Soudal Silirub EPDM - Neutral Cure EPDM Silicone Sealant

Health & Safety Recommendations

All relevant personal protective equipment (PPE) must be worn during handling and application. This includes gloves, protective clothing, and appropriate eye protection. Users should consult the product label and material safety data sheet (MSDS) before use for full guidance on handling and potential hazards. Standard site hygiene practices should be observed at all times.

Ensure adequate ventilation during application and curing. This product meets the requirements of LEED regarding Low-Emitting Materials, complying with SCAQMD Rule 1168 and USGBC LEED 2009 Credit 4.1 for adhesives and sealants.

Substrate Suitability

Soudal Silirub EPDM adheres effectively to a wide range of building substrates including concrete, aluminium, steel, treated wood, rigid plastics, and EPDM membranes. Substrates must be structurally sound, clean, dry, and completely free from dust, grease, oils, or other contaminants that may hinder adhesion.

However, adhesion is not achieved on polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE, such as Teflon®), bituminous materials, or polycarbonate. For these substrates, alternative products from the Soudal range should be considered. For instance, use Silirub MA for natural stones to avoid staining, or Silirub PC for bonding on polycarbonate surfaces.

As EPDM formulations can vary significantly, a preliminary adhesion and compatibility test is strongly recommended for every project.

Surface Preparation

Porous surfaces should be primed using Soudal Primer 150 to enhance adhesion and surface integrity. Non-porous surfaces such as metals or certain plastics should be prepared with a suitable Soudal Activator or Soudal Cleaner & Degreaser to clean and activate the bonding area.

Before application, ensure that no moisture is present on the surfaces and that any previously applied sealants or contaminants have been removed. It is important to avoid overlapping sealant joints that are exposed to standing water, unless they are already bonded and are being sealed purely for seam finishing.

Application Method

Soudal Silirub EPDM is supplied in 600ml foil packs and must be applied using a compatible 600ml manual foil cartridge gun, such as the Soudal 600ml Manual Foil Cartridge Gun.

Before use, insert the foil pack into the applicator gun, carefully cut the foil tip, and attach the provided nozzle, trimming it at a 45° angle to suit the required joint width. Extrude the sealant smoothly and evenly along the bonding or sealing surface, maintaining steady pressure to avoid air pockets. Apply in a continuous bead and ensure sufficient contact with the substrate.

Immediately after application, before the sealant begins to skin, smooth off the joint using a soapy solution and a suitable tool such as a finishing spatula. This will help to achieve a professional finish and optimal adhesion.

Avoid using metal spatulas on sensitive materials to prevent damage, particularly on coated EPDM or soft substrates. As with all sealants, ensure that adjacent materials are not disturbed during the curing process.

Coverage

As a rule of thumb, a 600ml foil pack should yield approximately 24 linear metres of sealant when applied to a standard 5mm x 5mm joint.

Coverage will vary depending on the joint dimensions and application technique. Larger or deeper joints will naturally reduce the linear coverage per pack. It is important to measure total joint volume accurately before beginning application to ensure that an adequate number of foil packs is available for the project. Always allow for a margin of wastage and tooling losses.

Please refer to our Guide on How To Measure The Number of Tubes Required For the Job.

Joint Dimensions

• Minimum Width for Joints: 10 mm
  
  

• Maximum Width for Joints: 30 mm
  
  

• Minimum Depth for Joints: 10 mm
  
  

• Recommendation Sealing Jobs: Joint Depth = 0.8 x Joint Width.

Finishing

The sealant should be tooled off before skinning begins. This typically occurs within 10 to 20 minutes depending on ambient temperature and humidity. Tooling ensures the sealant is pressed properly into the joint and a smooth, finished appearance is achieved.

Once cured, the sealant forms a durable, permanently elastic joint with excellent weather resistance. However, it should not be used in areas where long-term water immersion is expected, nor for sealing glass in aquarium applications.

Cleaning

Uncured Silirub EPDM should be removed immediately using Soudal Swipex Cleaning Wipes before the sealant cures.

Once cured, the product can only be removed mechanically, for example using Soudal Silicone Remover Gel or specialist tools. Tools and equipment should also be cleaned immediately after use to prevent contamination and ensure longevity.

Other Information

Silirub EPDM must not be used in combination with other reactive joint sealants until the previous product has completely cured. This helps prevent compatibility issues or premature failure.

While the cured sealant is UV and weather resistant, exposure to certain aggressive chemicals, chlorinated hydrocarbons or strong acids may compromise performance. The use of this product is strictly limited to sealing applications involving EPDM membranes and compatible building materials. If used for other purposes, performance cannot be guaranteed.

For structural EPDM membrane overlaps, particularly where long-term water load is expected, mechanical fixing or a separate adhesive solution may be more appropriate. Always store Silirub EPDM in its original packaging in a cool, dry place at temperatures between +5°C and +25°C, away from direct sunlight or frost.

Q) What is Soudal Silirub EPDM and what makes it different from standard silicones?

A) Soudal Silirub EPDM is a specialist, neutral-curing, low-modulus silicone sealant and adhesive formulated specifically for bonding and sealing EPDM membranes. Unlike generic silicones, it delivers primerless adhesion to EPDM itself while also bonding reliably to many construction materials, helping you join membranes to metals, masonry, timber and rigid plastics in one system. The neutral cure is MEKO-free, so it avoids corrosive by-products and supports safer, low-odour working. Once cured, it remains permanently elastic to accommodate daily and seasonal movement in roofing and façade details. Its black, colourfast finish, combined with excellent UV and weather resistance, makes it particularly suited to long-term outdoor exposure on roofs, parapets, upstands and external interfaces.

Q) Where should Soudal Silirub EPDM be used on roofing and façade projects?

A) Use Soudal Silirub EPDM wherever EPDM membranes must be joined, terminated or sealed to adjacent building elements. Typical locations include EPDM-to-EPDM overlaps, perimeter terminations against masonry or timber, upstands, rooflight kerbs, pipe penetrations, outlets, gutter interfaces and façade air- and water-tightness details. It is equally useful for remedial work, such as re-sealing cut-outs, patching small defects and reinstating weather seals after service penetrations. The combination of neutral cure chemistry, strong primerless adhesion to EPDM, and durable elasticity under UV exposure makes it ideal for external envelopes. Always ensure substrates are sound, clean and dry, and detail joints to shed water rather than retain standing water wherever possible.

Q) Is Soudal Silirub EPDM an adhesive as well as a sealant?

A) Yes. Soudal Silirub EPDM functions as both a silicone sealant and an adhesive, providing structural assistance in typical sealing tasks while forming a strong, flexible bond line. It securely bonds EPDM membranes to themselves and to many compatible materials including aluminium, galvanised steel, treated wood, glass and certain rigid plastics. This dual role is especially valuable at perimeters and penetrations where a watertight seal and dependable adhesion are required together. For structural overlaps subject to long-term water load, combine with appropriate mechanical fixing or specify a dedicated membrane adhesive as part of the detail. Always test on project-specific EPDM formulations and finishes, as membrane recipes and surface treatments can vary.

Q) How does the neutral cure of Silirub EPDM help on site?

A) Neutral cure chemistry minimises the risk of corrosion, staining or substrate attack during curing, which is particularly important around metals, coated surfaces and sensitive finishes often present in roof and façade build-ups. With Soudal Silirub EPDM, there is no release of aggressive acetic acid, and the MEKO-free formulation supports healthier working conditions and compliance with low-emission targets. The neutral cure also promotes reliable adhesion on a broader range of construction substrates compared with many acetoxy silicones. Practically, that means fewer primer steps, reduced compatibility concerns at mixed interfaces, and a more predictable result around aluminium flashings, coated steels, timber kerbs and glazing accessories abutting EPDM membranes.

Q) What movement can Soudal Silirub EPDM accommodate once cured?

A) Soudal Silirub EPDM cures to a permanently elastic, low-modulus rubber designed to absorb joint movement caused by temperature swings, wind loading and building settlement. Its elasticity allows the seal to flex repeatedly without cracking or de-bonding, which is vital for EPDM membranes that expand and contract daily in sun and shade. Low modulus means less stress is transferred to joint edges as the assembly moves, supporting long-term adhesion. Correct joint design remains essential: respect the recommended joint dimensions, control depth with backer where required, and tool to a smooth profile that sheds water. Avoid details that trap standing water, as prolonged immersion can challenge any silicone joint over time.

Q) Which substrates are suitable for Soudal Silirub EPDM and which should be avoided?

A) Soudal Silirub EPDM adheres well to EPDM, aluminium, galvanised steel, stainless steel, glass, treated wood, concrete and many rigid plastics when prepared correctly. It is not suitable for polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE) or bituminous materials, and should not be used on polycarbonate; for polycarbonate specify Silirub PC. For natural stone applications where staining must be avoided, use Silirub MA or a suitable alternative. Because EPDM compositions and coatings differ, always perform a project-specific adhesion and compatibility test before full application. If a porous mineral edge is weak or dusty, stabilise with Soudal Primer 150; for non-porous metals and plastics, clean with Soudal Cleaner & Degreaser prior to sealing.

Q) Do I need a primer before using Soudal Silirub EPDM on EPDM membranes?

A) Generally, no primer is required on clean, sound EPDM because Soudal Silirub EPDM is formulated for primerless adhesion to EPDM substrates. However, if the membrane surface is dusty, chalky, factory-powdered, or contaminated with release agents, clean thoroughly and carry out a test bead. On porous mineral edges adjacent to the membrane, prime with Soudal Primer 150 to stabilise friable surfaces and support consistent adhesion. On non-porous metals and rigid plastics, degrease with Soudal Cleaner & Degreaser. Good preparation is critical: remove old sealant, residues and loose material, ensure dry conditions, and design joints to avoid standing water. A quick site test remains the simplest safeguard before committing to full runs.

Q) What joint sizes are recommended for Soudal Silirub EPDM?

A) For sealing work with Soudal Silirub EPDM, follow these guidance values: minimum joint width 10mm, maximum joint width 30mm, minimum joint depth 10mm. As a general recommendation for sealing jobs, set joint depth at approximately 0.8 × joint width to achieve a resilient, flexible bead geometry. Use a suitable PE backer to control depth and prevent three-sided adhesion where gaps are deep or irregular. Maintain straight, well-supported joint edges and ensure the finished bead is smoothly tooled to shed water. Overly thin beads at edges, uncontrolled depths, and three-point adhesion all increase stress at the bond line and can shorten service life in exposed, high-movement locations.

Q) How do I apply Soudal Silirub EPDM from 600ml foil packs?

A) Load the 600ml foil into a compatible applicator such as the Soudal 600ml Manual Foil Cartridge Gun. Cut the foil tip carefully, fit the nozzle, and trim the nozzle at a 45° angle to suit the required bead. Extrude a continuous, even bead with steady pressure to avoid air pockets, keeping the nozzle in contact to push sealant into the joint. Immediately tool the bead before skinning using a suitable spatula; a light soapy solution can aid profiling, but avoid contaminating bond faces. Work methodically around perimeters and penetrations, protecting adjacent finishes with masking. Do not disturb the joint during cure, and detail to shed water rather than trap it.

Q) How quickly does Soudal Silirub EPDM skin and cure?

A) Skin formation typically occurs within 10 to 20 minutes depending on temperature and humidity, so tooling should be completed promptly for a clean, compacted profile. Full cure progresses from the surface inward by moisture reaction and will depend on joint size, airflow and site conditions. Cooler temperatures, low humidity and deep sections slow curing, while warmer conditions with good ventilation accelerate it. Although early skin forms quickly, avoid loading, washing or stressing the joint until sufficient cure has developed through the depth. As with all silicones, curing is not instantaneous; plan installation sequences to allow undisturbed curing, especially on weather-critical details and at horizontal interfaces.

Q) Can Soudal Silirub EPDM be used under permanent water immersion?

A) No. Soudal Silirub EPDM is a weather-resistant, UV-stable silicone for external envelopes, but it is not intended for continuous or long-term water immersion. Design details to shed water and keep joints free-draining, particularly at laps, upstands and penetrations. Avoid creating pockets where water can sit against the bead, as prolonged immersion challenges any silicone joint and may reduce service life. For roof interfaces subject to persistent standing water, consider redesigning falls, adding mechanical support, or pairing the seal with a complementary membrane adhesive or mechanical fixing suitable for submerged stress. Never use this product for aquarium sealing or submerged glazing applications.

Q) What weather and UV resistance can I expect from Silirub EPDM outdoors?

A) Soudal Silirub EPDM is formulated for harsh exterior exposure. It provides excellent resistance to ultraviolet radiation, ozone and general weathering, maintaining elasticity, colour stability and adhesion on roof and façade details over extended service life. The black, colourfast finish helps preserve appearance under sun and rain, and the neutral-cure chemistry resists corrosion around metals. While the seal is highly durable, overall performance still depends on design and preparation: clean, stable edges; correct bead geometry; and avoidance of permanently wet details. Routine visual inspections during maintenance cycles are good practice, allowing early intervention where movement, abrasion or accidental damage has affected joint integrity.

Q) How do I clean and prepare surfaces before bonding EPDM with this sealant?

A) Begin by removing all old mastic, loose residues and contamination from both the EPDM and the adjoining substrate. Wipe non-porous surfaces with Soudal Cleaner & Degreaser and allow to evaporate fully. On porous, friable or chalky mineral edges, stabilise with Soudal Primer 150, applied neatly to the bonding faces only. Ensure surfaces are dry; moisture in the joint can inhibit adhesion and slow cure. Where release powders or anti-tack treatments are present on EPDM, clean thoroughly and test adhesion. Dry-fit complex details before application so beads can be placed continuously and tooled promptly. Masking edges helps achieve crisp lines and protects sensitive finishes during sealing.

Q) What is the typical coverage from a 600ml foil of Soudal Silirub EPDM?

A) As a practical rule, a 600ml foil yields approximately 24 linear metres of a 5mm × 5mm bead. Real-world coverage depends on joint dimensions, bead shape, substrate flatness and tooling losses. Larger or deeper joints reduce linear yield, and rough or irregular backgrounds demand more material to maintain contact and profile. For reliable estimation, calculate total joint volume (width × depth × length) and include a sensible allowance for start/stop points, overlaps, corners and finishing. Running a small trial on representative details is the quickest way to verify bead size, spacing and consumption before committing full quantities, ensuring sufficient foils are available to complete uninterrupted runs.

Q) Can Soudal Silirub EPDM be used alongside other sealants or adhesives?

A) Yes, but allow the first reactive product to cure completely before applying another reactive sealant nearby. Direct contact between uncured products can lead to compatibility issues, softening or adhesion loss. If you must interface with different chemistries, separate the systems physically within the detail. Always respect known incompatibilities: avoid polycarbonate (use Silirub PC), avoid natural stone staining risks (use Silirub MA or a specified stone-safe alternative), and avoid PE, PP, PTFE and bituminous surfaces. Where a membrane overlap is structurally critical or subject to long-term water load, supplement the silicone seal with mechanical fixing or a suitable EPDM adhesive specified for the duty.

Q) What are the key limitations and ‘do not use’ cases for Soudal Silirub EPDM?

A) Do not use on polyethylene, polypropylene, PTFE or bituminous substrates, and do not use on polycarbonate glazing (use Silirub PC). Avoid natural stone where staining can occur; select Silirub MA or another stone-safe option. Do not specify for continuous water immersion or aquarium applications. Because EPDM formulations and surface treatments differ, always conduct adhesion tests on the actual membrane in use. Avoid three-sided adhesion by controlling depth with backer materials. Do not overlap uncured reactive sealants, and keep details free-draining to prevent standing water. If long-term structural loads act on laps, supplement with mechanical fixings or an appropriate EPDM adhesive.

Q) How should Soudal Silirub EPDM joints be tooled and finished?

A) Immediately after gunning, tool Soudal Silirub EPDM to compact the bead against both sides of the joint and produce a smooth, slightly convex or neatly filleted profile that sheds water. Use a suitable spatula; a light soapy solution can aid glide, but keep finishing solution off the bond faces to avoid edge contamination. Remove masking tape straight after tooling while the sealant is still wet. Avoid using metal tools on sensitive or coated substrates that could scratch. Finish in manageable lengths so you complete tooling before skinning begins. Protect fresh joints from dust, rain and mechanical disturbance until sufficient cure has developed through the depth.

Q) What PPE and site practices are recommended when applying this product?

A) Wear suitable gloves and eye protection, follow normal site hygiene, and work in well-ventilated conditions—especially in plant rooms, confined areas or long continuous runs where moisture must dissipate during cure. Read the label and Safety Data Sheet before use. Keep the area tidy to prevent slips on roofs and around penetrations, and organise access so you can apply continuous beads without stepping across uncured joints. Soudal Silirub EPDM is MEKO-free and compliant with low-emission criteria (e.g., SCAQMD Rule 1168), supporting healthier indoor air quality. Store foils sealed, away from heat and frost, and dispose of empty packaging, wipes and masking responsibly.

Q) How do I remove spills and excess Soudal Silirub EPDM during installation?

A) Clean as you go. While uncured, wipe excess from tools and non-porous surfaces using Soudal Swipex Wipes or clean cloths dampened with a suitable cleaner, taking care not to smear silicone across visible finishes. Change wipes frequently to avoid spreading residue. Once cured, silicone cannot be dissolved and must be removed mechanically; Soudal Silicone Remover Gel can assist softening residues on many surfaces, but always test first on sensitive coatings and plastics. When replacing failed beads, cut out the old silicone thoroughly, clean and, where necessary, prime porous edges with Soudal Primer 150 before re-sealing. Proper masking and prompt clean-up are the easiest ways to maintain a crisp finish.

Q) Can Soudal Silirub EPDM be painted after curing?

A) No. As with other silicones, cured Soudal Silirub EPDM is not paintable. Paints rarely adhere well to silicone and will often crack or flake as the joint moves. Plan colour and appearance at specification stage: the product is supplied in black, which matches EPDM membranes and roof details cleanly. Where a coloured finish is required across a joint, consider detailing that hides the seal behind trims or specify an alternative compatible, paintable system for that particular interface. Attempting to overcoat cured silicone generally leads to maintenance issues, so it is better to design the joint to remain exposed and rely on the colourfast, UV-stable black finish.

Q) What storage and handling advice applies to the 600ml foil packs?

A) Store Soudal Silirub EPDM foils in their original packaging in a cool, dry place between +5°C and +25°C, away from direct sunlight and frost. Keep foils sealed until use to prevent premature curing at the nozzle. When loading into the Soudal 600ml Manual Foil Cartridge Gun, avoid puncturing the foil except at the dispensing tip and ensure the nozzle is cut cleanly for predictable bead size. After short pauses, purge any partially skinned material from the nozzle before continuing. As with all silicones, opened packs should be used promptly for consistent extrusion and performance. Rotate stock using first-in-first-out to maintain shelf-life integrity.

Q) How do I ensure long-term reliability when using Soudal Silirub EPDM?

A) Start with diagnosis and design: confirm the joint’s purpose, movement and water exposure, and detail it to shed water. Prepare surfaces meticulously—clean, degrease or prime as required with Soudal Cleaner & Degreaser and Soudal Primer 150. Control joint geometry with backer to avoid three-sided adhesion, gun a continuous bead, and tool immediately for full contact and a water-shedding profile. Keep uncured joints protected, and allow adequate curing time before loading. Respect material limits—avoid PE, PP, PTFE, bitumen and polycarbonate (specify Silirub PC), and test adhesion on the exact EPDM. For critical overlaps under persistent load or water, pair the seal with mechanical fixing or a suitable EPDM adhesive.

Technical Data Sheet

Safety Data Sheet