Newton CDM 508R RADON Membrane - 8mm Studded Waterproof Radon Barrier Membrane

Health & Safety And Installer Competency

Newton 508R is a professional-grade 8mm studded cavity drain membrane and radon gas barrier intended for use as part of the Newton CDM Type C waterproofing system. It should be installed only by suitably experienced contractors who understand structural waterproofing, cavity drain membrane installation, drainage design, pump systems, gas barrier detailing and below ground waterproofing requirements. Newton states that the CDM System should be installed by trained Newton Specialist Contractors, which is also stated as a requirement of the BBA Certificate.

Before installation, the relevant Technical Data Sheet and Newton CDM Installation Manual should be read in full. Suitable PPE should be worn throughout the work, including gloves, safety glasses and appropriate protective clothing. Where drilling, cutting, trimming or preparing masonry is involved, dust control, respiratory protection, hearing protection and safe electrical working practices should be considered. Staging or scaffold should be used for safe working at height, particularly when applying Newton 508R to high walls, vaulted soffits or arch details. The manual identifies PPE, gloves and safety glasses as minimum wall installation requirements, alongside suitable drilling, cutting and measuring equipment.

System Design Principles

Newton 508R must not be treated as a standalone waterproofing product. It has no capability to withstand water pressure by itself and must be used as part of a correctly designed Type C cavity drain waterproofing system that safely collects and removes water from the building. The Newton CDM System works by creating depressurisation spaces using the studded membrane and drainage channels, then directing water to a safe discharge point, such as a sump and pump system or reliable gravity drainage.

For below ground waterproofing work, the overall design should be considered in accordance with BS8102:2022. The manual notes that adequate drainage and water removal must be included within the design to remove water from behind the system, and that the Newton CDM System will not hold back water pressure. The structure itself must be capable of controlling the rate of water ingress so that the cavity drain system is not overwhelmed. This is especially important in basements, cellars, retaining walls, earth-retained structures and projects where high groundwater, surface flooding, burst mains or future climate-related water loads may be possible.

Suitable Substrates

Newton 508R is suitable for use on walls, floors and vaulted soffits within the Newton CDM system. For wall applications, suitable substrates include concrete, brick, concrete block and ICF, although ICF requires special longer fixing plugs. For soffit applications, the suitable backgrounds are concrete to a fall and arched or vaulted brick. For floor applications, Newton 508R is suitable over a concrete raft or slab, and it can also be used above Newton Fibran XPS 500-C closed cell extruded polystyrene insulation where the floor design includes the approved insulation spacer build-up.

The membrane is suitable for waterproofing earth-retained walls, vaulted soffits and floors. It is also independently tested as a barrier to radon ground gases and hydrocarbons, and is the selected membrane for Newton PAC-500 combined ground gas and waterproofing system applications. When radon or hydrocarbon barrier performance is required, all laps, joints, penetrations, fixings, edges, condensation gaps and interfaces must be treated as part of a complete gas-resisting system, not merely as a standard drainage membrane installation.

Preparation Of Walls, Floors And Soffits

All timber and organic material should be removed before the Newton 508R membrane is installed. This includes skirting boards, timber plates, old wallpaper and any other material that may support fungal or bacterial growth behind the membrane. If there is evidence of rot, this should be dealt with by a specialist before installation. Any mould should be cleaned away and the area sterilised with a suitable fungicidal wash. Uneven or deteriorated wall areas should be made good so the membrane can be fixed securely and sit neatly against the substrate.

For floor applications, the floor must be cleared of oil, loose material and sharp protrusions. Holes, severe depressions and irregular areas should be filled or levelled before installation. The performance of the drainage system is directly affected by the gradient, flatness and regularity of the slab or raft, so the existing floor should be checked carefully before the membrane is installed. Newton recommends surface regularity of SR1 or better, which is 3mm on a slip gauge, and the manual advises that testing may be carried out by water flood testing or laser level checks.

When installing Newton 508R to floors, the slab should be checked against the drainage datum point, which is the slab height where the drainage channel sits adjacent to the sump chamber. Deviation from this datum must not be more than -5mm at any point between the datum and the furthest point of the waterproofing system. Deviation may be up to +15mm only where it occurs at the furthest point from the datum, not at an intermediate high point that could trap water. Any irregularities should be corrected by planing, grinding or using a suitable levelling compound.

New concrete should be treated with Newton 106 Lime Inhibitor or Wykamol Anti Lime Sealer to reduce the risk of free lime being drawn out of the curing concrete by incoming water. This is important because lime scale deposits can block drainage paths, drainage channels and membrane voids over time. Where drainage channels are used, water must be able to flow uninterrupted to the discharge point, as standing water can lead to silt or lime scale blockages.

Anti-lime sealer being applied to prepared concrete before installation of Newton 508R Waterproof Membrane.

Tools And Ancillary Products Required

For wall installation, the minimum required tools include a good quality 110V SDS hammer drill, mallet or club hammer, sharp knife with spare blades, tape measure, long spirit level, suitable SDS drill bits, clean rags, staging or scaffold for work at height, gloves and safety glasses. A 10mm SDS Drill Bit is required where Newton CDM MultiPlug is used, while the CDM NuSeal Plug requires an 11mm drilled hole. Recommended additional tools include extra lighting, a 110V hot air gun and a rotating laser level.

Newton 508R installation commonly requires Newton CDM Joint Tape, Newton CDM Rope, Newton CDM OverTape, CDM MultiPlug, CDM NuSeal Plug and suitable drainage components such as CDM BaseDrain or CDM FloorDrain. CDM Joint Tape is a butyl tape used for jointing membranes along the flange. CDM Rope is a 10mm butyl rope used where a flange seal is not possible. CDM OverTape is used for connecting floor membranes to CDM BaseDrain upstands, connecting floor membranes to wall membranes, sealing abutting joints, carrying out repairs and forming reveal details.

Drainage Requirements

Newton 508R must be installed with a drainage strategy that removes water from below and behind the membrane. CDM BaseDrain is positioned at the wall-to-floor junction to collect water from behind the wall membrane and from the vulnerable wall-to-floor junction. It can interface with sump chambers, gullies and waste pipes, and it can be made maintainable through Newton inspection ports. Where existing floors do not allow sufficient headroom for CDM BaseDrain within a spacer of Newton Fibran XPS 500-C insulation, CDM BaseBoard may be considered as the drainage method.

The drainage route should be planned before the membrane is fitted. Water must be directed to a safe discharge point, normally a sump chamber with a correctly specified pumping system or a safe gravity drainage outlet where backflow cannot occur. Water must not be allowed to collect behind or beneath the membrane, as stagnant water can block the system with silt or lime scale and may pressurise areas that were intended to remain depressurised.

Newton CDM Basedrain positioned at the wall-to-floor junction to collect water from behind the Newton CDM 508R Waterproof Membrane, with Newton CDM Overtape securing the channel to the Newton Condensation Strip and Newton CDM Fibran XPS 500-C Insulation beneath (via Newton CDM 508R Waterproof Membrane as a floor membrane). 

Wall Installation

Newton 508R may be fixed to walls either vertically or horizontally. Horizontal fixing generally requires fewer cuts and fewer joints, but the roll is heavy at the start of the installation. Vertical fixing creates lighter sheets that are easier to handle, but it requires more jointing because each sheet must be taped back together. The choice should be based on wall height, roll width, available access, number of corners, installer experience and the need to maintain clean, straight, sealed joints.

Place the membrane in position as level as possible. Drill through the centre of a stud near the top and edge of the membrane to a depth greater than the fixing. The fixing is then hammered into the pre-drilled hole until the plug sits flush in the stud. For wall applications, the rubber washer fitted to the CDM MultiPlug re-seals the hole. The sheet should then be levelled using a long spirit level or rotating laser level, with another fixing placed approximately 2m along the top edge so the membrane hangs level to the wall.

For horizontal wall fixing, continue fixing at approximately 2m intervals along the top line until the wall area is covered or the roll ends. The level should be checked regularly, as an out-of-level membrane can kink, look untidy and fall away incorrectly when taken around corners. For vertical wall fixing, each following sheet should be hung in the same way using initial top fixings. The next sheet should overlap by at least the width of the flange, or the first stud of the new sheet may be interlocked with the last stud of the previous sheet to help keep the installation straight and level.

Vertical joints are sealed with CDM Joint Tape. It is generally easier to apply the tape to the inner surface of the flange on the next sheet before the sheet is fully sealed into place. The flange and the face of the previous sheet must be cleaned with a clean rag before sealing. Once the sheet is fixed level with the correct overlap, remove the backing paper from the tape while applying pressure to the flange. After the backing paper has been removed, apply further pressure with the palm of the hand to seal the full joint. A hot air gun should be used to assist sealing, especially in cold or damp conditions.

Typical wall and floor junction detail showing Newton 508R Waterproof Membrane installed as part of a cavity drain waterproofing system, with associated drainage, fixing, insulation and screed components.

Wall Fixing Centres And Internal Finishes

The required fixing centres depend on the intended internal wall finish. Where timber battens are used, fixings should be at 600mm centres vertically and 400mm centres horizontally. Where a fixed metal track system such as Gypliner is used, fixings should be at 800mm centres vertically and 600mm centres horizontally. Brick or block walls restrained to the retaining wall using ties require fixing centres that provide the correct number and spacing of restraints. Free-standing timber frames, metal frames and free-standing block walls do not require specific fixing centres, but enough fixings should be used to hold the membrane neatly and reasonably tight to the wall, particularly at corners and reveals.

If battens are used, they should be pre-treated and at least 25mm x 38mm, although 25mm x 50mm can provide better support at plasterboard edges. Battens can be fixed into the CDM Fixing Plug without piercing the membrane by using size 10, 5mm self-tapping screws. The plug accepts up to 30mm of screw, so the screw length must be selected to suit the batten thickness. Over-tightening or using screws that are too long can loosen the plug or damage the membrane. Plasterboard should be fixed to the battens using suitable plasterboard fixings, making sure the fixing length does not exceed the batten depth and puncture the membrane.

Because Newton 508R is NOT a meshed membrane, it should not be plastered or rendered directly in the way that a meshed membrane would be. Wall protection and finishing should normally be formed using a floor-supported dry-lining frame and plasterboard, or timber battens fixed into Newton MultiPlugs to support plasterboard or timber sheeting. The chosen finish must protect the membrane from physical damage, UV exposure and fire exposure.

Newton MultiPlugs fixing Newton 508R to the wall, with fixing centres set to suit the internal finish, typically 600mm vertically and 400mm horizontally for timber battens.

Floor Installation

Before installing Newton 508R as a floor membrane, prepare and test the floor as described above. The floor should be clean, level and free from sharp projections, loose material and contaminants. Both edges of the membrane must be cleaned before a seal is made. The membrane is unrolled from one side of the room with the studs down and cut to fit the room in the same manner as a carpet.

The next width of membrane is rolled out so that the flanged edge overlaps onto the edge of the previous roll. CDM Joint Tape is applied to the high flat area between the first two studs at the edge of the previous roll, with the backing paper left in place until alignment has been checked. The flange of the next sheet should cover the backing paper. Starting from the end of the joint, remove the backing paper and press down firmly to seal the two sections together. Continue this process until the floor area is fully covered.

The Newton 508R floor membrane should be sealed to the upstand of the CDM BaseDrain channel, or to the CDM Condensation Strip if fitted, using CDM OverTape. A heat gun should be used to dry the membrane surface and improve tape bonding where necessary. Where the floor membrane has to connect to horizontal DPCs such as Damp Proof Course (DPC) through internal or external walls, seal these joints with CDM Joint Tape, ensuring both surfaces are clean and dry before sealing.

Services passing through the floor should be avoided wherever possible because they create weaknesses that may allow unnecessary water ingress. Where a service penetration is unavoidable, cut and trim the membrane around the service, then fill and seal the gap using the appropriate Newton adhesive or sealing products. Where required, a membrane patch or Damp Proof Course (DPC) patch can be laid over the area and sealed to the service with CDM Rope, then sealed around the perimeter with CDM Joint Tape. Newton Pipe Collar or Newton Pipe Sleeve may also be used where suitable.

Once the floor membrane has been installed and checked, the specified floor finish can be laid directly over it, but the membrane must not be punctured by fixings through the floor. If a timber floor finish is being installed, an expansion gap must be left around the wall edge in accordance with the flooring supplier’s requirements. New concrete slabs or screeds can receive the membrane as soon as they are walkable, allowing fast-track floor finishing without waiting for normal relative humidity levels, because construction moisture is controlled within the air gap.

Vaulted Soffit Installation

Newton 508R can be used for vaults and vaulted soffits. When applying it to vaulted construction, laps and joints must be detailed so water drains correctly and does not sit on joints. The rubber sealing washer supplied with CDM MultiPlug must not be used on vaulted ceilings or soffits. Instead, a seal must be formed using a ring of CDM Rope around the chosen fixing with CDM NuSeal Plug.

For vaulted cellars, measure the depth of the vault from the front wall to the back wall and allow a 200mm downturn at each end. Unroll the sheet and cut it to size. Mark the approximate centre of the arched ceiling, then measure down the arch by 1.2m and mark again. Strike a horizontal line along the wall from back to front to provide a guide line for the sheet edge. This helps keep the sheets square and symmetrical as they are fixed along the length of the vault.

Offer the first section of Newton 508R to the ceiling, allowing a 200mm lap to the back wall. Using the guide line to keep the sheet square, drill and fix the sheet along the apex of the arch, following the same line of studs. Fix through the centre of the membrane studs at approximately 600mm centres, keeping the fixings aligned because they also provide the fixing points for battens. The next sheet is cut to size with 200mm laps at each end. Before positioning it, apply CDM Joint Tape to the edge of the previous sheet, either on the flanged edge or between the last two rows of studs on the non-flanged edge. Offer up the new sheet so the flange overlaps the sealing tape, then remove the protective paper from the middle outwards and form the seal. Continue the process until the arch and the vertical walls below the springer are covered.

At the end walls of a vaulted structure, a flat membrane end piece is fitted to the end wall. The 200mm lap from the soffit membrane is cut in fan sections to follow the curve of the arch and sit neatly against the wall. Each cut should be filled with a small piece of CDM Rope or CDM Joint Tape. The cuts should be kept to a minimum and should not be taken all the way up to the ceiling. The end wall membrane is cut to size, fixed in front of the fanned ceiling membrane and trimmed neatly into the curve. The membrane is then pulled back at the sides and around the arch so the studs on the reverse can be accessed, then CDM Rope is used to form the stud-to-stud joint, following the contour of the arch.

Flat Soffit Restrictions

Flat soffits require particular care. Newton 508R should not be applied to flat soffits unless the soffit is at least 400mm narrower than the membrane being used, and only very experienced contractors should attempt this type of installation.

Where flat soffits are considered, the soffit must have a fall in accordance with the drainage requirements, and the membrane must not sag in a way that allows ponding. Installations to flat soffits should follow the principles of inverted cavity drain systems in BS8102:2022.

Door Reveals, Corners And Junction Details

At door openings within vaulted or membrane-lined areas, a section of membrane should be fitted around the door head and lapped down the sides by approximately 100mm. The wall membrane can then be wrapped around the sides while maintaining the correct drainage detail and forming an overlap. Any small gap created at the angle of the door opening should be sealed using CDM OverTape.

Corners, reveals, wall-to-floor junctions and penetrations are critical points in a Newton 508R installation. The membrane should be kept neat, tight and correctly drained, with the sealing detail chosen according to whether the joint is a flange joint, stud-to-stud joint, floor-to-wall junction, pipe penetration or repair. Surfaces being sealed must be clean and dry before tapes or ropes are applied. A hot air gun can be used to warm the membrane and tape where this improves adhesion, especially in cold or damp conditions.

Protrusions Through Newton 508R

Where pipes, steelwork or other protrusions pass through Newton 508R, the membrane must be cut neatly and sealed carefully. The technical drawing in the manual shows protrusions through Newton wall or floor membrane being sealed with CDM Rope and CDM OverTape. It also notes that the protrusion may need priming with a suitable primer such as Newton 109-LM to ensure adhesion of the sealing product to the protrusion.

Penetrations should be avoided wherever possible, especially through floor slabs or rafts, because they create weaknesses where water ingress can occur. Where they cannot be avoided, the seal must be detailed as part of the waterproofing and, where applicable, radon or hydrocarbon barrier specification. The completed detail should be inspected before finishes are installed, because later access may require removal of screeds, linings or finishes.

Radon Gas And Hydrocarbon Barrier Detailing

Newton 508R is independently tested as a barrier to radon gas and hydrocarbons, but barrier performance depends on the complete installed system. The membrane itself, the joints and the detailing around penetrations must be continuous and properly sealed. The Technical Data Sheet gives radon gas resistance values for both the membrane and joints, and confirms that resistance to liquid hydrocarbons has passed the relevant testing.

Where the Newton CDM system is also being used as a gas barrier, the condensation gap may need to be sealed. The manual states that sealing the condensation gap is necessary in certain situations, including where the Newton waterproofing system is used as a gas barrier. If the condensation gap is sealed, the ventilation system must always work as designed.

Protection Of Newton 508R After Installation

Newton 508R must always be protected by suitable surface finishes. On walls and vaulted soffits, protection methods include a floor-supported dry-lining frame with plasterboard, or timber battens fixed into Newton MultiPlugs to support plasterboard or timber sheeting. On floors, suitable protection methods include floating screeds, tongue and groove chipboard, timber floors supported by a fixed lattice of timber supports, insulation with screed or tongue and groove chipboard above, or underfloor heating trays with screed above.

Where screeds are placed above non-bonded HDPE membranes such as Newton 508R, they are classed as floating screeds under BS8204 and BS13318. Sand and cement floating screeds should be at least 65mm thick, while proprietary liquid screeds typically require 35-40mm, subject to checking the load capability with the screed supplier. Newton 508R has a long-term compressive loading of 7kPa as membrane only, and 800kPa where the load is transferred through a C16 floating screed. Filling the studs with sand may appear to increase load distribution, but Newton notes that this has not been tested.

Fire Protection

Newton 508R is classified as Euroclass F for reaction to fire, the same classification noted for plastic-based insulation. It must therefore be protected from fire by suitable surface finishes, just as insulation would be.

Where a project requires a higher fire-rated membrane, Newton states that fire-resistant membranes tested and classified to B-s2.d0 can be supplied, but this is a different specification consideration and should not be assumed for Newton 508R itself.

Ventilation And Humidity Control

Newton 508R provides vapour control when used with appropriate humidity control systems and can contribute to environments capable of achieving all levels within a Grade 3 environment under BS8102:2022. However, the internal environment must still be designed correctly. Where the membrane and drainage system are installed behind internal linings, condensation and humidity must be considered, especially in habitable basement conversions, storage rooms and occupied below ground areas.

If the condensation gap is left open, it can assist the intended cavity drainage arrangement. If the condensation gap is sealed for gas barrier purposes, ventilation and humidity control become more important because trapped moisture must still be managed safely. Where gas protection, waterproofing and internal environmental control are all required, the specification should be designed as a complete system rather than as a simple membrane installation.

Inspection Before Finishes

Before any screed, dry lining, boarding or other finishes are installed, the entire Newton 508R installation should be checked carefully. All joints, laps, tapes, penetrations, fixings, corners and floor-to-wall interfaces should be inspected.

Any damaged areas must be repaired before finishes are applied, and all joints and seals should be checked to confirm they are adequate. This is essential because access becomes much more difficult once floors, battens, plasterboard, screeds or other finishes are in place.

Repairs To Newton 508R

If the wrong stud is drilled during wall installation, the error can be repaired by cleaning out the stud with a clean cloth, plugging it with CDM Rope and covering it with a small patch of CDM OverTape. The same repair method can be used where a fixing has not been achieved due to drilling into an unsound joint or substrate, and where the CDM Fixing Plug expansion pin has not corrected the problem. A new fixing should then be formed in another stud.

Clean cuts, accidental piercings, rips and tears in the membrane should be sealed with CDM OverTape. For a clean cut, the tape should bridge both edges and extend at least 25mm beyond the furthest points of the cut. For a hole, CDM OverTape can be used provided the hole can be bridged in one piece with at least a 25mm margin around the damaged area. Larger damage can be repaired with a patch of membrane that extends beyond the hole, sealed with CDM Joint Tape if the patch sits neatly into the studs, or sealed around the perimeter with CDM OverTape if the studs do not interlock.

For floors and vaulted ceilings, damage can be repaired using the same general methods, but CDM OverTape must always be used to bridge or seal the damage. All surfaces must be clean and dry before the repair is made. In some cases, warming the membrane and CDM OverTape with a hot air gun can help remove surface moisture and improve the seal. Where multiple areas of damage are present in one membrane section, it may be better to cut out and replace that section with a larger piece of membrane.

Maintenance And Future Alterations

The Newton CDM system requires very little maintenance, but the drainage and pumping elements must remain serviceable. Mechanical pumps and drainage systems should be inspected at least once a year by a competent person. Maintenance should include cleaning and descaling the pumping system as required, checking the free movement of the pump impeller, checking pump seals, carrying out an impeller test, inspecting discharge pipes for damage and leaks, removing debris from the sump base, checking electrical connections and fuses, and flushing through the CDM BaseDrain and CDM FloorDrain drainage system.

Sump pumps rely on electricity, so a constant power supply is important for maximum drainage capacity. Battery backup systems may be required where pump continuity is critical. The membrane itself should not be pierced after installation. If future works are planned in the basement or waterproofed area, including shelving, cupboards, dry lining alterations or other fixings, advice should be obtained from the specialist installing contractor before work begins. Even minor penetrations can compromise the waterproofing and gas barrier performance if they are not detailed correctly.

Key Limitations

Newton 508R must not be used as an isolated waterproof barrier or a product expected to resist hydrostatic pressure on its own. It must be installed as part of a Type C cavity drain waterproofing system with designed drainage and water removal. The membrane should not be installed where water can build up behind or below it without a safe path to discharge.

Do not install Newton 508R to flat soffits unless the soffit is at least 400mm narrower than the membrane being used, and only very experienced contractors should carry out that work. Do not allow the membrane to sag on soffits, because ponding can occur. Do not puncture the floor membrane with fixings through the floor finish. Do not use Newton 508R without protecting it from fire, UV exposure, physical damage and wear. Do not assume gas barrier performance unless all joints, laps, gaps, penetrations and interfaces are detailed as part of a complete gas barrier system.

Other Technical Information

Newton 508R is supplied with a 30-year product warranty and has a life expectancy of at least 100years, but Newton notes that this is not the same as a waterproofing guarantee. The waterproofing guarantee is provided by the specialist waterproofing contractor. When specified, installed and protected in accordance with the Data Sheet and Installation Manual, fully isolated from UV light, physical damage and wear, and installed only to the confirmed substrates, Newton 508R has a service life equal to the design life of the structure.

The membrane has a temporary compressive strength of 280kPa, a permanent compressive strength of 7kPa, and a permanent load transfer value of 800kPa through a C16 screed. It has a water vapour resistance Sd value greater than 604m, a μ value greater than 1208000μ and water vapour diffusion resistance greater than 3020MNs/g. It also has excellent chemical resistance and oxidation resistance, and has tested radon gas resistance values for both membrane and joints. These performance values support its use in demanding basement waterproofing, radon gas barrier, hydrocarbon barrier and below ground Type C waterproofing specifications, provided the complete system is correctly designed and installed.

Q) What is Newton 508R Waterproof Membrane?

A) Newton 508R Waterproof Membrane is a premium 8mm studded cavity drain membrane designed for use within the Newton CDM Type C waterproofing system. It is used internally on walls, floors and vaulted soffits to manage water ingress rather than simply trying to block it at the surface. The studded profile creates a drainage cavity behind the membrane, allowing water to be directed safely towards channels, sumps or gravity drainage. Newton 508R is heavier and stronger than standard 8mm membranes, making it suitable for demanding below ground work. It is also independently certified as a radon gas barrier and hydrocarbon barrier, giving it wider use in contaminated or gas-affected sites.

Q) How does Newton 508R Waterproof Membrane work?

A) Newton 508R Waterproof Membrane works by creating a controlled cavity between the structure and the internal finish. Water entering through an earth-retained wall, floor or vaulted soffit is allowed to move behind or beneath the membrane and is then directed to a designed drainage route. This is the principle of Type C waterproofing under BS8102:2022. Instead of relying on a bonded coating to resist all water pressure, Newton 508R manages water safely within the system. For this reason, it must be used with appropriate drainage, such as Newton CDM BaseDrain or Newton CDM FloorDrain, and where needed a sump and pump system. The membrane itself does not hold back hydrostatic pressure on its own.

Q) What is Newton 508R used for?

A) Newton 508R is used for basement waterproofing, cellar conversions, below ground refurbishment, floor waterproofing, earth-retained walls, vaulted soffits and ground gas protection. It is particularly suited to Type C cavity drain waterproofing systems where water needs to be collected and removed in a controlled way. The membrane can also be specified where radon gas resistance or hydrocarbon barrier performance is needed, provided the complete system is correctly jointed and sealed. Typical projects include domestic basements, commercial below ground spaces, retaining structures, arches, tunnels, contaminated ground sites and waterproof floor build-ups. Its combination of strength, compressive stability and chemical resistance makes it a robust option for demanding internal waterproofing specifications.

Q) Is Newton 508R suitable for basement waterproofing?

A) Yes, Newton 508R is highly suitable for basement waterproofing when it is installed as part of a correctly designed Newton CDM Type C waterproofing system. Basements and cellars are commonly affected by lateral moisture, water pressure, salts and damp substrates, so a maintainable cavity drain system is often more practical than relying only on bonded tanking. Newton 508R creates a drainage space that manages water behind internal finishes and directs it towards a suitable drainage outlet. When designed with the correct drainage channel, sump, pump and humidity control measures, it can contribute to internal environments capable of meeting Grade 3 requirements under BS8102:2022. Professional design and installation are essential for reliable performance.

Q) Can Newton 508R Waterproof Membrane be used on walls and floors?

A) Yes, Newton 508R Waterproof Membrane can be used on walls and floors within the Newton CDM system. On earth-retained walls, it is mechanically fixed to the substrate and directs water downwards into the drainage channel. On floors, it is laid with the studs down over a prepared slab or raft and jointed using Newton CDM Joint Tape. The floor membrane is then connected to Newton CDM BaseDrain or other appropriate drainage details using Newton CDM OverTape. Floor preparation is especially important because the slab must be level, clean and free from sharp projections. Where floor finishes are installed above Newton 508R, fixings must not puncture the membrane.

Q) Is Newton 508R suitable for vaulted soffits and arched structures?

A) Yes, Newton 508R is suitable for vaulted soffits, arches and similar below ground structures, but the detailing must be carried out carefully by experienced installers. Vaulted installations need the laps and joints arranged so water drains correctly and does not sit on the joint lines. The normal rubber washer arrangement used with Newton CDM MultiPlug is not used on vaulted soffits. Instead, a seal is formed using Newton CDM Rope around the fixing with Newton CDM NuSeal Plug. The membrane is fixed along the curve of the arch, with joints sealed using Newton CDM Joint Tape and reinforced where needed.

Q) Can Newton 508R be used on flat soffits?

A) Newton 508R should only be used on flat soffits in very limited circumstances and only by highly experienced contractors. The soffit must be at least 400mm narrower than the membrane being used, and it must have a suitable fall so water can drain correctly. The membrane must not sag, as this can allow ponding and create a failure risk within an inverted cavity drain arrangement. Flat soffit installations should follow the principles of inverted cavity drain systems in BS8102:2022. In practice, this is a specialist application requiring careful assessment of the structure, drainage route, fixing method and long-term maintainability. It should never be treated as a routine installation detail.

Q) Is Newton 508R a radon gas barrier?

A) Yes, Newton 508R is independently tested as a radon gas barrier, with stated radon gas resistance values for both the membrane and joints. This makes it suitable for projects where radon protection and waterproofing need to be addressed together. However, radon barrier performance depends on the complete installed system, not just the membrane sheet. All laps, joints, penetrations, fixings, condensation gaps, edges and interfaces must be properly sealed and detailed. If the Newton CDM system is being used as a gas barrier, the condensation gap may need to be sealed, and ventilation must then work as designed. For radon-affected sites, installation should follow a full gas-resisting specification.

Q) Is Newton 508R suitable for hydrocarbon contaminated sites?

A) Yes, Newton 508R has been independently tested for resistance to liquid hydrocarbons to EN16140:2011, making it suitable for certain contaminated ground applications where hydrocarbon barrier performance is required. It is also the selected membrane for use within the patented Newton PAC-500 combined ground gas and waterproofing system. This makes Newton 508R particularly relevant on sites where waterproofing, radon protection and hydrocarbon resistance may need to work together. As with radon protection, hydrocarbon barrier performance depends on the full system being correctly designed and sealed. Joints, service penetrations, edges and interfaces must be treated as part of the barrier system, not as ordinary membrane overlaps.

Q) What makes Newton 508R stronger than a standard 8mm membrane?

A) Newton 508R is heavier and stronger than standard 8mm cavity drain membranes, giving it improved robustness for demanding below ground applications. Its physical strength is particularly valuable on floors, where long-term loading may come from screeds, insulation, internal partitions, finishes and normal use of the building. Third-party testing to ISO25619-1 shows just 2% compression over 50 years, which supports confidence in its long-term dimensional stability. It also has a permanent load transfer value of 800kPa through a C16 screed, demonstrating the importance of the correct floor build-up. This makes Newton 508R a strong choice where a more robust cavity drain membrane is needed for loaded applications.

Q) What certifications does Newton 508R Waterproof Membrane have?

A) Newton 508R Waterproof Membrane is supported by BBA Certification Number 94/3010, which provides independent assessment of its suitability and performance under defined use conditions. It is used as part of a Type C waterproofing system relevant to BS8102:2022 and has third-party testing for long-term compressive load performance to ISO25619-1. It also has water vapour resistance testing to BSEN1931, thermal conductivity testing to EN12667, chemical resistance testing to EN14030 and oxidation resistance testing to ENISO13438. Radon gas resistance testing confirms its suitability as a radon barrier when correctly jointed, and EN16140:2011 testing supports its use as a liquid hydrocarbon barrier in appropriate contaminated ground specifications.

Q) Can Newton 508R help achieve a Grade 3 basement environment?

A) Newton 508R can contribute to an environment capable of achieving all levels within Grade 3 under BS8102:2022, but only when used as part of a correctly designed waterproofing system. A Grade 3 environment is typically required where the internal space must be suitable for habitable use, storage of sensitive items or high-quality commercial use. The membrane helps manage water and vapour, but drainage, sump and pump design, ventilation, humidity control and internal finishes all matter. Newton 508R should not be viewed as a standalone solution. The full Newton CDM system must be specified to suit the structure, water risk and intended use of the space.

Q) What substrates can Newton 508R be installed onto?

A) Newton 508R can be installed onto suitable walls, floors and vaulted soffits within the Newton CDM system. For wall applications, typical substrates include concrete, brick, concrete block and ICF, although ICF requires special longer fixing plugs. For soffits, suitable backgrounds include concrete formed to a fall and arched or vaulted brick. For floor applications, Newton 508R is used over a concrete slab or raft, and it can also be used above Newton Fibran XPS 500-C closed cell extruded polystyrene insulation where the approved floor build-up is used. The substrate must be stable, suitably prepared and capable of supporting the membrane and drainage system without compromising performance.

Q) How should walls be prepared before installing Newton 508R?

A) Before installing Newton 508R to walls, all timber and organic material should be removed, including skirting boards, timber plates, wallpaper and anything that could support fungal or bacterial growth behind the membrane. Any rot should be assessed and treated by a specialist before installation begins. Mould should be cleaned away and the area sterilised with a suitable fungicidal wash. Loose, uneven or deteriorated wall areas should be made good so the membrane can be fixed securely and sit neatly against the substrate. The aim is not to create a perfectly smooth tanking surface, but the wall must be sound enough to accept fixings and support a clean, reliable cavity drain installation.

Q) How should floors be prepared before Newton 508R is installed?

A) Floors should be clean, level and free from oil, loose material, sharp projections and severe depressions before Newton 508R is installed. Holes and irregular areas should be filled or levelled so the membrane sits properly and drainage is not compromised. Newton recommends surface regularity of SR1 or better, which is 3mm on a slip gauge. The floor should also be checked against the drainage datum point, especially where water must flow towards Newton CDM BaseDrain, Newton CDM FloorDrain or a sump chamber. New concrete should be treated with Newton 106 Lime Inhibitor or Wykamol Anti Lime Sealer to reduce the risk of free lime deposits blocking drainage paths as water passes through the system.

Q) What drainage products are normally used with Newton 508R?

A) Newton 508R is normally used with a planned drainage system that may include Newton CDM BaseDrain, Newton CDM FloorDrain, inspection ports, sump chambers and pump systems. Newton CDM BaseDrain is commonly positioned at the wall-to-floor junction to collect water from behind wall membranes and from vulnerable wall-floor junctions. Newton CDM FloorDrain may be used where floor drainage is required. The key point is that water must be directed to a safe discharge point and must not be allowed to stagnate behind or beneath the membrane. If water sits within the system, silt and lime scale can accumulate and restrict drainage. Correct drainage design is therefore central to Newton 508R performance.

Q) How is Newton 508R fixed to walls?

A) Newton 508R can be fixed to walls either vertically or horizontally, depending on access, wall height, corner details and installer preference. Horizontal fixing often reduces cuts and joints, while vertical fixing creates lighter sheets but requires more jointing. The membrane is placed level against the wall, then drilled through the centre of a stud using the correct drill size for the chosen fixing. Newton CDM MultiPlug or Newton CDM NuSeal Plug is then installed so the fixing sits correctly in the stud. For standard wall applications, the rubber washer on the fixing helps reseal the drilled hole. Fixing centres depend on the intended internal finish, such as battens, metal framing or free-standing linings.

Q) What tapes and ancillary products are used with Newton 508R?

A) Newton 508R installation commonly uses Newton CDM Joint Tape, Newton CDM Rope, Newton CDM OverTape, Newton CDM MultiPlug and Newton CDM NuSeal Plug. Newton CDM Joint Tape is a butyl tape used for jointing membranes along the flange. Newton CDM Rope is used where a flange seal is not possible or where stud-to-stud detailing is needed. Newton CDM OverTape is used for floor-to-wall connections, floor membrane to Newton CDM BaseDrain upstands, repairs, reveal details and abutting joints. These products are not optional finishing accessories. They form part of the waterproofing and, where relevant, gas barrier detailing, so surfaces must be clean and dry before tapes and ropes are applied.

Q) Can Newton 508R be plastered or rendered directly?

A) No, Newton 508R is not a meshed membrane and should not be plastered or rendered directly. It should be protected with suitable internal finishes, such as a floor-supported dry-lining frame with plasterboard, or timber battens fixed into Newton CDM MultiPlugs to support plasterboard or timber sheeting. The finish must protect the membrane from physical damage, UV exposure and fire exposure. If battens are used, they should be pre-treated and correctly fixed without piercing the membrane outside the intended fixing points. Plasterboard fixings must be chosen carefully so they do not pass through the batten and puncture the membrane. Correct finishing is essential to protect the system.

Q) What floor finishes can be installed over Newton 508R?

A) Newton 508R can be protected with suitable floor finishes including floating screeds, tongue and groove chipboard, timber flooring supported by a fixed lattice of timber supports, insulation with screed or chipboard above, or underfloor heating trays with screed above. Where screeds are placed above non-bonded HDPE membranes such as Newton 508R, they are classed as floating screeds under BS8204 and BS13318. Sand and cement floating screeds should generally be at least 65mm thick, while proprietary liquid screeds may require 35mm to 40mm depending on supplier guidance. Floor finishes must not puncture the membrane. If fixings are needed, the detail should be checked with the specialist installer before work proceeds.

Q) How are pipes and penetrations sealed through Newton 508R?

A) Pipes and penetrations through Newton 508R should be avoided wherever possible, especially through floors, because they create weaknesses in the waterproofing and gas barrier system. Where a penetration is unavoidable, the membrane must be cut neatly and sealed carefully. The detail may require Newton CDM Rope, Newton CDM OverTape, membrane patches, Damp Proof Course (DPC) patches, Newton Pipe Collar or Newton Pipe Sleeve, depending on the situation. If a protrusion needs priming, Newton 109-LM may be required to support adhesion of the sealing products. Every penetration should be inspected before finishes are installed, because later access may require disruptive removal of screeds, linings or boards.

Q) Does Newton 508R need protecting from fire?

A) Yes, Newton 508R must be protected from fire by suitable surface finishes. Its reaction to fire classification is Euroclass F, meaning no declared fire performance should be assumed. This is similar to the classification often noted for plastic-based insulation products, which also require protection within the building build-up. In practice, Newton 508R should be covered by appropriate wall, floor or soffit finishes, such as plasterboard systems, screeds or other specified protective layers, depending on the design. If a project requires a higher fire-rated membrane, that must be specified separately. Newton 508R itself should never be left exposed or assumed to provide fire resistance.

Q) How long does Newton 508R Waterproof Membrane last?

A) Newton 508R is guaranteed against deterioration for 30 years and has a stated life expectancy equal to the design life of the building when installed correctly. Newton also notes a service life expectation of at least 100 years when the membrane is specified, installed and protected in accordance with the relevant documentation. However, the product warranty is not the same as a waterproofing guarantee. The waterproofing guarantee is normally provided by the specialist waterproofing contractor and depends on the full system design, installation quality, drainage, pumping, protection and maintenance. Newton 508R is a highly durable membrane, but the performance of the waterproofing system relies on correct design and workmanship.

Q) What maintenance is needed with Newton 508R?

A) Newton 508R itself requires very little direct maintenance once protected behind finishes, but the drainage and pumping system must remain serviceable. Mechanical pumps and drainage channels should be inspected at least once a year by a competent person. Maintenance should include cleaning and descaling the pumping system, checking pump seals, testing impellers, inspecting discharge pipes, removing debris from the sump base, checking electrical connections and flushing Newton CDM BaseDrain or Newton CDM FloorDrain where required. If the system depends on pumps, a reliable power supply is essential, and battery backup may be needed where pump continuity is critical. Future alterations should not puncture the membrane without specialist advice.

Q) Can damaged Newton 508R be repaired?

A) Yes, Newton 508R can be repaired, but repairs must be carried out using the correct Newton CDM products and detailing method. If the wrong stud is drilled, the stud can be cleaned, plugged with Newton CDM Rope and covered with a small patch of Newton CDM OverTape. Clean cuts, piercings, rips and tears can usually be sealed with Newton CDM OverTape, provided the tape bridges the damage with an adequate margin. Larger areas may require a patch of Newton 508R sealed with Newton CDM Joint Tape or Newton CDM OverTape, depending on how the studs align. All surfaces must be clean and dry before repair, and the repair should be inspected before finishes are installed.

Q) What are the main limitations of Newton 508R Waterproof Membrane?

A) The main limitation of Newton 508R is that it must not be used as a standalone waterproof barrier expected to resist hydrostatic pressure by itself. It must be installed as part of a designed Type C cavity drain system with suitable drainage and safe water discharge. It should not be used where water can collect behind or beneath it without a clear route away. It should not be punctured after installation, left exposed to fire, UV, wear or physical damage, or used as a gas barrier unless all laps, joints, penetrations and interfaces are sealed as part of a complete gas-resisting system. Flat soffit use is also restricted and should only be undertaken by experienced contractors.

Q) Why choose Newton 508R Waterproof Membrane over a standard cavity drain membrane?

A) Newton 508R Waterproof Membrane is a strong choice where a more robust 8mm cavity drain membrane is required for demanding below ground waterproofing, loaded floors, vaulted soffits, earth-retained walls or ground gas protection. Compared with standard 8mm membranes, it is heavier and stronger, with excellent long-term compressive stability and strong resistance to chemical and biological attack. It is also independently tested as both a radon gas barrier and hydrocarbon barrier, giving it additional value on contaminated or gas-affected sites. Supported by BBA Certification Number 94/3010 and a 30-year guarantee against deterioration, Newton 508R offers a high level of confidence when used within a properly designed Newton CDM system.

Technical Data Sheet

Newton CDM Installation Manual

Declaration of Performance (DoP)

BBA Certificate