Structural silicone vs ordinary silicone: when you need which
Ordinary silicone is for sealing joints: around baths, sinks, tiles, worktops and window frames. Structural silicone is a neutral-cure sealant made for glazing and facade work, where it has to stick to glass, aluminium and stone, sit in the sun for years and carry movement. If you are sealing a bathroom or a kitchen, ordinary silicone is right and costs a fraction of the price. If you are glazing aluminium windows, sealing a curtain wall or bonding glass to a frame, use structural silicone. Where the silicone actually holds the glass in place, the joint design is the facade engineer's decision, not the shop's.
The real difference: how it cures
Many general-purpose silicones are acetoxy cure. They give off acetic acid while they cure, which is the vinegar smell. Henkel spell out the limits on their Pattex SL212: because of the acid, do not use it against lead, copper, zinc or iron, and not on mirrors or aquaria. Akfix describe their 100E as acetoxy too.
Structural silicones are neutral cure. They do not release acid, so they are safe on coated glass, aluminium, marble and concrete. KNICKER list 995 as non-corrosive to coated glass, marble, concrete and metal, but exclude copper. That is why glaziers and aluminium fabricators use them, and why a mirror or a powder-coated frame should never get an acetoxy bead.
Side by side
| Ordinary (general purpose) | Structural | |
|---|---|---|
| Cure | Often acetoxy (acid); check the pack | Neutral |
| Typical jobs | Baths, sinks, tiles, worktops, interior frames | Glazing, curtain walls, aluminium fabrication, facade and movement joints |
| Weather and UV | Varies by product | Made for long exposure outdoors |
| Pack | 280 to 300 ml cartridge, standard gun | 590 ml packs; IG STAR is a sausage needing a sausage gun |
| Price per piece | KSh 170 to KSh 500 | KSh 450 to KSh 500 |
Structural silicone prices
| Sealant | Pack | Colours | Piece | Carton |
|---|---|---|---|---|
| ABC GP Structural | 590 ml | Clear, black, grey, white | KSh 450 | KSh 8,000 |
| IG STAR Structural | 590 ml sausage | Black | KSh 450 | KSh 8,000 |
| KNICKER 995 Structural | — | White, clear, black, grey | KSh 500 | KSh 9,000 |
ABC GP Structural is made in Kenya. One 590 ml pack fills roughly 9.8 metres of a 10 × 6 mm joint, or 4.9 metres at 15 × 8 mm, before waste.
Ordinary silicone prices
| Sealant | Pack | Piece | Carton |
|---|---|---|---|
| ABC GP Fast-Curing | 280 ml | KSh 170 | KSh 3,840 |
| KNICKER GP | 280 ml | KSh 180 | KSh 3,600 |
| KNICKER High-Tech (100% silicone) | 300 ml | KSh 400 | KSh 8,400 |
| Akfix 100E (acetoxy) | 280 ml | KSh 450 | KSh 9,600 (box of 24) |
| Pattex SL212 (acetoxy) | 280 ml | Carton only | KSh 12,000 (24, KSh 500 each) |
For a fuller breakdown of what drives these prices, see silicone sealant prices in Kenya.
The middle ground: neutral weatherseal
Some jobs need a neutral cure outdoors but are not structural glazing: perimeter joints around aluminium and steel windows, door frames, cladding joints and stone. Akfix 915N is made for exactly that. Akfix describe it as a neutral-cure, low-modulus weatherseal for windows and facades, with joint widths of 10 to 35 mm. It costs KSh 950 for a 600 ml sausage, or KSh 10,800 for 12.
When structural glazing needs an engineer
In structural glazing the silicone does not just seal; it holds the glass to the frame against wind and its own weight. The bead size, the substrates, primers, adhesion tests and the cure before the glass is loaded are all part of the facade design. None of the structural silicones we stock publish a structural-glazing test approval on their product information. So for any job where the sealant carries the glass, the facade engineer or glazing contractor must specify the product and the joint, and ask the maker for their data. For weather sealing, window fabrication and movement joints, these products are what the trade in Nairobi uses every day.
Where to buy
Structural sealants are in our structural silicone collection, and the full range is under silicone sealants. Brand ranges: ABC, KNICKER and Akfix. Collect from our Nairobi trade counter at Royal Business Park, opposite Complast, Old Mombasa Road, Monday to Saturday, 8:00 to 17:30, or order for countrywide delivery at a flat KSh 350, free on orders over KSh 15,000. Contractors and resellers buying by the carton can request a trade quote on our trade page. If you are not sure which one suits your job, message us on WhatsApp with a photo of the gap or joint.
Common questions
What is the price of structural silicone in Kenya?
KSh 450 a piece for ABC GP Structural or IG STAR Structural (590 ml), and KSh 500 for KNICKER 995. Cartons are KSh 8,000 and KSh 9,000.
Can I use structural silicone in a bathroom?
You can, but you are paying for performance you do not need. A general-purpose silicone does the job for less. For which one to use room by room, see which silicone sealant to use.
Can I use ordinary silicone on a mirror?
Not an acetoxy one. Henkel rule out mirrors for Pattex SL212 because the acid it releases while curing attacks the backing. Use a neutral-cure product, or a mirror adhesive such as Akfix 900N; our guide on fixing a mirror without drilling covers it.
Do I need a special gun?
Cartridges of 280 and 300 ml fit a standard cartridge gun. Sausage packs, such as IG STAR Structural and Akfix 915N, need a sausage-type applicator gun.
Is structural silicone paintable?
None of the structural silicones we stock state that they can be painted, and Henkel state that SL212 cannot be. Where a joint will be painted indoors, use a paintable acrylic such as Akfix AS606.