Underground car park cleaning: removing road salt, oil stains and tyre marks properly

Underground car parks are often only noticed when it is too late: when spalling appears in the concrete, rust streaks run down the columns or the property manager has an expensive refurbishment quote on the desk. Yet regular underground car park cleaning is the cheapest form of prevention. In this guide we explain why road salt is so dangerous for car parks, how a professional clean works, how often it is needed and what costs you can expect in Vienna, Graz, Linz and Salzburg.

What is underground car park cleaning?

Underground car park cleaning covers the driving lanes, parking bays, ramps, walkways, drainage channels, stairwells and ancillary rooms of an underground or communal garage. Depending on the scope, professionals distinguish between:

• Dry cleaning: machine sweeping with a sweeper-vacuum to remove sand, grit, leaves and dust.
• Wet cleaning: cleaning with a scrubber-dryer, which applies water and detergent, scrubs the floor and immediately picks up the dirty water again.
• Intensive or deep cleaning: additional treatment of oil and tyre marks, cleaning of channels and silt traps, walls and columns in the splash zone, signage and light fittings.

Why does an underground car park need cleaning?

1. Road salt attacks concrete and reinforcement

In winter, every vehicle brings considerable amounts of chloride into the car park with its slush and salty water. The salt water penetrates cracks and porous areas in the concrete. Once the chlorides reach the steel reinforcement, it starts to corrode. Rust takes up more volume than steel, the concrete spalls and the load-bearing capacity can suffer. Experts call this chloride-induced corrosion – one of the main reasons for expensive car park refurbishments. Removing the salt thoroughly after winter considerably reduces the time it has to do damage.

2. Slip hazards and liability

Oil films, tyre rubber, wet dirt and leaves make ramps and walkways slippery. Under certain circumstances, the owner or operator is liable for accidents in communal areas. Documented, regular cleaning is therefore also part of the duty to keep the premises safe.

3. Environmental protection

Oil, brake dust and tyre rubber do not belong in the sewer system. Professional scrubber-dryers pick up the dirty water; where oil separators are installed, they must be serviced regularly. Oil must never be hosed into the channels with a pressure washer.

4. A sense of security and preserving value

A bright, clean car park with legible signs and clear floor markings feels safer. For residents, customers and staff, it is the first and last impression of the building.

How often should an underground car park be cleaned?

The most important date is the spring clean after the gritting season, typically March to April. A second clean in autumn removes leaves and dust before the next salt season begins.

Usage matters as much as size. A car park with a car-sharing pool, delivery vans or a shop entrance sees far more movements per day than a residential garage where most cars stay parked for the week. Long ramps from street level also bring in more water and grit, because every vehicle carries what it picked up outside straight down to the lower decks.

How is an underground car park cleaned professionally?

The same rules apply here: top to bottom and clean to dirty. In multi-storey car parks you start on the top deck and work down to the lowest level, so that dirty water does not run down the ramps onto areas you have already cleaned. Within each deck you work towards the drainage channels.

1. Notice: residents or users are informed in good time by a notice. Parking bays are kept clear section by section; vehicles that are not moved are worked around.
2. Cordon off and secure: work areas are marked and ramps temporarily closed if necessary.
3. Dry pre-clean: a sweeper-vacuum for sand, grit and leaves, plus manual work in corners, around columns and under pipes.
4. Stain treatment: oil and fuel stains are pre-treated with a suitable alkaline cleaner or oil absorbent, allowing enough contact time. The absorbed oil is collected and disposed of properly.
5. Machine wet cleaning: a scrubber-dryer with suitable brushes or pads. On coated floors (epoxy, polyurethane), only suitable pads and cleaners are used so the coating is not damaged.
6. Ramps and walkways: manual follow-up cleaning, especially along edges and in grooves.
7. Channels and drains: lift the gratings, clear out the channels and check the silt traps.
8. Walls, columns, signs: wash the splash zone up to about one metre high and clean the signage.
9. Handover and documentation: a walk-round, photo documentation and notes on any damage spotted, such as spalling or rust marks.

In underground car parks, professionals use pressure washers only selectively. Hosing down large areas forces water and salt into cracks and joints – exactly where it does the most damage.

Coated or uncoated floor?

Many newer car parks have a protective surface coating of epoxy or polyurethane resin, designed to stop salt water from penetrating the concrete. These coatings are tough but not indestructible: brushes that are too hard, cleaners with a high solvent content and sharp grit ground in under tyres all wear them down. On coated floors we therefore use soft pads and neutral to mildly alkaline cleaners. Uncoated concrete can take stiffer brushes but soaks up oil and salt water like a sponge – which makes regular cleaning all the more important.

A simple test: if water forms droplets on the floor and beads off, the surface is still sealed. If it soaks in immediately and leaves dark patches, the concrete is open – a sign that it is time to talk to the property manager or a building surveyor about a protective coating.

A worked example

A typical Viennese residential car park with 40 spaces covers around 1,200 square metres including the driving lanes. Depending on obstacles and how dirty it is, a scrubber-dryer manages roughly 600 to 1,000 square metres per hour of pure machine time. On top of that come the pre-sweep, stain treatment, manual work on columns and channels, and the ramps. For a car park like this, a realistic estimate is two people working for half a day to a full day. The more cars are moved out of the way, the faster and more thorough the job.

Documentation for the property manager

Before-and-after photos help the property manager justify the operating costs to residents and reveal damage early: spalling, rust streaks, damp patches on the ceiling or broken channel gratings. These observations are often worth more than the cleaning itself, because they allow a small repair to be made before major refurbishment becomes necessary.

Preparing residents and users

How well a car park can be cleaned depends to a large extent on how many spaces are empty on the day. A clear notice at the entrance and by the lifts, put up at least a week in advance, should state the date, the time window and which sections will be cleaned when. Where possible, the cleaning is split so that each resident only has to move their car once. In larger complexes, a reminder a day or two beforehand noticeably increases the number of free spaces.

Fee from Bling Bling: My professional tip for property managers: book the wet clean for March or April every year as a fixed date – before the first resident even asks. Salt that is removed early can no longer damage the concrete.

You make the mess – we make it go away

How much does underground car park cleaning cost? Price guidelines for 2026

Billing is usually per square metre of car park area or as a flat fee per job. The following guideline prices are net, plus VAT. The price depends on the area, how dirty it is, the number of levels, the floor surface and how many vehicles remain parked during the clean.

In residential buildings, the costs are usually charged through the operating costs, provided the tenancy agreement or the owners’ agreement allows for this. Find out more about our service on our garage cleaning in Vienna and car park cleaning in Vienna pages. For winter conditions outside the entrance, our winter gritting service in Vienna has you covered.

How working with us works

We agree the date with the property manager or operator, provide the notice for users on request and, if needed, work section by section or overnight so the car park remains usable. Our customers rate us 4,8 stars on Google from 200 reviews.

Common underground car park cleaning mistakes

• Cleaning only in autumn: the salt then sits in the concrete all summer. The most important clean is the one in spring.
• Pressure-washing large areas: water and chlorides are forced into cracks, and dirty water ends up unfiltered in the sewer.
• Flushing oil into the channel: an environmental problem and a burden on the oil separator.
• Aggressive cleaners on coatings: epoxy and PU coatings become dull and rough and lose their protective effect.
• No advance notice: if every car stays put, only a fraction of the floor gets cleaned.
• Forgetting the channels: blocked drains lead to puddles in which salt water stands for a long time.
• Not reporting damage: spalling and rust marks should be shown to a specialist early – the sooner, the cheaper the repair.

Underground car park cleaning checklist

• Date set after the gritting season (March/April)
• Notice put up at least one week in advance
• Section plan for parking bays drawn up
• Dry cleaning with sweeper-vacuum
• Oil and fuel stains pre-treated
• Wet cleaning with scrubber-dryer, top deck first
• Ramps, walkways and edges cleaned again by hand
• Channels, gratings and silt traps emptied
• Walls and columns cleaned in the splash zone
• Signs and markings clean and legible
• Photo documentation and damage report sent to the property manager
• Autumn date for leaves and dust scheduled

Frequently asked questions