A balcony or terrace floor has every problem an internal floor has, plus weather. It is a finished surface that the client will judge, it is exposed to rain and sun, and anything laid loose on it will eventually blow off – possibly onto something or someone below.
Wind is the first constraint
A light cover on an exposed terrace lifts and moves, and on a high balcony it goes over the edge. That is a safety issue before it is a protection issue. Any cover on an external floor above ground level has to be fixed or weighted, and the fixing has to survive a fortnight of weather rather than a day.
Water has to go somewhere
A sealed cover over a terrace traps water against the finish and, in freezing weather, freezes and lifts. External covers need a draining detail: an embossed face down so water moves, a fall towards the drainage, and a gap at the low edge. The instinct to seal an external surface completely is the wrong one.
Sun and colour difference
External finishes fade and change with exposure. Cover part of a terrace for six months and there can be a visible difference when it comes up. On timber decking and some stone this is a real risk, and it is worth either moving the cover periodically or warning the client before handover rather than after.
Grit underfoot
External grit is harder than most finishes and a balcony is a small area that gets a lot of it. A fibrous face holds it away from the surface, but it also holds water – so on an external floor the face choice is a genuine compromise between abrasion protection and drainage, and drainage usually wins because the grit can be swept.
What to do about drainage outlets
A cover over a drainage outlet blocks it, and a blocked outlet on a terrace means standing water, which then finds its way under the cover or into the building. Cut around outlets rather than over them, and check them after any heavy rain. It is a small detail that prevents a large problem.
What is below the balcony
Anything that goes off an external edge falls, and on a balcony over a public route that is a serious incident rather than a snag. Secondary retention – tying the cover as well as weighting it – is worth the extra minute on any external floor above ground level. It is the one case where over-specifying the fixing is clearly correct.
Door thresholds onto balconies
The threshold onto a balcony is the classic trip and leak point: a step, a drainage channel, and a door that has to close over whatever is protecting it. A ramped cover that leaves the channel working and the door swinging is a specific detail rather than a general product, and it is worth measuring before ordering.
When to close the balcony instead
If nobody needs to use it, keeping the door locked for the duration is better than any cover – no wind risk, no drainage risk, no grit. Most balcony floors are damaged because the space stayed open as a smoking area or a storage spot rather than because the works required access.
A PP honeycomb panel fixed down survives the wind; light corrugated PP sheet does not and should not go on an exposed terrace at all. External behaviour in cold weather is covered in freezing weather and protection on external runs.
What we can do
We supply PP protection for external floors with a draining face and a fixing detail for exposed positions. Tell us the floor finish, the exposure and whether there is anything below, and we will say what can safely go down – including when the answer is nothing at all.