Soudal Silirub LMN Silicone Sealant – Low Modulus Neutral Cure Silicone for Construction & Glazing

Soudal Silirub LMN Silicone Sealant is a high‑quality, low modulus, neutral cure
silicone designed for flexible, durable sealing in construction and glazing joints.
Its non‑corrosive, low odour formula offers excellent adhesion to a wide range of
materials, making it ideal for perimeter sealing around windows and doors, façade joints,
curtain walling and general building joints both inside and out.

Soudal Silirub LMN Silicone Sealant is a one‑component, low modulus,
neutral cure (LMN) silicone that cures under the influence of atmospheric moisture
to form a permanently elastic, durable rubber. It is specifically formulated for
high‑movement joints in construction and glazing, where a combination of
flexibility, long‑term weather resistance and substrate compatibility is crucial.

As a neutral curing silicone, Silirub LMN does not release corrosive acids
during cure, making it suitable for use on metals (including aluminium, galvanised
steel and zinc), concrete, brickwork, plaster, many plastics and coatings that may be
sensitive to acetoxy (vinegar‑cure) systems. Its low modulus means that the
sealant exerts lower stress on joint sides while accommodating a relatively high
degree of movement, ideal for façade expansion joints, perimeter sealing and
window/door installations.

Typical Use Cases

• Perimeter sealing of windows and doors – between frames and masonry, concrete, brickwork or cladding in both residential and commercial buildings.
• Façade & curtain wall joints – movement joints between concrete panels, brickwork, metal panels and curtain wall frames.
• Glazing applications – as a weatherseal in glazing systems and for sealing around glazing beads (follow system manufacturer guidance).
• Partition and cladding joints – sealing internal and external joints between partition elements or cladding panels.
• General construction joints – low modulus sealing of connection joints, movement joints and corner junctions in building envelopes.

Usage & Application Tips

• Surface preparation:
  • Substrates must be clean, dry, and free from dust, grease, oil, laitance and loose particles.
  • Remove any old or failing sealant completely using a mechanical scraper and, if needed, a suitable sealant remover.
  • Degrease non‑porous substrates (e.g. metals, glass, coated surfaces) with an appropriate cleaner and lint‑free cloth.
• Priming:
  • Silirub LMN generally offers excellent adhesion without primer on many common substrates.
  • On highly porous or critical surfaces (e.g. very absorbent concrete, friable masonry), consult the Soudal datasheet for primer recommendations and perform adhesion tests.
• Joint design:
  • Follow good practice for joint design in accordance with EN 15651 and façade/glazing recommendations.
  • Use a closed‑cell PE backing rod or bond‑breaker tape to avoid three‑sided adhesion and to control joint depth.
  • Typical joint width‑to‑depth ratios are often around 2:1 (e.g. 20 mm wide × 10 mm deep), but always follow project specifications.
• Application:
  • Cut the cartridge tip, screw on the nozzle and trim the nozzle at an angle to match the joint width.
  • Place the cartridge into a quality sealant gun and apply even, continuous pressure to fill the joint fully, avoiding air pockets.
  • Ensure the sealant makes complete contact with both joint sides and the backing material.
• Tooling & finishing:
  • Tool Silirub LMN within the skin‑forming time using a spatula or profiling tool lightly wetted with a suitable smoothing liquid.
  • Form a slightly concave joint profile for better movement capability and water shedding.
  • Remove any masking tape immediately after tooling, before a skin forms.
• Curing:
  • Silirub LMN cures by reacting with atmospheric moisture; typical cure rate is around 2–3 mm per 24 hours at 23 °C and 50% RH (see datasheet).
  • Do not expose the joint to continuous water immersion or heavy cleaning until fully cured.
• Clean‑up:
  • Remove uncured sealant from tools and adjacent surfaces with a suitable Soudal cleaner or white spirit immediately after use.
  • Cured silicone can only be removed mechanically (cutting, scraping, carefully with a knife or scraper).
• Important limitations:
  • Like most silicones, Silirub LMN is generally not paintable – select the appropriate colour for visible joints.
  • Not recommended for aquariums, bituminous substrates, natural stone prone to staining (e.g. some marbles) or on plastics that bleed plasticisers without specific testing.
  • For specialist applications (e.g. structural glazing, fire‑rated joints), use dedicated Soudal systems with the correct approvals.

Technical & Performance Overview

Soudal Silirub LMN Silicone Sealant is a professional low modulus neutral silicone
typically tested and classified in accordance with EN 15651 for façade and glazing
sealants (e.g. EN 15651‑1 F‑EXT‑INT CC, EN 15651‑2 G, depending on the declared use).
For precise values, always refer to the current technical datasheet and Safety Data Sheet
(SDS).

• Chemistry: One‑component, neutral cure, low modulus silicone (LMN).
• Modulus & movement: Low modulus elastic sealant with high movement capability, suitable for expansion and connection joints (see EN 15651 classification for movement class).
• Curing mechanism: Moisture‑curing; vulcanises into a permanently elastic silicone rubber.
• Consistency: Thixotropic, non‑sag on vertical joints.
• Service temperature range: Typically around ‑40 °C to +150 °C once cured (verify in current datasheet).
• Weather & UV resistance: Excellent – silicone rubber is highly resistant to UV, ozone, moisture and ageing.
• Adhesion: Very good adhesion to concrete, brickwork, plaster, render, metals (aluminium, galvanised steel, zinc, stainless), glass, many plastics and coated surfaces (always test for critical projects).
• Colours: Commonly supplied in white, grey, black and other façade/glazing colours (check available colour range with your supplier).
• Paintability: Not generally paintable – joint colour must be chosen to suit the application.
• Indoor / outdoor use: Suitable for internal and external joints on compatible substrates.
• Packaging: Standard cartridges (e.g. 290–300 ml) for use with a sealant gun; also available in other formats depending on region.
• Storage: Store in original unopened packaging in a cool, dry place, away from heat sources and direct sunlight; observe expiry dates.
• Safety: Neutral cure – low odour and non‑corrosive, but always use with adequate ventilation and PPE as indicated in the SDS.

Soudal Silirub LMN Silicone Sealant Features & Customer Benefits

• Low modulus for high‑movement joints
  Designed to handle significant expansion and contraction in façade and perimeter
  joints, reducing the risk of joint failure over time.
• Neutral cure – safe on sensitive substrates
  Non‑corrosive to most metals and compatible with concrete, brick and many coatings,
  unlike some acetoxy silicones that can attack or stain certain materials.
• Excellent adhesion to porous and non‑porous surfaces
  Ideal for mixed‑material construction where masonry, metal, glass and plastics
  meet in a single joint, such as modern façade systems.
• Outstanding durability outdoors
  High resistance to UV, weather and ageing ensures long service life in exposed
  external joints on façades and glazing.
• Easy to gun and finish
  Smooth application and tooling help installers achieve clean, professional‑looking
  joints consistently on site.

Frequently Asked Questions – Soudal Silirub LMN Silicone Sealant

1. What is the difference between Silirub LMN and standard acetoxy silicones?

Silirub LMN is a low modulus neutral cure silicone, whereas acetoxy
silicones release acetic acid (vinegar‑like smell) during curing. Key differences:

• Neutral cure – non‑corrosive to most metals and more compatible with concrete, brick, stone and sensitive substrates.
• Low modulus – better suited to high‑movement joints in façades and perimeter seals.
• Lower odour – more pleasant to use in occupied buildings.

Acetoxy silicones are often used for simple glazing or sanitary work on fully
non‑porous substrates, whereas Silirub LMN is preferred for construction and façade
joints requiring movement and substrate versatility.

2. Is Silirub LMN suitable for exterior façade and expansion joints?

Yes. Silirub LMN is specifically formulated as a low modulus façade and glazing
sealant, making it suitable for:

• Façade expansion and connection joints.
• Perimeter joints around windows and doors in external walls.
• Joints between cladding or curtain wall elements.

Always design joints in accordance with EN 15651, façade design standards and
project‑specific movement requirements, and follow Soudal’s technical guidance.

3. Can Silirub LMN be used on natural stone?

As with most silicones, there is a risk of edge staining or discolouration on
some natural stones (e.g. marble, limestone) due to migration of oils or plasticisers.
For natural stone applications:

• Use a silicone specifically approved for natural stone from the Soudal range.
• Always perform a stain test on an off‑cut or hidden area before large‑scale use.

4. Can Silirub LMN be painted?

No. Like most silicone sealants, Soudal Silirub LMN is not paintable with
conventional decorative paints. Paint tends not to adhere well and may crack or
flake from the flexible silicone surface.

The best approach is to:

• Choose the correct colour of Silirub LMN at installation, or
• If a paintable joint is essential, use a paintable hybrid or acrylic sealant
  specified by Soudal for that purpose.

5. Is Silirub LMN suitable for internal use as well as external?

Yes. Silirub LMN is suitable for both internal and external joints. The neutral
cure, low odour formulation makes it well‑suited to internal use in:

• Partition joints and connection joints.
• Perimeter seals around internal windows and doors.
• General building joints where a permanently elastic seal is needed.

Ensure good ventilation during curing and follow normal safety practices.

6. Common Uses & How to Use Soudal Silirub LMN Silicone Sealant

Common Uses:

• Perimeter sealing between window/door frames and masonry or cladding.
• Façade expansion joints in concrete, brick or panel systems.
• Glazing weatherseals around glass and frame interfaces (non‑structural).
• Connection joints between prefabricated elements, cladding and curtain walling.
• General building and partition sealing where movement must be accommodated.

How to Use – Step‑by‑Step:

1. Confirm substrate compatibility by reviewing the technical datasheet and, if necessary, performing adhesion tests.
2. Remove any old sealant and thoroughly clean and dry the joint; degrease non‑porous surfaces.
3. Insert backing rod or apply bond‑breaker tape to control joint depth and avoid three‑sided adhesion.
4. Mask joint edges if a very neat line is required.
5. Cut the cartridge tip, attach the nozzle and trim to match the joint width; load into a sealant gun.
6. Gun Silirub LMN into the joint in a continuous, even bead, ensuring full contact with both sides and the backing.
7. Tool the joint immediately with a wetted spatula to compact the sealant and form a smooth, concave profile.
8. Remove masking tape while the sealant is still wet and allow to cure undisturbed.
9. Avoid cleaning, painting or stressing the joint until the sealant is fully cured.