Soudal Soudalead Pb - Lead Sealant

Health & Safety Recommendations

Read the packaging label and Safety Data Sheet before use, and follow normal site hygiene throughout application and curing. Wear suitable gloves and eye protection, avoid prolonged skin contact, and keep the working area well ventilated, particularly when sealing in confined roof voids, service zones, plant areas, or enclosed internal spaces. If uncured Soudal Soudalead PB comes into contact with the skin, remove it promptly and wash with soap and water. If it gets into the eyes, rinse immediately with plenty of clean water and seek medical advice if irritation persists.

Because Soudal Soudalead PB is commonly used in exposed roofing and flashing work, take extra care with access, weather conditions, and surface stability before starting. Keep the work area tidy, protect surrounding finished surfaces from contamination, and avoid unnecessary smearing of sealant onto visible faces of lead, brickwork, stone, coated metals, PVC profiles, or glazing elements. Good housekeeping during application makes a major difference to both finish quality and clean-up.

Substrate Suitability

Soudal Soudalead PB is a low modulus neutral cure silicone sealant developed for lead and other metal sealing applications, and it adheres well to many usual building substrates when they are correctly prepared. It is particularly suited to lead flashing details, guttering, downpipes, venting, metal roofing interfaces, and movement joints between lead and surrounding construction materials such as brick, stone, concrete, treated timber, metal, PVC profiles and glass, provided the detail is suitable and compatible.

It does not have good adhesion to PE, PP, PTFE (Teflon®) or bituminous substrates. Direct contact with the secondary sealing of insulating glass units and the PVB film of safety glass must also be avoided. Because finishes and coatings vary widely, especially on aluminium lacquers, textured coatings and PVC, adhesion tests should be carried out before full application. Do not use on polycarbonate, use Silirub PC. Do not use on natural stones such as marble or granite where staining is a concern, use Silirub MA or Fix ALL Flexi. Do not use on bitumen, use Soudal Soudafalt. For EPDM, use Silirub EPDM.

Surface Preparation

For reliable long-term sealing, the substrate must be rigid, clean, dry, and free from dust, grease, oil, oxidation residue, loose particles and any contamination that may interfere with adhesion. In roofing and flashing work, this means making sure the chase, joint edges and surrounding surfaces are sound before the sealant is applied. Weak mortar, flaking paint, dirt build-up, old failing sealants and loose debris should be removed fully before resealing.

Porous surfaces should be primed with Soudal Primer 150 where required. If needed, non-porous surfaces can be prepared with Soudal Cleaner & Degreaser or Soudal Multi Cleaner. Allow cleaning agents to flash off fully before applying the sealant. Good preparation is especially important where Soudalead PB is being used between dissimilar materials, as poor surface condition can lead to early adhesion loss at the joint edges.

Application Method

Apply Soudal Soudalead PB with a caulking gun, keeping the nozzle size matched to the joint dimensions so the bead fills the joint properly without excessive overflow. Gun the sealant into the joint steadily and continuously so it wets both sides fully and avoids trapped air. The aim is to produce a continuous, well-compacted seal that contacts the joint faces evenly from end to end.

Finish the bead before skinning begins. Under normal conditions, skin formation occurs in around 6 minutes, so tooling should be carried out promptly and in short, manageable lengths. Finish with a soapy solution, but make sure the joint edges are not touched by the solution, as contamination of the adhesion surfaces can cause the sealant not to adhere properly. For that reason, it is better to dip only the finishing tool in the soapy solution rather than applying the solution directly across the surrounding surfaces. It is also best not to apply the soapy solution in full sunlight, as it can dry too quickly and make finishing more difficult.

Joint Dimensions

Correct joint geometry is essential if Soudal Soudalead PB is expected to perform as a flexible weatherproof seal. The minimum joint width is 5mm, the maximum joint width is 30mm, and the minimum joint depth is 5mm. As a general rule for sealing work, joint width should be 2x joint depth. This helps the cured sealant stretch and recover properly under movement without becoming overstressed.

Three-point adhesion should be avoided at all times, as it restricts the elastic movement of the sealant and increases the risk of failure. A suitable backing material should be used where necessary to control depth and ensure the sealant bonds only to the two intended joint faces. Joints that are too small can also cause problems, because if movement is too great for the joint size, the silicone can be pulled away from the sides during service.

Coverage

Coverage depends on joint width, joint depth, and how consistently the bead is applied and tooled. Smaller joints naturally provide greater linear coverage per cartridge, while wider or deeper joints reduce the total run achievable. On roofing and flashing work, usage can also vary depending on how rough or absorbent the surrounding surfaces are and how much sealant is needed to achieve a full compacted fill.

For practical estimating, use the Platinum Chemicals Sealant Estimate Calculator. This is the best way to calculate likely cartridge demand from the actual joint dimensions being sealed, rather than relying on a generic figure that may not reflect the job in hand.

Curing Time

Soudal Soudalead PB cures by moisture curing and forms a skin in approximately 6 minutes under normal conditions. Cure speed is around 2mm/24h, although actual curing will vary depending on temperature, humidity, ventilation and bead size. Thicker joints and colder conditions will extend the time needed for the sealant to cure right through.

Once cured, the sealant remains permanently elastic and is capable of accommodating movement up to ±20%, which is one of the key reasons it is well suited to lead flashing and external metal joint work. It also retains flexibility across a wide service temperature range from -60°C to +120°C, helping it cope with both severe winter exposure and strong solar heat on external building details.

Cleaning

Clean uncured Soudal Soudalead PB immediately using Soudal Swipex Cleaning Wipes. Prompt clean-up is important because once curing begins, smears on visible surfaces become harder to remove neatly without affecting the finish. Keep tools, nozzles and surrounding surfaces clean as work progresses so partially skinned material is not dragged across the joint edges or onto adjacent materials.

Once cured, the product can only be removed mechanically, with aid from Soudal Sealant Remover Spray or Soudal Silicone Remover Gel where appropriate. Removal of cured silicone should always be carried out carefully on decorative surfaces, lead finishes, coated metals, glazing and plastics, as mechanical scraping can mark the substrate more easily than the sealant itself.

Limitations

Soudal Soudalead PB is not suitable for PE, PP, PTFE (Teflon®) or bituminous substrates. Do not use on polycarbonate, use Silirub PC. Do not use on natural stones such as marble or granite where staining is a concern, use Silirub MA or Fix ALL Flexi. Do not use on bitumen, use Soudal Soudafalt. Do not use for bonding aquariums, use Silirub AQ. Do not use in applications where continuous water immersion is possible.

Direct contact with the secondary sealing of insulating glass units and the PVB film of safety glass must be avoided. Contact with bitumen, tar and other plasticiser releasing materials such as EPDM, neoprene and butyl should also be avoided, as this can lead to discoloration and loss of adhesion, for EPDM use Silirub EPDM. When using different reactive joint sealants in the same area, the first joint sealant must be completely hardened before the next one is applied.

Other Information

Soudalead PB is designed for lead compatible, weather resistant sealing and offers very good resistance to UV, moisture and ageing, but some colour changes can still occur under certain conditions. A total absence of UV can cause a colour change, and in an acid environment or in a dark room, a white sealant can slightly turn yellow. Under the influence of sunlight it will usually turn back towards its initial colour. Discoloration can also occur through exposure to chemicals, high temperatures or prolonged UV radiation.

For best results, apply within the recommended application temperature range of +5°C to +35°C and make sure the joint is properly designed, prepared and tooled before skinning begins. The cured sealant remains soft and highly elastic, with a low modulus character that makes it especially suitable for lead flashing, roofing details, gutters, downpipes and movement joints between dissimilar materials where a flexible, durable exterior weather seal is required.

Q) What is Soudal Soudalead PB?

A) Soudal Soudalead PB is a premium low modulus neutral cure silicone sealant developed specifically for sealing lead and other metal details in roofing, flashing and general exterior building work. It is designed for joints that need to stay flexible for the long term rather than hardening and failing after repeated movement or weather exposure. Soudal Soudalead PB is compatible with all common lead types, including milled, cast and rolled lead, which makes it particularly useful for specialist flashing and roofline details. Once cured, it remains permanently elastic, colour stable and highly weather resistant, helping provide a durable professional seal on exposed external joints where ordinary general-purpose sealants may be a weaker choice.

Q) What is Soudal Soudalead PB used for?

A) Soudal Soudalead PB is used for sealing lead flashing, roofing joints and metal interfaces where long-term flexibility and weather resistance are essential. One of its main uses is sealing lead flashing into brick, stone and concrete chases so water cannot track behind the flashing. It is also suitable for joints on gutters, downpipes, venting and metal roofing sheets, as well as seals between lead and treated wood, metal, PVC profiles or glass. Because Soudal Soudalead PB is a low modulus neutral cure silicone, it is especially useful on movement joints between dissimilar materials. That makes it a strong choice for both new construction and remedial maintenance work in exposed exterior conditions.

Q) Why is Soudal Soudalead PB better suited to lead than a standard silicone sealant?

A) Soudal Soudalead PB is specifically formulated for lead and related metal sealing applications, which is the key difference between it and many ordinary silicone sealants. Not all silicones perform well long term on lead surfaces, especially where constant movement, moisture and temperature changes are involved. Soudal Soudalead PB is compatible with all common lead types and uses a low modulus neutral cure formulation that helps reduce stress within the joint. That softer, more movement-tolerant cured profile is important because lead expands and contracts significantly with temperature changes. In practical terms, Soudal Soudalead PB is designed for exactly the kinds of flashing and roofing details where a standard general-purpose silicone may prove less reliable.

Q) Can Soudal Soudalead PB be used on all types of lead?

A) Yes, Soudal Soudalead PB is suitable for all common lead types, including milled, cast and rolled lead. This is one of its most important advantages because compatibility with lead is essential in flashing and roofing work. If a sealant is not properly suited to lead, it may lose adhesion, become stressed by movement or fail earlier than expected in exterior exposure. Soudal Soudalead PB has been developed specifically for those conditions, so it gives much greater confidence in traditional and modern lead detailing. Whether the job involves new flashing installation, repair work, lead to masonry joints or lead around roof penetrations, Soudal Soudalead PB is intended to give a durable and movement-tolerant seal.

Q) Is Soudal Soudalead PB suitable for sealing lead flashing into brick, stone or concrete?

A) Yes, sealing lead flashing into brick, stone or concrete is one of the main intended uses of Soudal Soudalead PB. In flashing work, the sealant needs to bond well to both the lead and the surrounding masonry while remaining flexible enough to absorb movement over time. Soudal Soudalead PB is designed for exactly that kind of application. It provides very good adhesion on common construction materials and remains permanently elastic after curing, which helps it cope with temperature changes, building movement and external weather exposure. For roofers and builders, this makes it a dependable option for sealing flashing chases and maintaining a long-lasting weatherproof junction in exposed exterior conditions.

Q) Can Soudal Soudalead PB be used on gutters, downpipes and venting?

A) Yes, Soudal Soudalead PB is suitable for sealing joints on gutters, downpipes and venting where a flexible, weather-resistant seal is needed. These kinds of details are constantly exposed to moisture, outdoor temperature changes and small amounts of movement, so a rigid or unsuitable sealant can fail quite quickly. Soudal Soudalead PB remains permanently elastic and offers excellent moisture resistance, which makes it well suited to those demands. It is also compatible with many metals and common construction substrates, so it can be used across a wide range of external joint details. For maintenance and new installation work alike, Soudal Soudalead PB is a strong option where long-term exterior sealing performance matters.

Q) Is Soudal Soudalead PB suitable for metal roofing sheets and exterior metal joints?

A) Yes, Soudal Soudalead PB is suitable for sealing metal roofing sheets and a wide range of exterior metal joints where flexibility and weather resistance are important. Metal joints are often subject to daily expansion and contraction, particularly in exposed roof areas, so the sealant must remain soft enough to cope with that movement rather than cracking or pulling away. Soudal Soudalead PB has a low modulus neutral cure formulation, which helps it handle those conditions more effectively. It also offers excellent UV resistance, moisture resistance and good long-term ageing performance, making it highly suitable for exposed external applications. In roofing and sheeted metal details, that balance of adhesion and flexibility is especially valuable.

Q) Why does the low modulus formulation of Soudal Soudalead PB matter?

A) The low modulus character of Soudal Soudalead PB matters because it allows the cured sealant to move more easily with the joint instead of putting excessive stress on the bond line. This is especially important in lead flashing, roofing joints and mixed-material details, where expansion and contraction can be significant. Lead, metal, masonry and timber all behave differently with temperature and moisture changes, so a stiffer sealant may be more likely to tear at the edges or lose adhesion over time. Soudal Soudalead PB is designed to remain soft and flexible enough to absorb that movement while still maintaining a weatherproof seal. That is one of the main reasons it suits exposed exterior building work so well.

Q) Does Soudal Soudalead PB stay flexible after curing?

A) Yes, Soudal Soudalead PB remains permanently elastic after curing, and that is one of its biggest strengths. In roofing and flashing work, the joint is rarely static for long. Daily temperature change, seasonal movement, wind loading and general building settlement all place stress on the seal. If the sealant hardens too much, it can crack, split or pull away from the substrate. Soudal Soudalead PB is designed to avoid that by curing to a soft, low modulus silicone rubber that can stretch and recover repeatedly. This permanent flexibility makes it much more suitable for flashing, gutters, metal interfaces and other exterior joints than a rigid filler or a sealant with lower movement tolerance.

Q) How weather resistant is Soudal Soudalead PB?

A) Soudal Soudalead PB is highly weather resistant and is designed specifically for exposed exterior applications. It offers excellent resistance to UV, moisture and ageing, which is essential for flashing, guttering and metal joints that are continually exposed to sun, rain and temperature cycling. Over time, poor-quality sealants can harden, fade, crack or lose adhesion, particularly in roofline positions where exposure is severe. Soudal Soudalead PB is formulated to resist those effects and maintain long-term performance. Its permanent colour stability after curing also helps visible joints look cleaner and more consistent for longer. In practical terms, it is a specialist exterior sealant built to cope with harsh building envelope conditions.

Q) Is Soudal Soudalead PB good for high movement joints?

A) Yes, Soudal Soudalead PB is a strong choice for movement joints, particularly where different materials meet and flexibility is essential. It can accommodate movement up to ±20%, which makes it well suited to lead interfaces, metal roof details, gutter joints and other exterior construction joints that expand and contract over time. The low modulus neutral cure formulation helps the sealant flex more easily rather than fighting against the movement. That is especially important where lead is sealed against brick, stone, concrete, treated timber or PVC profiles, because those materials all behave differently in service. Soudal Soudalead PB is designed to stay elastic and recover well, helping maintain a durable weather seal across changing conditions.

Q) What surfaces does Soudal Soudalead PB adhere to?

A) Soudal Soudalead PB adheres well to many metals and common building substrates when they are properly prepared. Its main strength is sealing lead, but it is also suitable for interfaces involving brick, stone, concrete, treated wood, metal, PVC profiles and glass in the right construction details. That makes it a versatile option for flashing, roofing and general exterior movement joints where more than one material is involved. However, as with any specialist sealant, proper preparation and a compatibility check are important where the surface finish is unfamiliar. Soudal Soudalead PB is intended for demanding external sealing work, but the reliability of the joint still depends on the quality, cleanliness and stability of the substrates it is applied to.

Q) What surfaces should not be sealed with Soudal Soudalead PB?

A) Soudal Soudalead PB is not suitable for PE, PP, PTFE or bituminous substrates, as adhesion on those materials is unreliable. It should also not be used on polycarbonate, where Silirub PC is the correct option. For natural stone such as marble or granite where staining is a concern, Silirub MA or Fix ALL Flexi is the more appropriate choice. Soudal Soudalead PB should also be kept away from direct contact with the secondary sealing of insulating glass units and the PVB film of safety glass. Contact with bitumen, tar and plasticiser-releasing materials such as EPDM, neoprene and butyl should also be avoided. Where EPDM is involved, Silirub EPDM should be used instead.

Q) How should surfaces be prepared before applying Soudal Soudalead PB?

A) Surfaces should be rigid, clean, dry and free from dust, grease, oil, oxidation residue, loose particles and old failing sealants before Soudal Soudalead PB is applied. In lead flashing work, this means the chase and surrounding masonry need to be sound and properly cleaned so the new seal can bond reliably. On porous surfaces, Primer 150 should be used where required. On non-porous surfaces, Soudal Cleaner & Degreaser or Soudal Multi Cleaner may be appropriate depending on the substrate. Good preparation is essential because even a high-quality sealant will not perform properly if it is applied onto weak, dirty or unstable surfaces. With Soudal Soudalead PB, preparation has a direct effect on both finish quality and long-term seal durability.

Q) How do you apply Soudal Soudalead PB properly?

A) Soudal Soudalead PB should be applied with a caulking gun using a nozzle size suited to the joint. The sealant should be gunned steadily into the joint so it wets both sides fully and forms a continuous, well-compacted bead without trapped air. Because skin formation is around 6 minutes under normal conditions, tooling should be carried out promptly and only in manageable lengths. A soapy solution can be used for finishing, but it should not contaminate the actual adhesion faces of the joint, as that may affect bond quality. It is better to dip only the tool rather than flooding the joint area. With Soudal Soudalead PB, clean bead control and prompt tooling are the keys to a neat and durable finish.

Q) What joint size is recommended for Soudal Soudalead PB?

A) Soudal Soudalead PB is recommended for joints with a minimum width of 5mm, a maximum width of 30mm and a minimum depth of 5mm. As a general sealing rule, the joint width should be about 2x the joint depth. This helps the cured sealant move correctly without becoming overstressed. If the joint is too narrow, the movement may be too great for the available sealant section and the bead can pull away from the sides. If the joint is too deep, unnecessary material is used and movement performance may suffer. Three-point adhesion should also be avoided, so a suitable backing material should be used where needed. Proper joint design is an important part of getting the best from Soudal Soudalead PB.

Q) How quickly does Soudal Soudalead PB skin and cure?

A) Soudal Soudalead PB forms a skin in approximately 6 minutes under normal conditions, which means finishing should be carried out fairly quickly after application. Cure speed is around 2mm per 24 hours, although this will vary depending on temperature, humidity, ventilation and bead size. Thicker joints and colder or less ventilated conditions will naturally slow the cure. Once fully cured, Soudal Soudalead PB remains permanently elastic and can cope with temperatures from -60°C to +120°C, which makes it highly suitable for exposed exterior service. In practical terms, it offers a good balance between workable tooling time and dependable through-cure, provided the job is planned properly and the joint is not disturbed too early.

Q) Can Soudal Soudalead PB be used in very cold or very hot service conditions?

A) Yes, once cured, Soudal Soudalead PB has a service temperature range from -60°C to +120°C, which means it can cope with very cold winter conditions and strong summer heat on exposed exterior joints. That is especially important in roofline and flashing work, where dark surfaces and direct sun can cause major thermal movement. It also means the sealant remains stable in harsh climates and demanding external service environments. Application, however, should still be carried out within the recommended range of +5°C to +35°C. So while cured Soudal Soudalead PB is highly tolerant of temperature extremes, good installation practice still matters if you want the joint to perform properly from the start.

Q) How do you clean Soudal Soudalead PB?

A) Uncured Soudal Soudalead PB should be cleaned immediately using Soudal Swipex Cleaning Wipes. This is the easiest stage to remove smears and excess material cleanly, particularly on visible lead, coated metals, glazing and surrounding finishes. Once the sealant has cured, it can only be removed mechanically, with help from Soudal Sealant Remover Spray or Soudal Silicone Remover Gel where appropriate. Mechanical removal should be done with care because scraping can easily mark decorative or sensitive surfaces. As with most silicone work, prevention is better than cure. Careful gunning, controlled tooling and prompt clean-up during application make a much bigger difference to the final appearance than trying to correct cured residue afterwards.

Q) What are the main limitations of Soudal Soudalead PB?

A) The main limitations of Soudal Soudalead PB are that it is not suitable for PE, PP, PTFE, bituminous substrates, polycarbonate, aquarium bonding or continuous water immersion. It should also not be used where it would come into direct contact with the secondary sealing of insulating glass units or the PVB film of safety glass. While it is excellent for lead and many external metal details, it is not a universal sealant for every substrate. It must also be kept away from tar, bitumen and plasticiser-releasing materials such as EPDM, neoprene and butyl, as these can cause adhesion problems and discoloration. Soudal Soudalead PB performs best when used within its intended role as a specialist lead-compatible exterior sealant.

Q) Why choose Soudal Soudalead PB for roofing and flashing work?

A) Soudal Soudalead PB is worth choosing for roofing and flashing work because it combines the key properties that those details actually need. It is compatible with all common lead types, remains permanently elastic, has excellent UV and weather resistance, and offers very good adhesion on many metals and common construction materials. It is also low modulus, which means it copes well with the constant expansion and contraction seen in exposed lead and metal joints. Added to that, Soudal Soudalead PB is easy to apply, easy to tool, colour stable after cure and formulated with a modern MEKO free chemistry. For professional flashing and roofline sealing, it is a purpose-made product rather than a general compromise.

Technical Data Sheet

Declaration of Performance (DoP)

Safety Data Sheet