground soffit with Wykamol CM8 unless it has a reliable minimum slope of 10% towards the designed drainage route. A flat or inadequately sloping overhead surface can allow water to pond behind the membrane, load the fixings, contaminate the cavity and place stress on joints and terminations.

If the soffit does not provide the necessary fall, specify another waterproofing approach. CM8 is better suited to vaulted, arched or sloping overhead construction where gravity can move water to the collection point. Even on a compliant slope, the membrane must remain tight to the substrate and must not sag.

Door Reveals, Corners And Junction Details

Form internal and external corners so the CM8 sheet sits tightly into the angle and provides a well-defined edge for the subsequent lining. Do not bridge across a corner and leave a rounded, unsupported void. Use correctly located Wykamol CM Brick Plugs to hold the membrane into the angle without overstressing or tearing a stud.

Where the sheet can be folded cleanly, retain the continuous sheet and secure it. Where cutting is necessary, keep the cut controlled and seal the resulting joint with Wykamol Membrane Sealing Tape, Wykamol Sealing Rope, Wykamol Corner Strip Tape or a purpose-cut patch as required by the geometry. Avoid building several bulky tape layers into a corner unless the detail has space to compress them correctly.

Treat door and window reveals, columns, returns, steps and openings as complete waterproofing details rather than simple trimming points. Lap, wrap or patch the membrane so the drainage cavity remains continuous and all exposed edges are sealed. Coordinate the final lining, frame fixings and threshold before closing the detail; later drilling through a finished reveal is a common route for accidental damage.

Where a sheet DPC passes through an internal wall or reveal, connect it to CM8 with Wykamol Membrane Sealing Tape and add Wykamol Corner Strip Tape where a wider face seal is required. Maintain continuity with any above-ground damp-proofing arrangement without blocking the Type C drainage route below ground.

Protrusions Through Wykamol CM8

Avoid passing pipes, cables, ducts and conduits through Wykamol CM8 wherever practical. Each penetration is a potential weakness and must be included on the waterproofing drawings. Re-route services on the room side of the lining or through a planned service zone where possible.

If a penetration is unavoidable, cut the smallest neat opening that permits the service to pass without tearing the membrane. Pack and compress Wykamol Sealing Rope around the service to form a continuous butyl seal. Cover the detail with Wykamol Corner Strip Tape or a membrane patch where a broader seal is needed. A compatible pipe collar or sleeve should be fully sealed to both the membrane and the service material.

Allow for pipe movement, vibration, thermal expansion and future maintenance. A rigid tape patch applied over a moving or contaminated pipe may fail even when it initially appears sealed. Clean and prepare plastics, metals and coated services in accordance with the sealing accessory instructions, and use a proprietary collar where simple rope-and-tape detailing cannot accommodate movement.

Floor penetrations require particular care because water can bypass the membrane and enter the finished floor build-up. Use Wykamol Sealing Rope, Wykamol Membrane Sealing Tape and a purpose-cut CM8 or DPC patch as required. Seal the full patch perimeter, inspect it from every side and, where practical, test it before installing insulation, screed or flooring.

Protection Of Wykamol CM8 After Installation

Protect CM8 immediately after installation. On walls, protection may be provided by an independent lining, framed dry lining, correctly fixed battens and boards, an approved dot-and-dab system, blockwork or another specified finish. On floors, use compatible closed-cell insulation with tongue-and-groove flooring, an adequately designed screed or another load-spreading build-up that will not puncture the sheet.

Tell every follow-on trade that the waterproof membrane must not be drilled, nailed or screwed through. Use the existing Wykamol CM Brick Plug cores for approved secondary fixings and select screw lengths that cannot reach beyond the plug. Mark no-fix zones at channels, sumps, pipework and complex details before covering the membrane.

Keep sharp tools, board corners, reinforcement, rubble, heavy point loads and uncontrolled site traffic away from unprotected CM8. Do not drag materials across floor membrane. If temporary protection is removed, reinspect the exposed area before installing the permanent finish.

Protect stored and installed membrane from prolonged direct sunlight, high temperatures and open flame. CM8 is intended to remain protected within the building build-up rather than exposed as a finished surface.

Ventilation And Humidity Control

Wykamol CM8 manages water and moisture entering through the structure; it does not remove water vapour generated inside the finished room. Cooking, showering, drying clothes, occupation and inadequate heating can still produce condensation on cold surfaces even when the Type C system is functioning correctly.

Provide an appropriate ventilation, heating and humidity-control strategy for the intended use. Mechanical extract or whole-room ventilation is especially important in bathrooms, kitchens, utility rooms and other high-moisture areas below ground. The ventilation design must comply with the wider building specification and should remain maintainable after occupation.

Do not diagnose condensation as membrane failure without checking humidity, surface temperatures and ventilation, but equally do not assume visible water is condensation until drainage, pumps, joints and penetrations have been inspected. The two sources require different remedial actions.

Where condensation can run down the room-facing surface of the wall membrane and the floor build-up prevents it reaching Waterguard, consider Newton Condensation Strip as part of the designed edge detail. Keep its route clear and do not bridge it with sealant, plaster, screed or skirting adhesive.

Inspection Before Finishes

Inspect the complete CM8 installation before it is covered. Check the membrane for punctures, cuts, tears, crushed studs, sagging, loose plugs, distorted washers, poorly compressed joints, bridged corners and unsealed penetrations. Confirm that each repair is complete before boards, battens, insulation, screed or flooring make the area inaccessible.

Check every Wykamol Membrane Sealing Tape overlap for continuous contact. Confirm that Wykamol Sealing Rope remains correctly positioned and compressed, and that Wykamol Corner Strip Tape is fully bonded beyond the edge of each repair or junction. Pay particular attention to the base of walls, door openings, columns, external corners, pipe clusters and vault end details.

Inspect the water-management system separately. Confirm Waterguard and Floor Drain positions and levels, Swept Corners, T-Pieces, Universal or 50mm Outlets, sump entries, Flexible Jetting Eyes and Extended Jetting Eyes. Remove debris and verify that each cleaning point and sump cover remains reachable after the proposed finish is installed.

Flush or water-test the drainage route in accordance with the design. Test all pumps, floats, non-return valves, alarms, battery back-up and telemetry. Confirm the discharge point accepts the flow and does not return water towards the building. Record the inspection and retain photographs of critical details before concealment.

Flexible jetting eye detail within a Wykamol CM8 membrane installation, providing accessible maintenance for the Wykamol WaterGuard drainage channel.

Repairs To Wykamol CM8

If a fixing hole is drilled through the wrong stud, clean and dry the area, fill the penetration with Wykamol Sealing Rope and over-seal it with Wykamol Corner Strip Tape. Extend the face tape well beyond the damaged point and press it firmly to the prepared membrane. Install the replacement Wykamol CM Brick Plug through a different stud into sound substrate.

For a small cut or puncture, flatten the damaged area without enlarging it, then bridge it with Wykamol Corner Strip Tape on clean, dry membrane. The tape must extend beyond the defect on every side and remain fully supported. Remove loose fragments that would prevent adhesion, but do not pull a tear wider.

For a larger hole, cut a CM8 patch with a generous sound margin around the damage. Where the studs interlock neatly, seal the patch perimeter with Wykamol Membrane Sealing Tape inside the overlap. Where the profile cannot form a reliable interlock, use Wykamol Corner Strip Tape around the complete face perimeter, adding Wykamol Sealing Rope beneath irregular sections where required.

Take extra care with floor and vault repairs because these areas may see greater water movement or mechanical loading. A repair that cannot be fully accessed, supported, compressed and inspected should be removed and replaced with a larger membrane section rather than concealed as a doubtful patch.

Maintenance And Future Alterations

Wykamol CM8 itself requires little routine attention after it is protected, but the drainage and pumping system must remain accessible and serviceable. Maintain Waterguard, Floor Drain, outlets, jetting points, sump chambers, pumps, valves, alarms and discharge pipework in accordance with the waterproofing design and each component manufacturer's instructions.

Set the maintenance schedule from the water risk, lime and sediment exposure, pump duty, occupancy, warranty requirements and the instructions for the installed system. High-risk or heavily used arrangements may require more frequent inspection and servicing than low-risk gravity-drained applications. Do not wait for visible dampness or a high-water alarm before checking a system on which a habitable basement depends.

Use Waterguard Flexible Jetting Eyes and Extended Jetting Eyes to inspect and flush the channel system. Keep their covers visible or clearly documented and removable. Clean silt and debris from the sump, operate each pump, test floats and non-return valves, check the discharge and confirm every alarm and back-up device works. Wykamol information recommends Extended Jetting Eyes at approximately 10m to 12m intervals where suitable.

Where the waterproofed space relies on pumping, arrange competent servicing and maintain an emergency response plan. Consider a secondary pump, high-water alarm, battery back-up and telemetry where the consequence of failure justifies them. Replace batteries and worn pump components at the intervals specified for the installed equipment.

Control future alterations. Shelving, kitchens, sanitary fittings, skirting, cupboards, floor fixings, new services and later refurbishment must not penetrate CM8 or obstruct Waterguard without a reviewed waterproofing detail. Provide the owner with drawings, photographs, operating instructions, maintenance schedules and the location of no-fix zones and access points.

Key Limitations

• Wykamol CM8 is one component of a Type C cavity drain system. It must not be relied on as a stand-alone barrier against hydrostatic pressure.
  
  

• Water behind or below the membrane must have a continuous route to Waterguard, a suitable gravity outlet or a correctly selected sump-and-pump arrangement.
  
  

• The membrane alone does not guarantee a Grade 3 environment. The complete structure, waterproofing design, drainage, pumps, details, finishes, ventilation and maintenance determine the internal result.
  
  

• Kit size describes the nominal gross area of the membrane roll, not guaranteed installed coverage. Allow for overlaps, trimming, corners, junctions, penetrations, repairs and reasonable waste.
  
  

• The included plug, tape and drill-bit quantities are the stated kit contents, not a substitute for a project take-off. Order supplementary components wherever fixing centres, joint lengths, substrate hardness or detailing demand exceeds those quantities.
  
  

• Do not use CM8 on a flat below-ground soffit unless the soffit provides a minimum 10% slope to drainage. Prevent sagging on all overhead applications.
  
  

• CM8 is non-meshed and must not receive direct plaster or render. Use a compatible dry lining or specify a suitable meshed membrane for a direct wet finish.
  
  

• Seal below-ground fixing points with the supplied Wykamol CM Brick Plug washers or with a correctly compressed Wykamol Sealing Rope detail where the washer is omitted by design.
  
  

• Keep tapes and rope clean and dry during installation. Butyl seals will not perform reliably over dust, grease, standing water, condensation or loose material.
  
  

• Do not allow later screws, nails, brackets, services or floor fixings to puncture the membrane. Repair all accidental damage before concealment.
  
  

• Protect the membrane from prolonged UV exposure, sharp objects, high temperatures and open flames.
  
  

• Cavity drain performance depends on inspection and maintenance. Do not conceal Waterguard jetting points, sump covers, alarms or serviceable components.
  
  

• Seek specialist design advice for habitable basements, high water-risk sites, complex structures, combined waterproofing, pumped systems, structural movement or warranty-controlled work.

Storage And Shelf Life

Store Wykamol CM8 rolls upright, under cover, on a stable surface and away from prolonged sunlight, high temperatures, ignition sources and open flames. Protect the roll edges and flanges from crushing, contamination and distortion. Do not stack or handle rolls in a way that damages the stud profile.

The stated life expectancy is equivalent to the lifetime of the structure when the membrane is stored and installed in accordance with the technical recommendations. This is an in-service durability statement, not permission to leave rolls exposed indefinitely before installation. Inspect stored material before use and reject sections with heat damage, brittleness, severe distortion, contamination or compromised edges.

Keep Wykamol Membrane Sealing Tape in its original packaging in clean, dry conditions and protect the butyl faces from dust, moisture, heat and deformation. Keep Wykamol CM Brick Plug washers clean, flat and undamaged. Store drill bits dry and inspect the cutting head and SDS shank before use. The kit has no single combined shelf-life statement; follow the current storage and service information for each supplied component.

Other Technical Information

Wykamol CM8 is manufactured from clear HDPE. The published technical information lists a unit weight of 0.5kg/m², sheet thickness of 0.45mm and stud height of 7mm. The product is described commercially as an 8mm-class or nominal 8mm studded membrane. It passes water-tightness testing at 60kPa for 24 hours to EN 1928.

Published tensile strength is 416N in the machine direction and 488N in the cross direction to BS 12311-2. Resistance to static loading is greater than 20kg to BS 12730. Compressive strength is listed as 180kN/m² in the main technical data to BS EN ISO 25619-2, while the essential-characteristics table reproduces the source declaration format of 180kN.

The listed working temperature range is -50°C to +80°C and the softening temperature is 126°C. Reaction to fire is Class E to BS EN 13501-1, application type is Type V, and life expectancy is stated as the lifetime of the structure when stored and installed in line with the recommendations.

Wykamol CM8 can contribute to a Type C system designed under BS 8102:2022, but every project must be assessed as a complete waterproofing arrangement. Product data does not replace a site-specific design, and references to a standard do not constitute third-party product certification.

The 10m² kit contains a 2m x 5m membrane roll, 30 Wykamol CM Brick Plugs & Seals, one 28mm x 22.5m roll of Wykamol Membrane Sealing Tape and one 10mm x 160mm SDS Plus bit. The 20m² kit contains a 2m x 10m roll, 50 plugs, one 28mm x 22.5m tape roll and one bit. The 40m² kit contains a 2m x 20m roll, 100 plugs, one 28mm x 22.5m tape roll and two bits. These are supply quantities; actual installed coverage and ancillary consumption depend on the project layout and specification.

Q) What is the Wykamol CM8 Waterproof Membrane Kit?

A) The Wykamol CM8 Waterproof Membrane Kit is a packaged group of core products for installing an internal cavity-drain waterproofing membrane. Its main component is a clear, studded HDPE sheet that separates new finishes from damp, wet or salt-contaminated walls and floors. The studs create a controlled drainage space through which incoming moisture can travel towards a suitable collection and discharge point. The kit also includes sealed masonry fixings, double-sided jointing tape and the correctly sized masonry drill bit. It is principally intended for Type C waterproofing in basements, cellars and other earth-retaining structures, but it must be connected to a properly designed drainage system to provide dependable protection.

Q) What is included in each Wykamol CM8 Waterproof Membrane Kit?

A) Each kit contains one roll of Wykamol CM8 membrane, Wykamol CM Brick Plugs with rubber seals, one roll of Wykamol Membrane Sealing Tape and either one or two 10mm x 160mm SDS Plus masonry drill bits. The 10m² kit provides a 2m x 5m membrane roll, 30 plugs, 22.5m of 28mm-wide tape and one bit. The 20m² kit provides a 2m x 10m roll, 50 plugs, the same tape quantity and one bit. The 40m² version provides a 2m x 20m roll, 100 plugs, one 22.5m tape roll and two bits. Drainage channels, pumps and specialist detailing products are purchased separately.

Q) How does the Wykamol CM8 Waterproof Membrane Kit work?

A) Wykamol CM8 has a nominal 8mm-studded profile that holds the membrane away from the underlying wall or floor. This forms a defined cavity in which water entering through the structure can move without contacting the new internal finish. The water is then collected by Wykamol Waterguard, Floor Drain or another compatible drainage arrangement and discharged through a safe gravity outlet or sump-and-pump system. The membrane therefore manages water rather than attempting to stop every drop at the substrate surface. Its performance depends on continuous drainage, properly sealed laps, watertight fixings, correctly treated penetrations and accessible outlets. Fitting CM8 over a wet wall without arranging discharge would not constitute a complete or reliable waterproofing solution.

Q) Is the Wykamol CM8 kit a complete basement waterproofing system?

A) The Wykamol CM8 kit supplies the principal membrane, fixing, jointing and drilling components, but it is not automatically a complete basement waterproofing system. A functioning Type C design also needs a continuous route for collecting and safely discharging water. Depending on the site, this may include Waterguard perimeter channel, Floor Drain, swept corners, T-pieces, jetting eyes, outlets, a sump, pumps, alarms and backup power. Corners, penetrations, repairs and non-flanged joints may require Sealing Rope, Corner Strip Tape, patches or collars. Preparation materials, insulation, screed, dry lining and decorative finishes are also separate. Every component should be selected from the water-risk assessment, structure, intended room use and required internal grade.

Q) Which Wykamol CM8 Waterproof Membrane Kit size should I choose?

A) Wykamol CM8 kits are available with nominal membrane areas of 10m², 20m² and 40m². Measure every wall, floor, reveal, return, column, vault and step that will receive membrane rather than relying only on the room’s floor area. The stated size is the gross roll area before overlaps, trimming, corners, service penetrations and cutting waste are deducted. Plan the sheet direction and joint positions, then calculate the number of plugs and total tape length separately. The kit’s supplied quantities may not cover a complex fixing pattern or numerous joints. If the calculated requirement is close to a kit boundary, choosing the larger option is generally safer than reducing specified overlaps or fixing centres to conserve materials.

Q) What type of waterproofing does Wykamol CM8 provide?

A) Wykamol CM8 is used within Type C drained-protection waterproofing. This approach accepts that water may pass through an earth-retaining structure and controls it on the inside using a cavity, collection channels and a secure discharge route. The membrane creates the cavity, while Waterguard, Floor Drain, outlets and pumps manage the water after it enters. The product page identifies CM8 for systems designed to BS 8102:2022 and capable of contributing to Grade 3 conditions when the complete design is appropriate. Type C protection differs from bonded tanking because it does not rely entirely on adhesion to the substrate. However, it requires ongoing access and maintenance, especially where mechanical pumping is essential to keep the space dry.

Q) What are the main advantages of buying Wykamol CM8 as a kit?

A) Buying Wykamol CM8 as a kit brings together compatible core components and simplifies ordering for a measured installation. The package includes the clear membrane, purpose-made sealed brick plugs, double-sided butyl lap tape and a correctly sized drill bit, reducing uncertainty over basic product compatibility. CM8 can be installed on suitable damp or contaminated substrates with less preparation than many fully bonded tanking systems, and the membrane itself requires no curing time. The clear sheet helps installers see the background when aligning, drilling and fixing. Three kit sizes provide flexibility for small and larger projects. Nevertheless, the kit’s convenience does not replace project design, drainage, additional detailing accessories, suitable finishes, testing or a planned maintenance arrangement.

Q) Where can the Wykamol CM8 Waterproof Membrane Kit be used?

A) The Wykamol CM8 Waterproof Membrane Kit can be used on suitable walls and floors in domestic or commercial basements, cellars, plant rooms, underground stores, retaining structures, tunnels and vaulted spaces. It is useful in refurbishment projects where masonry is persistently damp, affected by salts or unsuitable for direct decorative finishes. CM8 may also be considered above ground for residual dampness, penetrating moisture or contaminated backgrounds, provided avoidable defects are corrected wherever practical. The product is not a universal treatment for every damp problem. Groundwater risk, structural condition, drainage capacity, room use and finishing requirements must be assessed before installation. Complex, high-risk or habitable below-ground schemes should involve a competent waterproofing design specialist.

Q) Can Wykamol CM8 help create a habitable basement or Grade 3 environment?

A) Wykamol CM8 can contribute to a system designed for Grade 3 conditions, where water penetration and dampness are unacceptable, as is commonly required for habitable basements. The membrane isolates the internal construction from the damp structure and guides incoming water towards drainage. It cannot independently guarantee Grade 3 performance, because the result depends on the structure, sealed details, channel capacity, discharge route, pumps, alarms, power resilience, ventilation and maintenance. The product information also notes that where Grade 3 waterproofing is required and a below-ground wall retains more than 600mm of ground, combined protection with Type A or Type B waterproofing may be required. Project-specific building-control and warranty requirements should therefore be confirmed before work begins.

Q) Can the Wykamol CM8 Waterproof Membrane Kit be used on walls and floors?

A) Wykamol CM8 is suitable for both wall and floor applications, although the fixing and finishing methods differ. On walls, the studs face the substrate and the membrane is secured into sound masonry with sealed CM Brick Plugs. On floors, it is normally loose-laid with the studs facing down towards the prepared slab or screed. Floor sheets must be sealed together and integrated with the wall membrane, perimeter channel and sump or outlet details. The membrane then needs a compatible load-spreading build-up, such as suitable closed-cell insulation and flooring or an appropriately designed screed. In both locations, water must have an unobstructed route to drainage, and all joints, penetrations and transitions must remain continuously sealed.

Q) Which backgrounds are suitable for installing Wykamol CM8?

A) Wykamol CM8 can be installed over stable concrete, brickwork, blockwork, stone, masonry, sound render and sound screed, provided the background can accept the intended fixings and suits the drainage and finishing design. Loose plaster, weak render, friable masonry, defective screed, severe depressions and sharp projections should be removed or repaired. New concrete floor bases should be suitably flat; the product information specifies no more than 5mm deviation beneath a 3000mm straightedge. Although CM8 generally needs less surface preparation than bonded tanking, the substrate must not damage the membrane or obstruct water movement. Structural instability, active collapse, hazardous contamination and significant movement require proper investigation and remedial work rather than being hidden behind the sheet.

Q) How should a basement be prepared before fitting the Wykamol CM8 kit?

A) Preparation should begin with a survey of the structure, water sources and proposed drainage route. Remove loose finishes, rubble, sharp projections and material that could puncture the sheet or fall into the cavity. Repair unstable areas, large holes and severe irregularities with a compatible product, allowing wet repairs to reach the required condition. Brush away visible mould or masonry fungal contamination and apply a suitable biocide; suspected dry rot needs separate specialist assessment. Concrete affected by free lime, efflorescence or dust may require Wykamol Anti-Lime Sealer to reduce deposits within channels. Leaking plumbing, defective gutters, poor pointing, high external ground levels and other avoidable moisture sources should also be corrected wherever practical before the membrane is enclosed.

Q) How is the Wykamol CM8 membrane installed on a basement wall?

A) Position Wykamol CM8 with the studs against the wall and its smooth face towards the room. Plan the sheet orientation, flange locations, lap direction, fixing lines, drainage termination and final lining before cutting. Hold the membrane tightly into corners without stretching, creasing or bridging it. Drill through the centre of selected studs into sound masonry using the supplied 10mm bit, keeping dust out of the cavity and channel. Insert each CM Brick Plug and drive it home until the rubber washer sits flat and is evenly compressed. General fixing centres should not exceed 600mm unless closer spacing is required. Finally, seal all overlaps, penetrations and junctions and inspect the entire wall before covering it.

Q) How is Wykamol CM8 installed across a basement floor?

A) Before floor installation, ensure the slab or screed is stable, clean and free from oil, loose debris, ridges and sharp projections. Apply an anti-lime treatment where required and allow repairs or treatments to reach the condition stated in their instructions. Roll out Wykamol CM8 with the studs facing down, then cut it neatly around walls, columns, channels, sumps and unavoidable services. Overlap flanged edges, place Wykamol Membrane Sealing Tape inside each clean, dry lap and compress the joint continuously. Connect the floor sheet to the wall membrane and drainage details without blocking water entry into Waterguard. Protect the completed membrane from tools, rubble, concentrated loads and site traffic until the permanent floor build-up is installed.

Q) How far apart should Wykamol CM Brick Plugs be installed?

A) The product guidance states that standard wall fixings should generally be no more than 600mm apart, unless the substrate, membrane layout, board sizes or selected finish requires closer centres. The page also gives approximately five plugs per square metre as a general guide for non-meshed membranes, but the actual calculation should follow the project layout. Extra restraint may be needed at sheet edges, openings, corners, vaults and irregular surfaces. Fixings must pass through the centre of a membrane stud and enter sound material. Coordinate plug rows with battens, brackets or board supports so later trades can use the sealed plug cores. Never reduce the specified number of fixings merely because the selected kit contains fewer plugs than the layout requires.

Q) How are Wykamol CM8 membrane joints and overlaps sealed?

A) Use the flat flange along the edge of Wykamol CM8 wherever possible. Apply the supplied 28mm-wide Wykamol Membrane Sealing Tape inside the overlap, align the adjoining sheet and press or roll the entire joint firmly. Both membrane faces must be clean, dry and free from dust, grease and condensation. On vertical joints, position each new sheet so the lap directs water into the cavity; at horizontal joints, place the lower sheet in front of the upper one. Non-flanged stud-to-stud joints may require Wykamol Sealing Rope and a specified compatible overlap. Wider Corner Strip Tape can reinforce difficult or high-risk details, but it should not substitute for a correctly formed primary joint beneath it.

Q) How should corners, reveals and awkward shapes be detailed with CM8?

A) Fit CM8 tightly into internal and external corners so the sheet forms a defined angle rather than bridging an unsupported hollow. Retain a continuous fold where it can be made without distorting or tearing the studs. If cutting is unavoidable, seal the resulting joint using the appropriate combination of Membrane Sealing Tape, Sealing Rope, Corner Strip Tape and a purpose-cut membrane patch. Door and window reveals, columns, steps, returns and three-dimensional junctions should be planned before the main sheets are cut. Avoid creating bulky layers that cannot be fully compressed. Every cut edge and concealed detail should be accessible for inspection, and photographs or marked no-fix zones should be retained to prevent later drilling through vulnerable areas.

Q) Does the Wykamol CM8 kit require Waterguard drainage or a sump?

A) Wykamol CM8 requires a reliable, maintainable route through which water can leave the cavity. Wykamol Waterguard is commonly positioned at the wall-to-floor junction to collect water from behind the wall membrane, while Floor Drain can provide perimeter or cross-floor collection beneath the floor build-up. If site levels allow, these channels may discharge through a secure gravity outlet. Otherwise, they normally feed a correctly sized sump-and-pump arrangement. Channels, outlets, sumps and pumps are not included in the standard kit. The design must account for anticipated inflow, lift, pipe resistance and consequences of failure. Inspection points, alarms, secondary pumps and backup power should be included where the assessed risk justifies them.

Q) How should pipes and cables passing through Wykamol CM8 be sealed?

A) The safest approach is to minimise penetrations by placing services on the room side of the membrane or within a planned service zone. Where a pipe, cable, conduit or duct must pass through CM8, make the smallest neat opening possible without tearing or excessively distorting the sheet. Form a continuous waterproof seal using compatible Wykamol Sealing Rope, Membrane Sealing Tape, Corner Strip Tape, a membrane patch or a purpose-made collar or sleeve. Clean and dry both the membrane and service surface before applying butyl products. Allow for vibration, thermal movement and future maintenance. Floor penetrations demand particular care because an incomplete seal can admit water directly into insulation, screed or finished flooring without immediate visible warning.

Q) Can the Wykamol CM8 membrane be fitted to vaults or soffits?

A) Wykamol CM8 can be fitted to vaulted, arched or sloping underground surfaces where the sheet can be securely supported and water can drain continuously to a designed collection point. The fixing density, joint direction and sheet sizes should prevent sagging, bridging and pockets that could retain water or sediment. Washers must sit flat, or a specified Sealing Rope detail should be used where this is impossible. A flat below-ground soffit is an important restriction: CM8 should not be installed unless the soffit has a reliable minimum slope of 10% towards drainage. Without that fall, water may pond behind the membrane, load the fixings and place excessive stress on joints and terminations.

Q) What tools and additional products may be needed to fit the kit?

A) Typical tools include an SDS Plus hammer drill, the supplied 10mm masonry bit, spare bits, a rubber or club hammer, sharp utility knife, tape measure, long level, straightedge, marker, clean cloths, pressure roller and effective dust extraction. A laser level can help set out fixing rows, channels and floor levels. Project-specific accessories may include extra sealed plugs and tape, Wykamol Sealing Rope, Corner Strip Tape, Fibre Tape, patches, pipe collars, Waterguard, Floor Drain, swept corners, T-pieces, outlets and jetting eyes. Pumped systems also need a sump, correctly selected pumps, valves, alarms and possibly backup power. All critical components should be available before installation begins so unfinished joints are not left vulnerable.

Q) Does Wykamol CM8 need to cure or dry before it is covered?

A) Wykamol CM8 itself does not require curing because it is a prefabricated HDPE sheet that is mechanically fixed to walls or loose-laid over floors. Follow-on work can generally begin once the membrane, joints, fixings, penetrations and drainage connections have been inspected and tested. This can shorten the programme compared with some wet-applied waterproofing systems. However, materials used elsewhere still have their own curing or moisture limits. Repair mortars, anti-lime treatments, screeds, plasters and adhesives must reach the condition specified by their manufacturers. The product information calls for atmospheric relative humidity below 70% during relevant wet finishing work and screed moisture below 75% relative humidity before impermeable floor coverings are installed.

Q) Can plaster or render be applied directly to Wykamol CM8?

A) Conventional plaster or render should not be applied directly to Wykamol CM8 because it is a clear, non-meshed membrane and does not provide the necessary key for a wet finish. It should instead be protected by a compatible independent frame, battened dry-lining system, blockwork lining or another designed finish. On suitable, reasonably flat walls, an approved dot-and-dab arrangement may use the serrated plug heads as controlled adhesive points where the specification permits. Adhesive should not simply be placed on unsupported membrane. Suitable battens or brackets may be fixed into existing plug cores with controlled-length 5mm No.10 screws that cannot pass through the plug. Where direct plastering is required, a purpose-designed meshed cavity-drain membrane should be specified.

Q) Which floor finishes can be installed over Wykamol CM8?

A) Wykamol CM8 can sit beneath several compatible load-spreading floor constructions. The product page describes a floating arrangement using suitable closed-cell insulation followed by tongue-and-groove flooring, with a 10mm perimeter expansion gap unless the chosen floor system requires otherwise. Another option is a conventional sand-and-cement screed of approximately 65mm where the structure and specification permit it. High-load insulating drainage boards may also be incorporated into an engineered build-up. Whatever finish is selected must distribute imposed loads, protect the studs and preserve required drainage routes. Screed, adhesive or debris must not enter channels or access points. Impermeable coverings should be delayed until the supporting screed reaches the specified moisture condition, and sump covers must remain accessible.

Q) What are the main technical specifications and approvals for Wykamol CM8?

A) Wykamol CM8 is a clear HDPE membrane weighing approximately 0.5kg/m², with a stated sheet thickness of 0.45mm and 7mm stud height, although it is marketed as an 8mm-class product. Published data records a watertightness pass at 60kPa for 24 hours under EN 1928, tensile strengths of 416N in the machine direction and 488N across it, static-load resistance above 20kg and compressive strength of 180kN/m². Its working temperature range is stated as -50°C to +80°C, with a 126°C softening temperature and Class E reaction to fire. The membrane is covered by BBA Agrément Certificate 18/5595 and identified for Type C designs to BS 8102:2022.

Q) How durable is the Wykamol CM8 waterproofing membrane?

A) The published product information gives Wykamol CM8 a life expectancy equivalent to the lifetime of the structure when it is stored, installed and protected in accordance with the technical recommendations. HDPE provides resistance to water, salts, roots and common contaminants, making the membrane suitable for demanding below-ground environments. This durability statement applies to the membrane material and does not mean that the complete waterproofing system can be ignored. Long-term success also depends on intact joints, sealed penetrations, protection from later punctures and continuing operation of channels, outlets and pumps. Rolls should be protected from prolonged sunlight, excessive heat, flames and physical damage, while crushed studs, distorted flanges or damaged sections should be rejected or properly repaired before concealment.

Q) What maintenance does a completed Wykamol CM8 system require?

A) The protected CM8 sheet normally needs little direct maintenance, but all connected water-management components must remain accessible and serviceable. Waterguard and Floor Drain should be inspected and flushed through flexible or extended jetting eyes at intervals appropriate to the site’s water, lime and sediment risk. Longer channel runs may use extended access points at approximately 10m to 12m intervals where suitable. Sumps should be cleaned, pumps and floats operated, non-return valves checked and discharge pipework examined. High-water alarms, secondary pumps, batteries and telemetry should also be tested where fitted. Keep drawings, photographs and no-fix zones so future contractors do not puncture the membrane, block channels or permanently conceal inspection points and sump covers.

Q) Does Wykamol CM8 stop condensation, mould or every type of damp?

A) Wykamol CM8 manages water and moisture entering through the building structure, but it does not remove water vapour produced inside the finished room. Cooking, showering, drying clothes, occupation and insufficient heating can still cause condensation and mould on cold surfaces. A completed basement therefore needs an appropriate insulation, heating and ventilation strategy, including mechanical extraction or whole-room ventilation where required. CM8 may isolate finishes from damp or salt-contaminated masonry, yet leaking plumbing, defective rainwater goods, poor pointing and other avoidable sources should still be repaired. Visible moisture should be investigated rather than automatically blamed on either condensation or membrane failure. Humidity, surface temperatures, channels, pumps, joints, penetrations and discharge arrangements may all require checking.

Q) What are the main limitations of the Wykamol CM8 Waterproof Membrane Kit?

A) The Wykamol CM8 kit is not a stand-alone barrier capable of resisting hydrostatic pressure without functioning drainage and safe discharge. It does not include Waterguard, Floor Drain, sumps, pumps or every accessory needed for corners and penetrations. The non-meshed membrane cannot receive direct plaster or render, and it should not line a flat below-ground soffit unless a reliable minimum 10% fall leads to drainage. CM8 cannot correct structural instability, active movement, hazardous contamination, dry rot or avoidable building defects. Butyl joints need clean, dry surfaces, while installed membrane requires protection from punctures, prolonged sunlight, excessive heat and flame. Habitable, complex, pumped or high-risk projects need competent design, installation, inspection and continuing maintenance.

Q) What practical tips help achieve a reliable Wykamol CM8 installation?

A) Plan the complete water route before cutting or drilling, including sheet direction, fixing rows, Waterguard levels, outlets, sump position, service entries, access points and final finishes. Measure overlaps and wastage separately from gross membrane area, and order extra plugs, tape or detailing products where the layout requires them. Keep all butyl-jointed surfaces clean and dry, control drilling dust and compress every lap along its full length. Fix through stud centres and use existing sealed plug cores for approved secondary fixings with carefully controlled screw lengths. Before concealment, inspect for punctures, loose plugs, damaged washers, bridged corners and unsealed penetrations. Flush the channels, test pumps and alarms, photograph critical details and give the owner a realistic maintenance schedule.

Technical Data Sheet

Declaration of Performance (DoP)

BBA Certificate