Terrace & Patio Cleaning in Geneva

Paving, wood, composite, exposed aggregate: each surface has its method

This is what separates a successful terrace clean from a ruined surface, and it is the first question worth asking any provider. Method is not chosen according to the equipment available but according to what is actually on the ground.

Concrete slabs, interlocking pavers and hard stone such as granite take high pressure and mechanical brushing. That is the straightforward case. Soft stone — molasse, soft limestone, some sandstones — does the opposite: under strong pressure the grain lifts away, the surface turns rough and then holds dirt twice as fast. The damage is not visible on the day; it shows up the following season.

Wood calls for inverted logic. Larch, treated pine or hardwood decking has to be brushed along the grain, at low pressure, with a suitable product. A high-pressure jet erodes the soft wood between the grain lines: the board goes furry, greys faster and eventually splits. Composite is more forgiving but it scratches, and a chlorinated product can bleach it unevenly — a pale patch on grey composite cannot be recovered.

Exposed aggregate and washed concrete are a category of their own: their surface is deliberately rough, so it holds dirt and moss in its hollows. They take longer than smooth paving of the same area, which is why a serious quote asks for a photo or a visit before committing.

High pressure: why it often damages more than it cleans

Pressure washing has a reputation for effectiveness that comes from an immediate visual effect: the dirt leaves before your eyes. The problem is what it takes with it, and that only becomes apparent later.

On paving jointed with polymeric sand or mortar, a powerful jet scours the joints out. The sand goes, water gets in, slabs work loose, and the following season moss returns faster because it now has hollows to settle into. Re-jointing costs far more than the cleaning ever did.

On wood, as described above, high pressure erodes the soft material between the grain lines. On soft stone it strips the grain. On outdoor tiling it can blow out an expansion joint. And on an upper-floor balcony it throws soiled water onto the neighbour below and behind the façade — a thoroughly concrete source of neighbour disputes.

We treat pressure as a setting, not a selling point: high on concrete and interlocking pavers, moderate on jointed hard stone, low with brushing on wood and soft stone. When a surface is too degraded to be cleaned without risk we say so, rather than hosing it down and letting the result speak for us.

Moss, algae and lichen: where they come from and why they return

This is not about dirt but about moisture and light. Moss establishes itself where the surface stays damp and gets little direct sun: the north side, under a tree, in the shade of a wall, in a poorly ventilated corner. That is why a terrace can be spotless across two thirds of its area and green on the last third.

Brushing alone removes the visible growth but not the spores lodged in the porosity of the surface, which is why it comes back quickly. An anti-moss treatment applied after cleaning acts on what remains and markedly slows the return. It is worth being honest about duration, though: depending on exposure, that means one season to two years, not a permanent fix.

Lichen is more stubborn. It anchors into the material and can leave a shadow even after removal, particularly on porous stone. It is treated chemically then lifted mechanically, over several passes if needed, and a residual mark is possible — we flag that beforehand.

Three maintenance habits genuinely change how often work is needed and they cost nothing: clear fallen leaves before winter rather than in spring, because a mat of wet leaves is exactly the environment moss needs; check that water drains away and does not pool in a hollow; and cut back whatever keeps an area permanently shaded.

Grease stains: barbecue, oil and pine resin

A grease stain is not treated like surface soiling because it has penetrated the material. That is the reason for the 1.4 factor: working time doubles compared with straightforward washing.

Barbecue stains are the most common and the most often mishandled. Hot fat penetrates deep into porous paving; once cold it is set. An alkaline degreaser with dwell time, sometimes repeated, lifts most of it. On very porous stone a shadow can remain — worth knowing before hoping for an as-new finish.

Engine and hydraulic oil, common on a garage approach or a parking space in front of the house, are treated with a powder absorbent first and never with water first: water spreads the stain instead of removing it. Pine resin is a seasonal issue familiar to wooded properties in the Geneva countryside; it needs a solvent matched to the surface and a good deal of patience, because it hardens into a crust.

Wine, fruit dropped from a tree and bird droppings belong to another family: they are tannic or acidic, and on limestone they may have slightly etched the surface. Cleaning removes the colour but not the micro-corrosion. Here too, saying so in advance is better than leaving the impression of a rushed job.

Railings, balustrades and balcony glazing

On a balcony it is often the railing rather than the floor that creates the impression of dirt, because it sits at eye level. It is also the item most often left out of quotes.

A glass balustrade accumulates a grey film of urban dust and mineral deposit from successive rainfall. It is treated like glazing: degreased then rinsed with demineralised water, otherwise the lime in Geneva mains water leaves a haze as it dries. Painted metal railings need a neutral product: a degreaser that is too alkaline dulls the paint. Stainless steel shows fingerprints and water spotting and is finished dry.

The technical point we always check is the fixing. On an older balcony, a balustrade set into carbonated concrete may have a corroded anchor. We never lean on a balustrade while working, and we report any abnormal movement to the owner or the managing agent — that is a safety matter, not a cleaning one.

Blind housings and the tracks of French doors opening onto the terrace are included in our work, because they collect exactly the same dust and because they get looked at during a check-out inspection.

When to clean a terrace, and how often?

The best moment is late winter or early spring, before first use. The reasons are practical: moss has reached its peak after the damp months, it lifts more easily while still alive and saturated, and an anti-moss treatment applied then protects the whole season you are going to use the terrace.

A second pass in autumn makes sense on terraces under trees, and it helps more than it appears: removing fallen leaves before winter prevents the damp mat that feeds moss. It is a lighter and therefore cheaper clean, and it reduces the following spring's work.

As a routine, once a year is enough for a sunny, well-ventilated terrace. Move to twice a year if it faces north, sits under trees or along a hedge, or if you cook outdoors regularly. Exposure to the lake adds a mineral deposit that shows on glazing more than on the floor.

We avoid two conditions. Frost, because water that has worked into a joint or a hairline crack freezes and breaks the material apart. And full summer heat on a dark surface, where the product dries before it can act and leaves marks — in that case we work early in the morning.

Terrace and check-out inspection: what the managing agent looks at

A terrace or balcony is part of the property and it is inspected at handover. Tenants regularly underestimate this item, even though it can be assessed in thirty seconds and photographed easily by a régie — the managing agent acting for the landlord.

Three things get looked at: floor cleanliness, the state of the railings and water drainage. A terrace green with moss, a railing coated in grey film or a drain blocked with leaves are cleanliness reservations, withheld from your rental deposit at whatever rate the agent chooses.

The usual distinction applies here too: normal wear is not your responsibility, damage is. Paving that has weathered over eight years of exposure is depreciation. A barbecue stain, a slab cracked by an over-heavy planter or composite bleached by an unsuitable product are damage. That is precisely why we refuse to use chlorinated products on composite: the pale patch it leaves turns a clean into a liability.

When a property we handle at end of tenancy has a terrace or balcony, we quote it in the same document. It is a separate line because it means different equipment and additional time, but it is stated up front rather than discovered at handover.

Doing it yourself or delegating?

For a 6 to 10 m² balcony in paving, doing it yourself is perfectly reasonable: a stiff long-handled brush, water, a suitable product and an hour of work. The result can be excellent and you do not need us.

Three situations change the calculation. The surface first: as soon as there is wood, soft stone, composite or exposed aggregate, a mistake in method costs more than the job — and it cannot be undone. Area second: beyond 40 or 50 m² this is half a day of physical work on your knees, and hiring a machine does not remove the need to brush. Stains third: ingrained grease or lichen need products you would not buy for once-a-year use.

A word on hired pressure washers, because this is the most common false economy on this job. They are very effective on concrete and destructive on almost everything else, and the damage — scoured joints, furry timber, crumbling stone — only appears the following season, when it is too late to connect cause and effect.

So our position is simple: small paved balcony, do it yourself. Wood, soft stone, composite, large area, ingrained stains or a check-out inspection at stake: have us come.

Which method suits which surface

On an upper-floor balcony we control run-off so that no soiled water reaches the neighbour below or the back of the façade. When a surface is too degraded to clean without risk, we say so in the quote.