External steps and fire escape stairs are the two cases where the usual answer is wrong. Water and grit change the requirement on the one hand, and fire regulations change it on the other. Getting either wrong is not a snagging issue, it is a safety issue.
External steps: water is the whole problem
An external flight collects whatever falls on it, and unlike a flat external area it holds it at each nosing. A sealed cover over an external step traps water against the surface and, in freezing conditions, the trapped water expands and lifts the cover – by which point it is a slip hazard rather than protection. Any external stair cover has to drain, which usually means an embossed face down and a gap at the front edge rather than a sealed wrap.
Grit and salt are harder than the step
External grit, and de-icing salt in particular, is harder than most step finishes and gets ground in by every footfall. Covers on external steps wear several times faster than the same cover indoors, and expecting indoor cover life on an external flight is the most common budgeting error here. Plan on replacing them, not on reusing them.
Fire escape stairs: check before covering anything
A fire escape is a protected route and there are usually rules about what can be put on it – combustible materials, anything that reduces the effective width, anything that could slip. Before specifying anything for a fire escape, check with the responsible person for the building and get it in writing. This is not a case where a sensible product choice is enough; it needs agreeing.
What usually is allowed
In practice, what tends to be acceptable on a fire escape is a mechanically fixed, non-combustible or appropriately rated cover that does not reduce the going and does not create a trip edge – and often nothing at all. The alternative that is almost always acceptable is protecting the flight by routing the works traffic elsewhere and leaving the escape stair untouched. That is usually the answer worth pursuing first.
Where external protection is genuinely needed
On a new external flight that is finished and then has to survive the rest of the build. On stone or tile steps being laid before the landscaping is done. And on steps that are the only access, where closing them is not an option. In all three, drainage and fixing matter more than the wearing surface.
Ice, and why grit is the answer
On an external stair in freezing weather, the safest intervention is usually grit rather than a better cover: no cover surface stays grippy under ice, and a cover that has frozen to the step cannot be lifted or cleaned. Grit the flight, keep it swept, and accept that the cover is doing impact protection rather than slip protection until the weather turns.
Galvanised and steel steps
Metal external steps are usually galvanised or painted steel, and a cover that holds water against them defeats the coating and starts rust at exactly the point where it is hardest to treat. Drainage matters more here than on concrete. Where steel steps are being protected, the cover has to keep air moving rather than keep water out.
What survives out there is a PP honeycomb panel with a draining face, fixed down rather than laid; corrugated PP sheet will lift in the first wind and should not be used on an exposed flight. Grip on external steps is discussed in anti-slip protection for temporary steps and stairs.
What we can do
We supply PP stair covers cut to size with a draining detail for external use, and we will ask about the fire strategy before quoting anything for an escape route. Tell us where the flight is, what it is made of and whether it is a protected route, and we will say plainly whether we can help or whether the flight should be left alone.