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Silicone Sealant
Soudal Silirub in nineteen colours, matched to the roofline we sell.
There are two silicones worth having on a roofline or window job, and they are both Soudal Silirub. One does ninety per cent of the work; the other is the one you reach for when the bead touches glass.
Silirub LMN — 300ml cartridge
Ten colours, all 300ml, matched to the foils we sell the boards in — white board, white tube; Black Ash board, Black tube. This is the range for fascia, soffit, capping, cladding and frame perimeters, and on most jobs it is the only tube you need. If the bead is going anywhere near a sealed unit edge or a laminated pane, stop here and use Silirub 2 below.
Doing a full house? A box of 24 works out 16% cheaper than buying singles — £4.17 a tube against £4.99, and you're not coming down the ladder for one more tube halfway up a gable.
Silirub 2 — 300ml cartridge
Nine colours, all 300ml. This is the one that goes against glass — Soudal have tested it against most insulating-glass edge seals and conventional PVB laminated films, which LMN is not cleared for. It is dearer because it is 100% silicone with no filler in it to shrink back, so it is also the tube for a joint you would rather not be back to in five years.
Box of 15 — 16% cheaper than buying singles. £8.33 a tube against £9.99.
Which one, LMN or Silirub 2?
Both are low modulus neutral cure silicones.
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Low modulus means the bead stretches with the joint instead of fighting it, which is what you want on anything that moves with the weather.
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Neutral cure means no acetic acid, so no vinegar smell, no corroded metal, and no damage to the plastics and coatings a roofline job is full of. Both are rated to ±25% joint movement and both conform to ISO 11600 25LM.
And both are MEKO free, which is on Soudal's own current data sheet. That is not true of every low modulus neutral on the market, and it is the first thing worth checking on a sealant you have not used before.
Silirub LMN — the one most jobs get done with
This is the grade branches stock and the one most roofline and window fitters use day to day. It skins in about seven minutes, grips most surfaces without a primer, and is virtually odourless — which you appreciate more than you would think when you are working in a roof space or a conservatory.
Fascia, soffit, capping, cladding, window and door perimeters. If the bead is sitting against uPVC, timber or masonry, LMN does the job and there is no sense spending more.
✔ Skin formation approx. 7 minutes
✔ ±25% joint movement, elastic recovery over 80%
✔ Elongation at break over 700%
✔ Hardness 24 ± 5 Shore A
✔ Withstands −60°C to +150°C
✔ Conforms to ISO 11600 F+G 25LM
✔ MEKO free
Silirub 2 — when it touches glass, or has to last
The one that goes against glass. Soudal have tested it against most insulating-glass edge seals and conventional PVB laminated films, and Silirub LMN explicitly is not cleared for either — their sheet says so in plain terms. If the bead is going near the edge of a sealed unit or a laminated pane, it is Silirub 2 or nothing, whatever it costs.
Silirub 2 is also 100% silicone. Everything else in a cartridge is filler, and filler is what shrinks back as a joint cures and ages — this has none in it to go anywhere. Softer, stretchier, and good for 30°C more heat than LMN.
✔ Skin formation approx. 9 minutes
✔ ±25% joint movement, elastic recovery over 80%
✔ Elongation at break over 800%
✔ 100% silicone — no filler to shrink back
✔ Withstands −60°C to +180°C
✔ ATG approval, conforms to ISO 11600 F 25LM and G 25LM
✔ MEKO free
The short version
Feature | Silirub LMN | Silirub 2 |
|---|---|---|
Roofline, cladding, frame perimeters | ✔ | ✔ |
Against a sealed unit edge seal | ✘ | ✔ |
Against laminated / PVB glass | ✘ | ✔ |
Skin time | 7 min | 9 min |
Temperature | -60 to +150°C | -60 to +180°C |
Silicone content | 90-95% | 100% |
Neither is paintable, and neither goes on natural stone — Soudal are clear that marble and granite will stain. If you need it to stick as well as seal, or to take paint afterwards, that is a hybrid polymer adhesive rather than a silicone. (Link to the adhesives page.)
Colour matching, matched to the foil, not guessed
This is the bit nobody else bothers with. We sell the roofline as well as the sealant, so we know which tube goes against which board.
Roofline Colour | Use |
|---|---|
White | LMN Brilliant White · Silirub 2 Brilliant White |
Black Ash | LMN Black · Silirub 2 Black |
Anthracite Grey (grained and smooth), RAL 7016 | LMN Anthracite Grey · Silirub 2 Anthracite Grey |
Agate Grey, RAL 7038 | LMN Agate Grey |
Chartwell Green | LMN Chartwell Green |
Cream | LMN Cream |
Golden Oak | LMN Caramel · Silirub 2 Toffee |
Irish Oak | Silirub 2 Oak |
Rosewood | Silirub 2 Rosewood · LMN Teak as the closest in that range |
Mahogany | LMN Brown as the closest match |
Any colour, invisible joint | LMN Clear · Silirub 2 Clear |
Getting a decent finish
A few things off Soudal's own sheets that are worth knowing before you start.
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Joint size matters more than most people think. Minimum 5mm wide and 5mm deep, maximum 30mm wide, and the rule of thumb is joint width equals twice the joint depth. Too deep and the bead cannot stretch; too thin and it tears.
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Prime porous surfaces. Brick, render and bare timber want Soudal Primer 150 first. Non-porous surfaces can be prepared with a Soudal cleaner or activator. On anything unusual, run a test bead somewhere it will not show.
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Tool before it skins — that is seven minutes on LMN and nine on Silirub 2, and less on a warm day. Use finishing solution on the tool, not on the joint: if it runs onto the joint edges the sealant will not adhere there. And do not use it in full sun, because it flashes off too fast and can stain the surface.
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Clean up before it cures. White spirit or Soudal Surface Cleaner while it is wet. Once Silirub 2 has gone off, the only way it is coming off is mechanically.
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Neither will stick to PE, PP, PTFE or anything bituminous, and neither goes on natural stone.
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A standard skeleton gun takes a 300ml cartridge — ours is here. If you are doing a full house, a battery gun is a lot easier on the hand. ▸ Gun listing
FAQ
Is Soudal Silirub MEKO free?
Yes. Both Silirub LMN and Silirub 2 are listed as MEKO free on Soudal's current technical data sheets, revision May 2026. Worth noting MEKO free is not the same as oxime free — both are oxime cure, Soudal simply use an oxime other than MEKO.
Can I paint over it?
No. Soudal state Silirub 2 is not paintable, and silicone in general will not hold paint. If you need to decorate over the joint you want a hybrid polymer adhesive or a decorator's caulk.
Will it go on a sealed unit?
Silirub 2 will — Soudal have tested it against most insulating-glass edge seals and conventional PVB films. Silirub LMN will not; their sheet says it is not suitable for contact with the secondary sealant of an insulating glass unit. Soudal still recommend a compatibility test, because edge-seal systems vary between manufacturers.
Can I use it on marble or granite?
No. Both sheets say do not use on natural stone because it stains. Use a dedicated stone sealant.
How long does a cartridge last on the shelf? Unopened and stored between 5°C and 25°C, LMN is 15 months and Silirub 2 is 18 months.
Once opened, both have a limited life.
How much do I need?
Rough arithmetic rather than a Soudal figure: 300ml laid into a 5mm by 5mm joint is about 12 metres. Joint size makes a big difference though, so if you are ordering for a whole house give us a ring rather than guessing.
What is the difference between a box of 24 and a box of 15?
Nothing but the carton. Silirub LMN comes 24 cartridges to a box and Silirub 2 comes 15 — that is how Soudal pack them. Both work out 16% cheaper per tube than buying singles.
Silirub by the box
Same cartridges, same colours, same next-day dispatch — just boxed. If you have a full roofline or a run of windows on, the box is the cheaper way to buy it and it stops you running short at the wrong end of the day.
Product | Box | Per Tube | Against Singles |
|---|---|---|---|
Silirub LMN | 24 × 300ml | £4.17 | saves £19.77 — 16% cheaper |
Silirub 2 | 15 × 300ml | £8.33 | saves £24.86 — 16% cheaper |
