Wykamol CM3 Waterproof Membrane Kit

Health & Safety And Installer Competency

Wykamol CM3 forms part of a specialist structural waterproofing system and should be designed and installed by competent people experienced in cavity drain membrane work. Follow the current instructions for the membrane, every included or additional ancillary, the project waterproofing design and applicable health-and-safety requirements.

Before work begins, confirm the retaining structure, expected water conditions, internal environmental grade, drainage route, gravity outlet or sump-and-pump position, pump duty, discharge arrangement, ventilation strategy, final finishes and future maintenance access. Survey structural defects, contamination, biological growth and hidden services so necessary repair or specialist treatment is completed before concealment.

Wear suitable gloves, eye protection and safety footwear. Use appropriate dust extraction and respiratory protection during drilling and substrate preparation. Provide correctly erected access equipment for high walls, arches and vaults, and keep the area well lit and clear of loose rolls, open channels, trailing cables and trip hazards.

Scan for electrical cables, gas pipes, water services and structural hazards before drilling. Control knives, SDS drills, hammers, mallets and hot-air equipment carefully. Controlled warmth may assist membrane drying and butyl adhesion, but CM3 and the supplied Corner Strip Tape must never be overheated or exposed to flame.

System Design Principles

CM3 does not resist hydrostatic pressure as a standalone sheet. Its studded membrane, sealed wall fixings, taped butt joints and drainage components create a depressurised cavity that accepts and controls water entering through the structure. The quantity of ingress must remain within the designed capacity of the cavity, Waterguard, outlet, sump, pumps and discharge pipework.

The waterproofing designer should assess groundwater, retaining conditions, construction type, permeability, wall and slab junctions, movement joints, cracks, service penetrations, slab levels, intended room use and the consequence of failure. Consider combined waterproofing protection where the site risk, construction or required resilience makes one form of protection insufficient.

Every part of the membrane cavity must connect continuously to drainage. Wall CM3, floor CM3, Waterguard, Floor Drain, outlets, sump chambers and discharge routes should form one coordinated path without backfalls, trapped zones, sealed pockets or details that direct water onto vulnerable joints. The shallow 3mm cavity makes preparation and cleanliness especially important.

Where pumping is necessary, assess duty and standby pumps, electrical supplies, high-water alarms, battery back-up, telemetry and safe discharge according to risk. The receiving drain must accept the design flow without surcharging, freezing or returning water towards the protected structure.

For above-ground damp-proofing, diagnose and address avoidable moisture sources before CM3 is installed. Coordinate any required remedial DPC, masonry treatment, dry lining, ventilation and thermal design so the membrane does not conceal active defects or transfer moisture into adjacent untreated construction.

Suitable Substrates And Finishes

CM3 must be installed against a background stable enough to receive the selected fixing and support the completed construction. Resolve active structural movement, collapsing masonry, hazardous contamination and defects requiring engineered repair before the membrane is installed.

Preparation Of Walls, Floors And Soffits

Complete a specialist survey and remedy major causes of damp or water ingress that can reasonably be corrected. Repair structural defects, leaking services, external drainage faults and defective rainwater goods, and specify any separate rising-damp or timber treatment only after the moisture mechanism has been diagnosed.

Remove unsound plaster, render and screed. Stiff-brush or vacuum the background to remove loose material, laitance, salts, dust, mould, adhesive and organic debris. Sound existing render may remain where the survey and fixing design accept it, but friable or poorly bonded layers must not retain plugs or support finishes.

Treat appropriate biological contamination with Wykamol Microtech Masonry Biocide in accordance with its separate label and instructions. Active dry rot, wet rot, timber decay or insect attack requires specialist investigation and a complete remedial specification; covering affected material with CM3 is not an acceptable treatment.

Make good severe depressions, open joints and unstable areas with Wykamol HydraDry Universal Mortar or a compatible 3:1 sand-and-cement mix incorporating Wykamol RenderProof where specified. Where a board finish will be laid directly above CM3, the supporting concrete base must not deviate by more than 5mm beneath a 2m straightedge. Allow repair and levelling products to reach their required condition before covering.

Apply Wykamol Anti-Lime Sealer to suitable concrete where free lime or dust could migrate into the cavity and drainage system. Keep every surface and Waterguard route free from mortar, drilling debris and sharp projections because obstruction or puncture can compromise the shallow 3mm cavity.

Anti-lime sealer being applied to prepared concrete before installation of Wykamol CM3 Waterproof Membrane.

Tools And Ancillary Products Required

The kit contains one or two 10mm x 160mm SDS Plus masonry drill bits according to kit size. Other typical equipment includes a tape measure, straightedge, spirit or laser level, marker, sharp utility knife, scissors or shears, suitable SDS hammer drill, club hammer or mallet, hand roller, clean cloths, stiff brush, vacuum or dust extraction, and controlled hot-air equipment where gentle drying or improved butyl tack is necessary. Vaults and high walls require suitable access equipment.

Set out all CM3 rolls, CM Brick Plugs & Seals, Corner Strip Tape, additional Wykamol Sealing Rope, compatible detailing tape, Waterguard components, preparation products and protection materials before starting. Confirm that every calculated quantity matches the drawings and expected waste. Do not substitute generic tapes, mastics or unverified fittings for a specified waterproofing detail.

Keep tools clean and serviceable. Dull blades can tear CM3, worn drill bits can oversize fixing holes, and contaminated rollers or cloths can impair tape adhesion. Apply firm, even pressure to every butyl seal. Use heat only to assist drying and tack; excessive temperature can distort studs or damage the membrane and tape.

Drainage Requirements

Every below-ground CM3 installation must include a dependable method of disposing of water collecting behind or beneath the membrane. Floors need a suitable outlet and effective route towards it, or a Wykamol Waterguard perimeter system connected to an approved gravity discharge or correctly sized sump-and-pump arrangement.

Wykamol Waterguard is normally positioned at the wall-to-floor junction, while Wykamol Floor Drain can provide cross-floor routes, threshold details or connections to a central sump. The layout must receive water from every membrane cavity and vulnerable structural junction without requiring water to cross unplanned obstructions or sealed zones.

Provide accessible inspection and jetting points at suitable locations, including changes of direction and longer channel runs. Access covers must remain reachable after screed, flooring, dry lining and joinery are completed. Record each location before concealment and include it in the owner’s waterproofing and maintenance information.

Where pumps are required, calculate inflow, duty point, static head, friction loss, discharge distance and chamber volume. Provide redundancy, alarms, power-loss resilience and telemetry where the risk assessment requires them. The final discharge must be lawful, dependable and arranged so water cannot return towards the building.

Wykamol Waterguard Channel positioned at the wall-to-floor junction to collect water from behind Wykamol CM3 Waterproof Membrane, with the specified compatible sealing and insulated floor build-up maintaining continuity to the drainage system.

Wykamol Waterguard And Floor Drain Preparation And Installation

Form the Waterguard route at the wall-to-floor junction in accordance with the current Wykamol channel instructions and project drawings. The supporting bed must be stable and level, and the channel must not be distorted or obstructed by mortar, debris or uneven infill. Position the upstand against the wall-membrane detail so collected water can enter the channel freely.

Join channel lengths with the correct Wykamol components. Use Swept Corners at 90° direction changes, T-Pieces where perimeter and cross-floor runs meet, and Floor Drain where an upstand-free channel is required. Connect the selected 50mm Channel End Outlet or Universal Channel Outlet to approved pipework leading towards the sump, gully or gravity discharge.

Install Flexible or Extended Jetting Eyes wherever required by the maintenance design, ensuring their covers remain reachable through the finished construction. Keep channel interiors clean and check that each fitting maintains an uninterrupted flow path. Do not use adhesive, foam or improvised fittings that create internal lips or can detach later.

Before concealment, flush Waterguard with clean water and verify free flow to the outlet or sump. Inspect every joint, corner, access point and discharge connection, then photograph and record the installed route. Where pumps are fitted, test normal operation, alarm function, back-up provision and discharge under controlled conditions.

Wall Installation

CM3 may be installed vertically or horizontally. Measure the wall and cut the membrane on a clean, protected surface using a sharp knife, scissors or shears. Position the sheet with the studs towards the wall and the flat face towards the room, keeping it level and tight into corners without stretching, bridging or distorting the stud profile.

Begin near the top and install enough initial fixings to support the sheet before completing the selected pattern. Fit the supplied 10mm x 160mm SDS Plus bit in a suitable drill, then drill centrally through a CM3 stud into sound masonry to the depth required by the 10mm x 60mm Wykamol CM Brick Plug. Control drilling dust and avoid holes between studs.

Insert a supplied Wykamol CM Brick Plug & Seal and drive it fully home so its rubber washer compresses evenly against the membrane. Reject loose, damaged or poorly seated fixings. Where a plug without a seal and Wykamol Sealing Rope arrangement is specified, form a continuous butyl ring around the plug and compress it into a watertight gasket.

Continue CM3 into ceiling voids and down to the floor or drainage detail wherever possible. Return the sheet sufficiently onto adjacent walls to isolate the final lining, and plan openings before fixing. Keep electrical points, cables, pipework and switches on the dry side wherever practicable.

Wall Fixing Centres And Internal Finishes

Fixing density depends on the substrate and selected internal finish. For preservative-treated timber battens, BBA guidance gives maximum centres of 400mm vertically and 600mm horizontally. Proprietary metal or independent-frame systems may require fewer membrane fixings, but enough must hold CM3 reasonably tight, particularly around corners, openings and junctions. Barrel-vault details may require tighter project-specific restraint to prevent sagging.

Use preservative-treated battens at least 25mm x 38mm, with 25mm x 50mm often providing better support at board edges. Fix suitable 5mm (No. 10) self-tapping screws into the central cores of CM Brick Plugs & Seals so no second hole is formed through CM3. Control screw length and tightening so the plug remains secure and the membrane is not punctured.

Independent floor-supported frames do not require a standard membrane-fixing grid, but enough plugs must hold CM3 reasonably tight at corners, openings and junctions. Compatible proprietary metal systems and correctly restrained internal masonry linings may also be used where their loads and ties are designed without uncontrolled penetrations.

Fix plasterboard or approved lining boards so screws and nails remain within the batten depth. Keep services in front of CM3 and support heavy fittings from predetermined battens or designed structural supports. Any exceptional fixing through the membrane requires a specific load-bearing and waterproofing detail.

Wykamol CM Brick Plugs & Seals fixing Wykamol CM3 to the wall, with fixing centres set to suit the internal finish, typically 600mm vertically and 400mm horizontally for timber battens.

Jointing And Sealing

Wykamol CM3 is non-flanged. Position adjoining sheets edge to edge as a close, accurately aligned butt joint. Keep cut edges straight and free from open gaps, distorted studs or sheet overlap. Clean and dry the flat membrane face on both sides of the joint before applying tape.

Centre the supplied 150mm Wykamol Corner Strip Tape over the joint so approximately equal width bonds to each sheet. Apply it progressively using firm palm or roller pressure, removing wrinkles, bridging and trapped air while maintaining full contact across both CM3 faces.

In cold or damp conditions, gently dry the HDPE with controlled hot air and warm the butyl only enough to improve tack. Never seal over visible water, dust, mortar, grease or loose material. Use continuous tape lengths wherever practicable and form unavoidable tape end-joints in accordance with the current Corner Strip Tape instructions.

Straight joints may run vertically or horizontally, but unnecessary joints should be avoided. The supplied Corner Strip Tape length may not cover every joint and detail, so complete a take-off and obtain additional rolls where necessary. Inspect each seal before concealment and repair damage with compatible CM3 and the specified Wykamol butyl products.

Wall-To-Floor Junction And Waterguard Integration

The wall-to-floor junction must transfer water from behind CM3 into Waterguard without leaving an unprotected gap or sealed pocket. Position the wall membrane and channel upstand to the approved detail, then clean and dry the receiving surfaces before applying Wykamol Corner Strip Tape.

Where CM3 continues across the floor, turn the floor membrane up at the perimeter and seal it to the wall membrane or Waterguard upstand as specified. Form corners neatly and avoid bunching the sheet, blocking channel openings or pulling tape across unsupported voids.

Where a deep floor construction could allow condensation to run down the room-facing side of the wall membrane above the Waterguard upstand, Newton CDM Condensation Strip may be incorporated only where the waterproofing designer has confirmed compatibility with the Wykamol system. The detail must collect room-side condensation without obstructing water entering Waterguard from the structural side.

Before floor finishes are installed, introduce controlled clean water behind the wall membrane and confirm that it enters Waterguard and reaches the gravity outlet or sump. Rectify slow flow, leakage, trapped sections and incomplete seals before concealment.

Floor Installation

Provide the designed outlet, fall and Waterguard arrangement before laying CM3. The concrete base must be stable, clean and free from sharp projections. Where a board finish will lie directly over the membrane, prepare the floor so it does not deviate by more than 5mm beneath a 2m straightedge.

Roll CM3 across the floor with the studs facing down. Cut sheets neatly around perimeters, columns, channels and unavoidable services without stretching or crushing the studs. The floor membrane remains loose laid and must never be fixed through to the slab.

Bring adjoining floor sheets together as close butt joints without overlapping CM3. Centre 150mm Wykamol Corner Strip Tape over each joint, press it firmly across its full width and maintain accurate edge alignment while sealing. The finished membrane must remain continuous and free from open edges, wrinkles or trapped debris.

Protect CM3 promptly using a compatible load-spreading floor construction. Options may include loose-laid tongue-and-groove board, Newton Fibran XPS 500-C or Wykamol High Load within an approved build-up, supported timber flooring, or project-specified screed or concrete. Provide the required perimeter expansion gap, check imposed loads and prevent all subsequent fixings from puncturing the membrane.

CM3 may be laid over suitable new concrete once it is safely walkable, allowing the protected floor construction to proceed without waiting for the concrete to reach decorative-floor moisture limits. Every screed, adhesive, board and final finish must still comply with its own substrate-moisture, curing and installation requirements.

Vaulted Soffit Installation

CM3 may be installed to suitable arched or vaulted ceilings where the structure provides a dependable continuous fall to drainage. Survey the curve, end walls, joint positions and outlet route before cutting so the membrane follows the background without excessive tension, open folds or sagging pockets.

Position the studs towards the soffit and secure the membrane using additional Wykamol CM Brick Plugs Without Seals. Form a continuous ring of Wykamol Sealing Rope around each plug and drive the fixing firmly enough to compress the butyl into a watertight gasket. Do not use the supplied washer-sealed plugs where the curved surface prevents an even seal.

Where separate sections meet across the vault, form a close butt joint and seal it centrally with 150mm Wykamol Corner Strip Tape. Plan shaped cuts carefully, minimise joint numbers and install sufficient fixings to prevent sagging or pockets capable of retaining water and debris.

At each end wall, turn the vault membrane down by at least 200mm. Mitre only as necessary to follow the curve, seal each cut with compatible tape or rope, and install the wall membrane in front of the turned-down soffit sheet so water continues towards the designed collection route.

Flat Soffit Restrictions

Do not install CM3 to a flat retaining soffit. Vaulted, arched or sloping soffits must provide a dependable minimum 10% fall so water behind the membrane moves towards the designed drainage point rather than ponding against the sheet, fixings or taped joints.

Where the soffit does not provide this fall, the waterproofing designer must specify another solution. Do not attempt to create drainage by allowing CM3 to hang loosely, because sagging forms uncontrolled pockets and places additional stress on fixings and joints.

Check the complete width and length of every arched, vaulted or sloping soffit. Local depressions, beams, ribs, abutments and changes of direction can interrupt the route even where the general geometry appears suitable. Resolve each obstruction and connect every cavity to safe drainage before installing finishes.

Door Reveals, Corners And Junction Details

Run CM3 continuously around internal and external corners where it can be folded neatly without excessive distortion. Form a square crease and fix the membrane tightly into the angle so the lining remains straight and the cavity does not bridge across the corner.

If CM3 becomes misshapen around a return, stop at the corner and begin a new sheet rather than forcing the fold. Bring the edges together as a close butt joint and seal them with 150mm Corner Strip Tape. Use Wykamol Sealing Rope where a three-dimensional detail cannot make continuous contact with flat tape.

Where possible, install CM3 across window openings and trim the aperture afterwards so the main sheet remains continuous. Seal exposed perimeters using the specified combination of Wykamol Membrane Sealing Tape, Wykamol Sealing Rope and Corner Strip Tape. At doors or fixed obstacles, bring CM3 accurately to the perimeter and seal the junction with equal care.

Coordinate thresholds with Waterguard Floor Drain, perimeter channel or another compatible continuity detail before membrane fixing begins. Avoid isolated cavities beside frames and never leave an open reveal or return through which water can bypass CM3 and reach the dry lining.

Protrusions Through Wykamol CM3

Avoid membrane penetrations wherever practical and route pipes, cables, conduits, sockets and controls on the dry side. Where a penetration cannot be avoided, establish its location before cutting and keep the opening small, regular and suitable for the selected sealing detail.

For floor services, trim CM3 closely around the pipe or conduit and fill the remaining gap completely with Wykamol Sealing Rope. Where necessary, add a compatible CM3 patch, seal it to the service with rope and seal its outer edge using Wykamol Membrane Sealing Tape or Corner Strip Tape.

Use suitable proprietary collars or sleeves for larger, grouped, moving, hot or irregular services where a rope-and-patch arrangement cannot provide durable continuity. Confirm compatibility with the service material, operating temperature, expected movement and future replacement method.

Exceptional structural fixings through a lined wall require a predetermined load-bearing and waterproofing detail. Support heavy objects from designed battens or structural anchors wherever possible. Pack and seal every unavoidable hole through CM3 using compatible flexible butyl products before it is concealed.

Protection Of Wykamol CM3 After Installation

Protect CM3 from sharp tools, dropped fixings, masonry fragments, ladders, wheelbarrows and concentrated foot traffic as soon as each area is complete. A concealed tear, displaced tape edge or crushed drainage path can compromise the finished system even where most of the visible membrane remains intact.

Keep prolonged ultraviolet exposure, high temperatures, ignition sources, open flame and incompatible chemicals away from stored or installed CM3. Prevent following trades from dropping mortar, screed, plaster or drilling debris into the membrane cavity, Waterguard channel, sump chamber or inspection ports.

Coordinate subsequent work through one responsible person. Electricians, plumbers, joiners, dry liners and floor installers must understand that they cannot drill, nail or screw through CM3 without an approved sealed detail. Mark restricted zones and provide predetermined battens, supports and service routes before finishes are closed.

Where temporary protection board is used, ensure it does not crush the studs or obstruct drainage. Remove it carefully, inspect the entire membrane and clean Waterguard immediately before installing the permanent wall or floor protection.

Ventilation And Humidity Control

CM3 has high resistance to vapour diffusion. When positioned on the cold side of insulation, it can increase interstitial-condensation risk unless the complete wall or floor construction and indoor environment are designed correctly. Complete an appropriate BS 5250:2021 assessment and provide a warm-side vapour-control layer where the design requires one.

Habitable basements and Grade 3 spaces normally require planned mechanical ventilation, background heating or another competent environmental-control strategy. Air-change rates, extract locations, make-up air, noise, energy use and controls should suit the occupancy and expected internal moisture generation.

Do not open the membrane cavity directly to the room as an improvised condensation measure. Uncontrolled openings may permit odours, vermin, moisture or water to bypass the intended waterproofing and drainage arrangement.

Monitor relative humidity after completion and address persistent internal sources including wet construction materials, clothes drying, unvented appliances or inadequate extraction. Type C waterproofing manages water from the retaining structure; it does not replace normal control of indoor humidity and air quality.

Inspection Before Finishes

Inspect the complete CM3 installation before dry lining, flooring, screed or concrete conceals it. Confirm that the membrane is correctly orientated, tight to walls and vaults, free from crushed studs, and protected from tears, open edges, unsupported joints or unsealed fixing points.

Check every butt joint, corner, door and window detail, service penetration, wall-to-floor transition and Waterguard connection. Confirm that 150mm Corner Strip Tape is centred across each sheet joint, fully bonded and firmly rolled. Replace any tape contaminated by dust, water, oil or loose material instead of attempting to reuse it.

Vacuum cavity edges and drainage channels. Flush Waterguard and Floor Drain with clean water and verify unrestricted flow to the gravity outlet or sump. Operate pumps, high-water alarms and any back-up system, and ensure discharged water cannot return towards the structure.

Photograph the membrane, channels, outlets, sump, pipework and concealed details. Record dimensions from permanent reference points and complete the installation inspection documentation. Do not approve concealment until every defect is repaired and the tested system performs as intended.

Repairs To Wykamol CM3

Repair all damage before concealment. Clean and dry the affected CM3, trim ragged material where necessary and confirm whether the studs and drainage cavity remain usable. A small clean puncture may be sealed using the appropriate specified Wykamol tape, while a larger tear requires a compatible patch extending well beyond sound membrane on every side.

Use Wykamol Sealing Rope around irregular holes, plug penetrations and three-dimensional details, then secure the repair with Wykamol Membrane Sealing Tape or Corner Strip Tape as appropriate. Apply firm pressure across the complete seal and use controlled warmth only where necessary to dry the surface or improve butyl tack.

Where damage has crushed a significant studded area, affected a critical joint or occurred beside Waterguard, a penetration or wall-to-floor transition, replace the membrane section or obtain a project-specific repair detail. A flat patch that seals the face while obstructing the drainage cavity is unacceptable.

Repeat the relevant inspection and controlled water test after repair. Photograph the completed detail and include its location and repair method in the waterproofing record for future owners and contractors.

Maintenance And Future Alterations

The protected CM3 membrane does not require routine surface maintenance under normal service conditions, but the drainage system supporting Type C performance does. Waterguard, Floor Drain, jetting eyes, outlets, sump chambers, pumps, alarms, back-up power and discharge pipework must remain accessible and receive servicing at the intervals set by the system designer and equipment manufacturers.

Flush channels through the designated access points and remove lime, silt or debris before it restricts flow. Test pumps and float switches, clean sump chambers, operate alarms and verify back-up equipment under controlled conditions. Keep service records and investigate increased pump activity, unusual noise, odour, dampness or changing water levels promptly.

Future shelving, cupboards, skirtings, flooring, services and wall-mounted equipment must not be fixed through CM3 casually. Use recorded battens and designed supports or obtain a waterproofing detail for each new penetration. A small unsealed hole can allow water to bypass the membrane.

Provide the owner with drawings, photographs, test records, component information, access-point locations, pump manuals and maintenance contacts. Any contractor altering the space should review these records before drilling, lifting floors or opening linings.

Key Limitations

• The kit supplies selected membrane installation products only; it does not constitute a complete Type C waterproofing, drainage, discharge, protection or finishing system.
  
  

• CM3 does not resist hydrostatic pressure as a standalone barrier. It requires continuous drainage connected to a dependable gravity outlet or correctly designed sump-and-pump arrangement.
  
  

• The 20m² and 40m² figures are nominal membrane roll areas, not finished installed coverage. Allow for trimming, junctions, details, repairs and reasonable waste.
  
  

• The included 50 or 100 CM Brick Plugs & Seals may not satisfy the actual fixing calculation. Order additional plugs wherever the substrate, finish, fixing centres or vault geometry requires them.
  
  

• The supplied 10m or 20m Corner Strip Tape roll may not cover every butt joint, transition, corner and repair. Calculate the complete measured tape requirement separately.
  
  

• The shallow 3mm cavity must remain clean and unobstructed, making control of drilling dust, mortar, free lime, silt and crushed studs particularly important.
  
  

• Where Grade 3 protection is required and retained ground exceeds 600mm, BBA Certificate 18/5595 requires CM3 to be combined with Type A or Type B protection.
  
  

• CM3 has not been BBA assessed for chemically contaminated brownfield sites; hazardous or unknown contamination requires specialist investigation and project-specific materials assessment.
  
  

• CM3 is non-meshed and must not receive direct plaster or render. Use a compatible protected lining or specify a suitable meshed membrane where a wet finish is required.
  
  

• Do not install CM3 to a flat retaining soffit. Vaulted, arched or sloping soffits require a dependable minimum 10% fall and sufficient sealed fixings to prevent ponding.
  
  

• Floor CM3 must never be punctured by ordinary fixings. Board, insulation, screed and Wykamol High Load constructions require suitable support, drainage and load checking.
  
  

• High vapour resistance can increase condensation risk when CM3 lies on the cold side of insulation; ventilation, heating and BS 5250 assessment remain necessary.
  
  

• Every CM3 sheet-to-sheet joint must be a close butt joint sealed centrally with 150mm Wykamol Corner Strip Tape; adjoining sheets must not be lapped or overlapped.
  
  

• The supplied washer-sealed plugs are intended for suitable wall applications. Curved overhead details may require additional plugs without seals and separately applied Wykamol Sealing Rope.
  
  

• Keep all butyl surfaces clean and dry. Corner Strip Tape and Wykamol Sealing Rope will not seal reliably over dust, grease, standing water, condensation or loose material.
  
  

• Protect CM3 from fire, impact, prolonged ultraviolet exposure, high temperatures and uncontrolled penetrations throughout installation and service.
  
  

• Pumps, alarms, battery back-up and telemetry reduce risk but do not eliminate it. Their capacity, power provision, discharge and maintenance must match the consequences of failure.
  
  

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

Storage And Shelf Life

Store CM3 rolls upright in their original protective wrapping, under cover and on a stable surface. Keep them away from sharp objects, prolonged sunlight, high temperatures, ignition sources and open flame. Do not stack or handle rolls in a way that crushes the 3mm studs, distorts edges or punctures the sheet.

Under normal service conditions, BBA Agrément Certificate 18/5595 states that Wykamol CM3 can provide an effective barrier to salts, liquid water and water vapour for the life of the structure in which it is incorporated. This membrane-specific statement does not establish a combined service life for the complete kit.

Keep Wykamol Corner Strip Tape in its original packaging under clean, dry conditions and protect the butyl face from dust, moisture, heat and deformation. Keep CM Brick Plug sealing washers clean, flat and undamaged. Store drill bits dry and inspect their cutting heads and SDS shanks before use. Each included or additional component remains subject to its own storage, shelf-life and service information.

Other Technical Information

Wykamol CM3 is a clear, non-meshed HDPE membrane with a published unit weight of 0.5kg/m², 0.6mm sheet thickness, 3mm stud height, 20mm stud centres and 2.19 litres/m² air-gap volume. The 20m² kit contains a 2m x 10m roll, while the 40m² kit contains a 2m x 20m roll. Actual coverage must allow for project geometry, detailing and waste.

Published membrane performance includes watertightness at 60kPa for 24 hours to EN 1928, 416N machine-direction and 488N cross-direction tensile strength, static-loading resistance above 20kg and declared compressive strength of 250kN/m². The stated working temperature is -50°C to +80°C and the softening temperature is 126°C.

CM3 is declared as a Type V sheet to BS EN 13967:2012+A1:2017, with Class E reaction to fire to EN 13501-1:2007+A1:2009. These values apply to the membrane product and do not establish the performance of the Corner Strip Tape, plugs, drill bits or completed waterproofing construction.

The 20m² kit supplies 50 sealed CM Brick Plugs & Seals, one 150mm x 10m Corner Strip Tape roll and one 10mm x 160mm SDS Plus drill bit. The 40m² kit supplies 100 plugs, one 150mm x 20m tape roll and two drill bits. These are fixed supply quantities; calculate and order additional materials wherever the project requires them.

The membrane can contribute to a Type C system designed under BS 8102:2022, but successful performance depends on the complete arrangement. Product data and the presence of included fixing products do not replace a site-specific drainage design, competent installation, inspection, commissioning and continuing maintenance.

Q) What is the Wykamol CM3 Waterproof Membrane Kit?

A) The Wykamol CM3 Waterproof Membrane Kit is a convenient package containing the principal products needed to begin installing a low-profile cavity drain or damp-proof membrane. Its central component is clear Wykamol CM3, a non-meshed HDPE sheet with 3mm studs that create a defined space between the substrate and protected internal finish. The kit also supplies sealed wall fixings, wide jointing tape and correctly sized SDS Plus masonry drill bits. CM3 can be used within designed Type C basement waterproofing systems or for suitable above-ground damp-proofing work. The kit simplifies product selection, but drainage, preparation treatments, complex detailing products, internal linings and floor finishes remain project-specific requirements.

Q) What is included in the Wykamol CM3 Waterproof Membrane Kit?

A) Each kit contains one clear Wykamol CM3 membrane roll, Wykamol CM Brick Plugs & Seals, one roll of 150mm-wide Wykamol Corner Strip Tape and either one or two 10mm by 160mm SDS Plus drill bits, depending on kit size. The plugs mechanically secure CM3 to suitable masonry walls and incorporate rubber washers that seal the fixing penetrations. Corner Strip Tape is the principal face-applied product for sealing straight butt joints between adjoining non-flanged CM3 sheets. The package does not include Wykamol Waterguard, floor drainage, outlets, pumps, alarms, preparation products, additional detailing tape, sealing rope, repair materials, insulation, dry lining, screed or decorative finishes.

Q) Which Wykamol CM3 kit sizes are available, and what does each contain?

A) The 20m² kit contains a 2m by 10m CM3 roll, 50 Wykamol CM Brick Plugs & Seals, one 150mm by 10m roll of Corner Strip Tape and one 10mm by 160mm SDS Plus drill bit. The 40m² kit contains a 2m by 20m membrane roll, 100 sealed plugs, one 150mm by 20m Corner Strip Tape roll and two matching drill bits. These areas are nominal roll sizes, not guaranteed finished coverage. Allow for trimming, corners, junctions, penetrations, repairs and reasonable waste. Calculate actual fixing and tape requirements separately, as complex layouts or closer fixing centres may require additional products.

Q) How does Wykamol CM3 manage water and dampness?

A) CM3 separates the protected internal construction from damp, salty or water-affected masonry. Its 3mm studs face the substrate, forming a shallow cavity behind the flat membrane surface. In below-ground Type C waterproofing, water entering through the retaining structure can move within this cavity towards Wykamol Waterguard, a suitable gravity outlet or a correctly designed sump-and-pump system. Above ground, CM3 can isolate compatible dry linings from sound damp or salt-contaminated walls after avoidable moisture sources have been addressed. The membrane also resists water vapour, helping to protect finishes. It does not stop hydrostatic pressure as a standalone sheet, so continuous drainage and dependable discharge are essential below ground.

Q) Is the Wykamol CM3 Waterproof Membrane Kit suitable for Type C waterproofing?

A) Yes. Wykamol CM3 can form the cavity membrane element of a Type C drained protection system designed in accordance with BS 8102:2022. Type C construction accepts that water may penetrate the retaining structure, then controls it within a drained cavity before conveying it to a safe discharge point. The kit supplies CM3, standard sealed wall plugs, butt-joint tape and drill bits, but it is not the complete Type C system. The finished design must also address water risk, collection channels, inspection access, gravity drainage or pumping, alarms, backup measures, discharge pipework, ventilation, finishes and maintenance. Every section of the cavity must connect continuously to the intended drainage route.

Q) Can Wykamol CM3 also be used for above-ground damp proofing?

A) Yes. Wykamol CM3 can be used above ground to isolate compatible dry linings from sound masonry affected by residual dampness or salts, particularly where a non-meshed membrane is appropriate. Before installation, identify and address avoidable moisture sources such as defective rainwater goods, leaking services, bridged cavities, high external ground levels or correctly diagnosed rising damp. Complete necessary repairs and coordinate any separately specified remedial damp-proof course, masonry treatment, ventilation and thermal improvements. CM3 should not simply conceal an active defect or divert moisture into neighbouring untreated materials. Because it is non-meshed, it requires battens, an independent frame, a suitable proprietary lining or internal masonry rather than direct plaster or render.

Q) What projects commonly use the Wykamol CM3 Waterproof Membrane Kit?

A) Typical projects include basement waterproofing, cellar conversions, damp-proofing refurbishments, earth-retained wall linings, concrete floor protection, vaulted cellars and suitable tunnels. The compact 3mm profile is particularly useful where headroom, floor depth or internal space is restricted around staircases, doorways, thresholds and narrow rooms. CM3 may be mechanically fixed to suitable masonry walls, loose-laid over prepared concrete floors or installed to appropriately falling vaults using the correct specialist fixing detail. The kit can support storage, utility or habitable-space projects, but the complete specification must match the intended internal environment. Water risk, retained-ground height, drainage capacity, ventilation, insulation, finishes and consequences of failure all require assessment before installation.

Q) Can Wykamol CM3 be installed on walls, floors and vaults?

A) Yes, although each application requires a different installation detail. On walls, CM3 is positioned with the studs towards the substrate and secured through stud centres using sealed CM Brick Plugs. On floors, it is normally loose-laid studs down over a stable, clean concrete base, joined and connected to the designed drainage route before receiving a compatible load-spreading construction. Vaults and arched soffits require dependable falls, closer fixings and separately sealed plug details to prevent sagging or ponding. Wall, floor and vault membranes must form one coordinated drainage path. The standard kit quantities may not provide all additional fixings, tape, sealing rope, corners or patches needed for a complex three-dimensional installation.

Q) Can the Wykamol CM3 kit help create a Grade 3 habitable basement?

A) Wykamol CM3 can contribute to a complete system designed for a Grade 3 internal environment, where no water penetration is acceptable and appropriate environmental control is provided. The membrane alone cannot deliver that result; drainage, discharge resilience, ventilation, insulation, heating, condensation control, detailing and maintenance must be coordinated with the retaining structure. BBA Agrément Certificate 18/5595 requires CM3 to be combined with Type A or Type B waterproofing protection where Grade 3 protection is required and the below-ground wall retains more than 600mm of ground. The waterproofing designer should establish the required grade, combined-protection strategy, pump resilience, inspection access and consequences of failure before products are ordered or building finishes are selected.

Q) Why choose a 3mm cavity drain membrane?

A) A 3mm stud profile creates a controlled cavity while minimising the loss of usable room space, headroom and floor depth. This makes Wykamol CM3 attractive for restricted basement conversions, low ceilings, stairs, thresholds and narrow passageways. The clear, lightweight sheet is also easier to position and allows substrate features and fixing points to remain visible during installation. The trade-off is that its shallow cavity has less available flow space than a deeper-studded membrane and can be obstructed more quickly by mortar, drilling dust, free lime, silt or crushed studs. CM3 should therefore be selected from a water-risk assessment, with careful preparation, clean drainage routes and dependable maintenance rather than simply chosen for its slim profile.

Q) What are the main advantages of buying the Wykamol CM3 kit?

A) The kit combines a recognised CM3 membrane with purpose-matched Wykamol jointing and fixing products, reducing the risk of ordering unsuitable basic components. Its 20m² and 40m² options provide clear starting quantities, while the supplied 10mm drill bits match the included CM Brick Plugs. The transparent, non-meshed membrane is lightweight, quick to cut and suitable behind several protected lining systems. Its compact studs preserve valuable internal dimensions, and mechanical installation usually avoids the extensive surface preparation demanded by fully bonded tanking. The main ordering advantage is convenience, not completeness: drainage, extra tape and plugs, specialist details, preparation treatments, floor build-ups, finishes and maintenance provisions must still be calculated for the individual project.

Q) What material is Wykamol CM3 made from?

A) Wykamol CM3 is manufactured from clear high-density polyethylene, commonly known as HDPE. The material is waterproof, resistant to water vapour and capable of isolating internal finishes from salts, liquid water and moisture within its certified use. It does not rot and provides a robust membrane at a nominal unit weight of 0.5kg/m². The sheet itself is 0.6mm thick, with formed 3mm studs positioned at 20mm centres. Its clear appearance helps installers see background features and align drilled fixing positions. CM3 must nevertheless be protected from punctures, crushed studs, uncontrolled heat and damaging follow-on work. Unknown or hazardous chemical contamination requires specialist investigation before specification.

Q) How should the substrate be prepared before fitting Wykamol CM3?

A) The background must be structurally sound, stable and free from conditions that could puncture the membrane or obstruct its shallow cavity. Remove loose plaster, render, screed, mortar droppings and sharp projections, then repair severe depressions, open joints and unstable areas with an appropriate specified material. Brush and treat suitable biological contamination with Wykamol Microtech Masonry Biocide, while active dry rot, wet rot, timber decay or infestation requires specialist assessment. Scan for concealed services before drilling. Where boards will lie directly above floor CM3, the supporting concrete base should not deviate by more than 5mm beneath a 2m straightedge. Keep all prepared surfaces and drainage channels clean before covering.

Q) Should Wykamol CM3 be installed vertically or horizontally on walls?

A) Wykamol CM3 may be fixed vertically or horizontally, with the preferred orientation determined by wall height, room geometry, handling and the number of joints created. Horizontal installation can reduce vertical joints, but a full 2m-wide roll becomes heavy and must be kept level while it is unrolled. Vertical drops are lighter and often easier to position accurately, although they usually create more butt joints and increase Corner Strip Tape consumption. Establish a level reference, temporarily hang the first sheet using top fixings and check alignment before completing the fixing grid. Set out corners, reveals, openings, drainage connections and lining supports first so cuts and joints occur in accessible, properly supported positions.

Q) How is Wykamol CM3 fixed to a masonry wall?

A) Position CM3 with the studs against the prepared wall, then drill through the centre of a stud using the supplied 10mm SDS Plus bit. The hole must suit the 10mm by 60mm CM Brick Plug and be cleared of loose drilling dust. Insert the plug and drive it until the fitted rubber washer compresses evenly against the membrane without distorting or crushing the stud. Begin with top fixings to establish a level sheet, then complete the rows at centres required by the internal lining. Keep fixings aligned where they will receive battens. Do not overdrive plugs, drill through flat membrane areas unnecessarily or assume the included quantity is sufficient for every wall finish and substrate.

Q) What fixing centres should be used with Wykamol CM3?

A) Fixing centres are determined by the selected lining, substrate and geometry. Typical timber-batten arrangements use CM Brick Plugs at 600mm vertically and 400mm horizontally, while a compatible fixed metal lining may use 800mm vertically and 600mm horizontally. Vaulted work normally needs tighter spacing, often approximately 300mm around the curve and 600mm along the vault, to prevent sagging. Floor-supported independent frames do not rely on a standard plug grid, although enough fixings are still required to hold CM3 neatly at corners, openings and junctions. The waterproofing and lining specifications take priority. Calculate the actual requirement because the kit’s 50 or 100 plugs may not cover closer centres or complicated layouts.

Q) How is Wykamol CM3 installed on a floor?

A) Establish the drainage layout, outlet and falls before laying the membrane. Prepare the concrete base so it is stable, clean, suitably level and free from sharp projections. Unroll CM3 with the studs facing down, relax the sheet, cut it accurately to the room and form close butt joints between adjoining widths. Seal each joint centrally with 150mm Wykamol Corner Strip Tape, then connect the floor membrane continuously to the wall membrane and Waterguard detail. Protect the completed sheet promptly with the specified load-spreading board, insulation, screed or concrete construction. Never use ordinary fixings through floor CM3, and inspect joints, perimeters, penetrations and drainage flow before they are permanently concealed.

Q) How are joints sealed in Wykamol CM3 membrane?

A) Wykamol CM3 is non-flanged, so adjoining sheets are positioned edge to edge as a close, accurately aligned butt joint. Keep cut edges straight and remove dust, moisture, grease, mortar and loose material from the flat face on both sides. Centre the supplied 150mm Wykamol Corner Strip Tape over the joint, leaving approximately equal contact width on each sheet, then apply it progressively with firm palm or roller pressure. Eliminate wrinkles, bridging and trapped air. Controlled warm air may help dry the HDPE or improve butyl tack in cold conditions, but never overheat the membrane or expose it to flame. Inspect every seal before concealment and repair damage using specified Wykamol products.

Q) How should corners and wall-to-floor junctions be detailed?

A) Corners and wall-to-floor junctions must preserve a continuous route from behind CM3 into the designed collection system. Form internal and external corners neatly without bunching the sheet, crushing studs or pulling tape over unsupported gaps. At floor level, position the wall membrane, floor upstand and Wykamol Waterguard channel to the approved detail, then clean and dry all receiving surfaces before applying Corner Strip Tape. Avoid sealed pockets, backfalls and blocked channel openings that could trap water. The supplied tape roll may not cover every transition, corner, reveal or repair, so complete a measured take-off. Complex junctions may additionally require Wykamol Sealing Rope, Membrane Sealing Tape, patches or a project-specific formed detail.

Q) Does the Wykamol CM3 Waterproof Membrane Kit include drainage?

A) No. The standard kit includes the CM3 membrane, sealed wall plugs, Corner Strip Tape and SDS Plus drill bits, but Wykamol Waterguard, Floor Drain, inspection access, outlets, sumps, pumps and alarms are selected separately. Every below-ground CM3 installation requires a dependable means of collecting and disposing of water from behind or beneath the membrane. This may involve Waterguard at the wall-to-floor junction, cross-floor drainage, an approved gravity discharge or a correctly sized sump-and-pump arrangement. Pumped systems may also need duty and standby pumps, high-water alarms and backup power according to risk. Drainage capacity, maintainability and safe discharge must be established before the membrane is installed, not added as an afterthought.

Q) Is Wykamol Anti-Lime Sealer required before installing CM3?

A) Wykamol Anti-Lime Sealer should be applied to suitable concrete where free-lime leaching, dusting or mineral deposits could migrate into the CM3 cavity or drainage system. This is particularly important with new or lime-releasing concrete because the membrane’s 3mm cavity and Waterguard openings can be restricted by deposits more quickly than deeper spaces. Prepare the concrete and apply the product at the specified coverage in accordance with its instructions before enclosing the surface. Anti-lime treatment is preventive and does not replace accessible drainage, flushing points or regular servicing. Existing lime deposits should be investigated and removed appropriately, while the maintenance plan should include inspection of channels, sumps, pumps and discharge routes for recurring accumulation.

Q) Can the Wykamol CM3 kit be used on vaulted ceilings?

A) CM3 can be installed to suitable arched or vaulted ceilings where the background provides a dependable continuous fall towards drainage. Survey the curve, end walls, joint positions and outlet route before cutting, then position the studs towards the soffit. Vaults require additional Wykamol CM Brick Plugs Without Seals, each bedded against a continuous ring of Wykamol Sealing Rope; standard washer-sealed wall plugs are unsuitable where the curve prevents an even seal. Fixing centres must prevent sagging and pockets that could retain water or debris. Butt joints are sealed with 150mm Corner Strip Tape, and end details must direct water continuously towards collection. Experienced structural waterproofing installation is strongly recommended for overhead work.

Q) How should pipes, cables and other penetrations through CM3 be sealed?

A) Route services on the protected side of CM3 wherever possible because every opening creates a potential route for water to bypass the membrane. Where a penetration is unavoidable, form the smallest practical cut, support the service independently and use a compatible collar, CM3 patch, Wykamol Sealing Rope and specified tape arrangement suited to the service material and anticipated movement. The seal must remain continuous around the complete circumference without obstructing drainage. Avoid grouped penetrations, poorly supported pipes and reliance on decorating caulk, expanding foam or general-purpose tape. Photograph and inspect each concealed detail before closing the lining. Valves, junctions, drainage access, pumps and alarm equipment must remain accessible for maintenance and future replacement.

Q) What wall finishes can be installed in front of Wykamol CM3?

A) CM3 is a smooth, non-meshed membrane and must not receive plaster or render directly. Suitable protected finishes may include plasterboard on treated timber battens, a floor-supported independent dry-lining frame, a compatible proprietary metal lining system or a properly restrained internal brick or block wall. Battens can be secured into the central cores of correctly positioned CM Brick Plugs using suitable 5mm screws, avoiding uncontrolled additional penetrations. Select screw lengths carefully so they remain within the batten and plug detail rather than puncturing CM3. The lining design must also address insulation, condensation risk, fire performance, ventilation and imposed loads. Heavy cupboards or fittings require predetermined battens or independent structural supports rather than casual membrane penetrations.

Q) What floor finishes can be installed over Wykamol CM3?

A) CM3 may receive a compatible load-spreading floor construction after joints, perimeters and drainage connections have been completed and inspected. Depending on the specification, this may include loose-laid tongue-and-groove flooring board, supported timber flooring, suitable high-compressive-strength insulation with board, Wykamol High Load within an approved build-up, or project-designed screed or concrete. The chosen system must distribute loads without crushing the 3mm studs and must not introduce fixings through the membrane. Check point loads, partitions, underfloor heating, insulation, finished floor levels and required expansion gaps before installation. Individual boards, screeds, adhesives and finishes must also meet their manufacturers’ moisture, curing, loading and installation requirements.

Q) What are the main technical specifications of Wykamol CM3?

A) Wykamol CM3 is a clear HDPE membrane weighing 0.5kg/m², with a 0.6mm sheet thickness, 3mm stud height, 20mm stud centres and an air-gap volume of 2.19litres/m². It passes watertightness testing at 60kPa for 24hours and has water-vapour resistance above 3,020MNs/g. Tensile strength is 416N in the machine direction and 488N in the cross direction. Static-loading resistance exceeds 20kg, while compressive strength is 250kN/m². Its stated working-temperature range is minus 50°C to plus 80°C, with a softening temperature of 126°C. These are membrane properties rather than performance guarantees for the complete installed system.

Q) Which standards and certifications apply to Wykamol CM3?

A) Wykamol CM3 is covered by BBA Agrément Certificate 18/5595 within its certified scope. It is declared as a Type V damp-proof sheet under BS EN 13967:2012+A1:2017 and achieves reaction-to-fire Class E to EN 13501-1:2007+A1:2009. Watertightness passes at 60kPa for 24hours to EN 1928. Below-ground Type C systems incorporating CM3 should be risk-assessed, designed and maintained in accordance with BS 8102:2022. Certification applies to the membrane and defined uses, not automatically to every component or the completed basement. Project compliance therefore depends on the retaining structure, drainage, discharge, detailing, protection, workmanship, fire strategy, commissioning and ongoing maintenance as a coordinated whole.

Q) How long should Wykamol CM3 last, and what maintenance is required?

A) Under normal service conditions, Wykamol CM3 can remain an effective barrier to salts, liquid water and water vapour for the life of the structure in which it is incorporated when correctly specified, installed and protected. The concealed membrane does not normally require routine surface maintenance, but the Type C drainage system does. Keep Waterguard, Floor Drain, jetting eyes, gravity outlets, sumps, pumps, alarms, backup power and discharge pipework accessible and service them at the specified intervals. Flush channels, remove lime or silt, test pumps and float switches, clean sump chambers and operate alarms. Record all servicing, and investigate unusual pump activity, odours, dampness or changing water levels promptly rather than waiting for visible damage.

Q) What are the main limitations of the Wykamol CM3 Waterproof Membrane Kit?

A) The kit is not a complete waterproofing, drainage, discharge, protection or finishing system, and CM3 does not resist hydrostatic pressure as a standalone barrier. Nominal roll areas do not allow for waste, while the supplied plugs and tape may be insufficient for complex joints, close fixing centres, vaults or repairs. The shallow cavity must remain free from lime, silt, mortar, drilling dust and crushed studs. CM3 cannot receive direct plaster or render, must be protected from later punctures and should not conceal structural defects, active decay or unknown contamination. For Grade 3 protection where retained ground exceeds 600mm, BBA Certificate 18/5595 requires CM3 to be combined with Type A or Type B protection.

Q) What practical tips help achieve a reliable Wykamol CM3 installation?

A) Complete a detailed survey and measured take-off before ordering, including roll orientation, butt joints, corners, drainage connections, fixings, penetrations, repair allowance and waste. Store the membrane and butyl products clean, dry and at a workable temperature. Use a level reference on walls, drill through stud centres, remove dust from holes and seat plugs without crushing the sheet. Clean and dry every taped area, apply firm roller pressure and use only controlled warmth where required. Protect completed CM3 immediately from foot traffic, sharp tools and follow-on trades. Introduce controlled clean water behind the membrane to test flow before concealment, photograph critical details and provide the owner with drawings, test records and a maintenance schedule.

Technical Data Sheet

Declaration of Performance (DoP)

BBA Certificate