C‑DRONE
Aerial view of a green mountain valley and its stream

C-DRONE GUIDE · 29 JULY 2026

Concrete multi-storey car park drone inspection: corrosion, cracks, price

A multi-storey car park looks unremarkable: a few levels of concrete slabs, ramps, white bays on grey concrete. Yet it is one of the fastest-ageing reinforced concrete structures in France, precisely because nobody ever watches it age. Unlike a roof or a façade, the driving deck of an above-ground car park is almost never waterproofed: it takes rain and frost directly, and above all the chlorides carried in by tyres from salted winter roads, which attack the reinforcement from inside the concrete, invisible until a piece of ceiling comes down. For the operator — a parking company, a landlord, a local authority, a condo trustee — the only way to know the structure's real condition is to look closely, slab by slab, column by column. A drone documents these surfaces in a few hours where a conventional inspection ties up a cherry picker and closed levels for days. Here is how a car park mission is prepared, and prices observed in 2026.

Published on 29 July 2026, reviewed on 29 August 2026 — regulations in force as of August 2026.

A concrete structure that ages faster than it looks

An above-ground reinforced-concrete car park suffers a combination of attacks few other structures cumulate: freeze-thaw cycles on exposed levels, progressive carbonation of the concrete in contact with air, and above all chlorides dropped by tyres that have driven on salted roads — the same mechanism that eats away at road bridge decks. Once chlorides reach the reinforcement, corrosion starts: the steel rusts, expands, and bursts the cover concrete from the inside — a process that stays invisible at the surface for years before a piece spalls off.

Unlike a flat roof, the driving deck of an above-ground car park is almost never fully waterproofed: it is designed to take rain and run-off directly, which speeds up the penetration of aggressive agents towards the underside of the level below — ceilings, beams, column heads — where defects show up first.

Cracks, spalling, visible corrosion: what the drone documents

The mission runs like close-range photogrammetry: the drone flies over every open level and positions itself under the ceilings of covered levels to photograph in high resolution the undersides of slabs, beams, prestressing anchorages and column heads. The images reveal what a ground-based visual check, hampered by headroom and artificial lighting, often misses: cracks tracing along the reinforcement, spalling with exposed steel, rust streaks typical of active corrosion, surface crazing, degraded expansion joints. Each defect is geolocated on a level plan, following exactly the method we detail for concrete retaining walls, another structure where reinforcement corrosion shows at the surface first.

Research is moving fast on contactless corrosion detection: a team at ETH Zurich led by Pascal Pfändler, Ueli Angst and their co-authors developed and validated, in a study published in 2024 in Automation in Construction, a flying robot able to measure the corrosion potential of reinforcement through direct contact, alongside conventional visual inspection (see the study on Google Scholar). On routine missions the service stays photographic: it is what directs the structural engineer's probes and core samples, without waiting for corrosion to become visible to the naked eye.

Under the slab and on buried levels: flying without GPS between the columns

A multi-storey car park rarely offers a single type of space: open-air levels, exposed to the outside through wide structural bays, are flown line-of-sight like any outdoor structure; covered or underground levels, by contrast, deprive the drone of satellite signal between the beams and columns. Navigation then relies on the aircraft's visual and proximity sensors rather than GPS, following the same logic we detail in our tunnels and underground galleries guide: a pre-planned flight path, headroom measured in advance, a slow and stabilised flight between parking bays.

On the airspace side, a multi-storey car park almost always sits within a built-up area: open levels fall under the specific-category scenarios described in our flying in cities guide, with prior declaration to the préfecture where required; fully enclosed levels are mostly negotiated with the operator: mechanical ventilation switched off for the flight, users informed, a slot during quiet hours to limit the number of moving vehicles.

Who commissions this audit, and when

Large car park operators — public-service concession holders, commercial property companies, airport and shopping-centre managers — schedule these campaigns as routine, every three to five years, to feed their multi-year major-maintenance plan and prioritise waterproofing or reinforcement repair works before a defect turns into an incident. Condo trustees follow the same logic on a single structure, often alongside the now-mandatory multi-year works plan.

Two other moments naturally trigger the mission: the handover of a new or recently renovated car park, where the photographic survey freezes the baseline condition before the completion-warranty period expires — on the same principle as our construction works acceptance guide — and the acquisition of a property asset including a multi-storey car park, where the structural audit feeds into the technical due diligence file handed to the buyer, with costed works expected over the next five to ten years.

Prices observed in 2026

Ranges observed in 2026 (excl. VAT):

The extra cost of a drone campaign stays well below that of a cherry picker mobilised level by level over several days, closed bays included. Our surveying and photogrammetry page presents the service; request a quote stating the number of levels, total area and the access available to covered levels.

Request a free quote

Also worth reading