Carborundum Stair Insert Strip 35mm, 1m 1.5m & 2m

When a stair tread needs grip that will still be there in ten years, carborundum is the infill to specify. This is a 35mm strip of aluminium oxide grit bonded into a resin matrix, supplied in ready-cut 1m, 1.5m and 2m lengths for stairs, ramps, walkways and plant-room steps. 35mm is a broad grip band: the width to specify on deep goings, on heavily used public stairs, and where a risk assessment has asked for more contact area than a single narrow strip provides.

Why carborundum rather than a PVC insert

It does not polish out

A soft PVC or rubber insert grips well when new, then slowly burnishes under traffic until the ribs are rounded and the wet performance has quietly halved. Aluminium oxide is one of the hardest abrasives in common use; the grit wears at roughly the same rate as the resin holding it, so fresh sharp edges keep being exposed instead of being smoothed away. That is why carborundum is the default for entrance steps, industrial stairs and anywhere boots arrive wet.

It works outdoors

The resin matrix is unaffected by frost, standing water or UV, and there is no plasticiser to migrate out and leave the strip brittle. The same strip specified for an internal plant-room stair can be used on external concrete steps without a change of product.

Twelve colours, and they are not all safety yellow

Alongside obsidian, chalk and amber there are four speckled and stone-effect finishes. Where the strip has to satisfy a safety requirement without shouting, Italian marble or speckled pebble reads as part of the floor from standing height while still giving the tonal contrast a specifier is looking for.

Where it is used

Deep-going entrance steps, external concrete flights, transport and stadium stairs, fire escapes, plant rooms and workshops, and any refurbishment where a wide routed groove can be cut into stone, concrete or terrazzo.

Specifications

Choosing the right option

Width. 35mm gives a broad single band on a deep going. Drop to 20mm or 25mm where the tread is standard depth and one narrower strip will do; step up to 50mm or 55mm where the specification calls for the widest available contact area.

Length. Order the bar that covers your going in one piece; a 1.5m length cuts down to a 1200mm public-stair tread with little waste. If your treads are an awkward width, or every flight differs, order from the cut-to-size version of this insert and we will cut each piece to the millimetre.

Colour. For a safety-driven specification pick a colour that contrasts in tone with the tread rather than one that merely differs in hue: obsidian on pale concrete, chalk or Portland stone on dark stone.

Installation, use and care

Rout a groove to suit the strip, or fix to the surface where the tread cannot be cut. The substrate must be clean, dry and free of laitance. Bed the strip in an exterior-grade adhesive worked well into the groove, weight it until cured, and keep the strip at least 15mm back from the front arris so the step edge stays intact. Cutting carborundum blunts a fine-toothed blade quickly and the dust is abrasive, so cut outdoors with eye protection, or order cut to size. Clean with a stiff brush and water; do not use solvent or acid cleaners on the resin.

Frequently asked questions

Is a 35mm groove practical in an existing stone tread?

Usually yes, but check the tread thickness and any reinforcement before routing. Where cutting a wide groove is not safe, surface-bed the strip in adhesive instead.

Can I use it outside?

Yes. The resin matrix is unaffected by frost, standing water and UV, and the same strip is used internally and externally.

Does one 35mm strip replace two narrower ones?

Often, yes, and it is usually the tidier detail. Two narrow strips can be preferable where the tread is very deep and grip is wanted both at the front and further back.

What if my treads are not 1m, 1.5m or 2m?

Order the cut-to-size version linked above and specify each length between 250mm and 2000mm, tolerance plus or minus 5mm.

Ordering and delivery

Stock lengths are dispatched from inventory. Standard UK mainland delivery is a flat rate. Order one strip to check the colour against your tread before committing to a whole flight; grit colours photograph darker than they read on site.