EV Charging for Multi-Storey & Underground Car Parks

Multi-storey and underground car parks are the hardest EV-charging environment to get right — and the one where a copy-paste bay layout does the most damage. Long, mixed dwell times make them a strong fit for slower AC charging, but enclosed decks bring fire, ventilation, structural-loading and limited-supply constraints that surface car parks never face. The right scheme here is duration-tiered, mostly 7kW AC on dynamic load balancing, with any DC kept to naturally ventilated entry levels — designed around the building, not bolted onto it.

Fire safety and ventilation are the first constraint, not an afterthought

In an enclosed or covered structure, fire is the design driver — everything else follows from it. The Government’s interim fire safety guidance for EV charging in covered car parks (July 2023) is the reference point: it does not ban charging underground, but it expects a competent fire risk assessment that treats the charging installation as a specific hazard, considers detection, compartmentation, ventilation and access for the fire service, and confirms that any sprinkler or suppression system remains effective. Government analysis to date indicates that where sprinklers are present and working, they are effective on EV fires.

Practical implications for a multi-storey or underground deck:

• Ventilation — mechanically ventilated basements and lower decks need the charging load and any heat considered within the existing smoke/fire strategy; do not assume the current system covers it.
• Siting — keep chargepoints away from the sole means of escape and from structural elements the fire strategy relies on; naturally ventilated upper decks are usually easier to justify than sealed basements.
• Detection and cabling — installation follows BS 7671:2018+A2:2022, including Section 722 for EV supply equipment, with cable routes chosen so a fault or fire is contained and detectable.

The honest position: fire risk assessment, not bay count, decides how many chargers your structure can safely carry. Treat it as gating work, done before you cost anything. Our feasibility quote starts here rather than with a hardware list.

Dwell time makes slow AC the right default — reserve DC for entry levels

Multi-storey and underground car parks serve long, layered dwell: commuters and office workers for a full working day, shoppers and leisure visitors for two-to-four hours, residential permit holders overnight. That duration profile is exactly what 7kW AC charging is built for — a car parked for six hours does not need 50kW, and forcing rapid charging into an enclosed deck adds heat, cost and fire complexity for no user benefit.

So the default mix is mostly 7kW AC on dynamic load balancing (DLB), which shares a fixed supply across many bays and usually avoids a DNO reinforcement. DC belongs only where the building can support it — typically the naturally ventilated entry or ground level near the barrier, offering a top-up for short-dwell visitors. Remember plain import-only chargers connect via the DNO demand-connection process (the ENA “Connecting EVs & Heat Pumps” route), not a G99 generation application.

Deck / zone	Dwell profile	Recommended kit	Notes
Upper / roof (open)	Commuter, all-day	7kW AC + DLB	Best fire and ventilation position
Mid decks	Shopper, 2–4 hrs	7kW AC + DLB	Phased, cable routes future-proofed
Ground / entry (ventilated)	Short-dwell top-up	Limited 22kW or 50kW DC	Only where structure & ventilation allow
Basement (sealed)	Overnight / permit	7kW AC only	DC generally avoided on fire grounds

Indicative installed costs as at 2026, excluding any grid upgrade: 7kW AC from ~£1,500; 22kW AC ~£3,000–£5,500 with billing; 50kW DC ~£10,000–£35,000. See the full breakdown on our cost page.

Structural loading and limited supply set the ceiling on scale

Two physical limits cap how far you can go in a decked structure. The first is structural loading and cable routing: EV charging kit, its containment and any DC unit’s weight and heat have to sit within the deck’s design loads, and cable runs have to follow existing risers and expansion joints rather than cut across them. On older multi-storeys with tight headroom and post-tensioned slabs, this alone can rule out DC on upper levels and dictate where AC upstands can be fixed.

The second is supply. A multi-storey typically has one incoming supply sized for lighting, lifts and ventilation — not for dozens of chargers at once. This is where dynamic load balancing earns its place: instead of provisioning full power to every bay, DLB shares the available headroom in real time, so a large AC estate can run off the existing connection and avoid a DNO upgrade. Where a genuine DC bank is wanted at the entry level, the DNO may still quote a customer HV substation — priced per site, and in an existing structure the physical space for one is often the real blocker, not the cost.

The sensible route is to phase: install the DLB-managed AC backbone first, lay spare containment and cable routes to future bays while decks are open, and only pursue a heavier connection once utilisation proves demand. That protects capital and keeps the fire and structural cases contained to what is actually being energised.

Standards, siting and accessibility inside an enclosed deck

Enclosed decks tighten the installation standards that a surface car park can treat loosely. Use an OZEV-authorised installer with NICEIC or NAPIT registration, working to the IET Code of Practice for EV Charging Equipment Installation, 5th Edition (2023) and BS 7671 Section 722. Where any chargepoint is publicly accessible, PAS 1899:2022 accessibility applies — screen height 800–1300mm, charging cable no longer than 7.5m — which in low-headroom or column-heavy decks constrains exactly where a unit can go.

Siting decisions that are specific to multi-storey and underground structures:

• Wall-mounted outlets suit decked layouts where floor space is tight; as permitted development the casing must stay under 0.2 cubic metres — a volume limit, not a height one.
• Keep upstands and cabling clear of vehicle swept paths, columns and the fire-service access route the risk assessment relies on.
• Position MID-certified metering and OCPP-capable hardware so back-office billing and open-data reporting work across a phased estate.

Getting siting right the first time matters more here than anywhere else, because moving a charger later means re-opening the fire and structural case. If you are weighing whether the numbers justify the extra design work, our guide on whether car-park EV charging is worth it sets out realistic utilisation and payback.

Funding fit — LEVI for public decks, private capex or a funded model for the rest

How you pay depends on who owns the deck. Council and public multi-storeys access the LEVI Fund (~£381m for English local authorities) through their local authority rather than applying directly — well suited to municipal car parks retrofitting a managed AC estate. Workplace and staff decks (an office multi-storey, a hospital or campus basement) can use the Workplace Charging Scheme: up to £500 per socket, 75% of cost, capped at 40 sockets / £20,000 across all a business’s sites, confirmed to 31 March 2027 — for off-street workplace bays only, not public parking. For state-funded education the WCS rate rises to £2,000 per socket.

For private commercial decks, the 100% First-Year Allowance on new EV charge-point equipment (extended to 31 March 2027 for Corporation Tax) is often worth more than any grant, letting you write off the full installed cost against profits in year one — take your own tax advice. See the current landscape on our grants and funding page.

On delivery model, an enclosed structure suits either route:

• Fully-funded — a chargepoint operator funds and owns the kit at £0 owner capex and you take a revenue share (often cited around 20–40%, privately negotiated). Attractive where the fire and structural work makes capex daunting.
• Owner-operated — you buy the kit and keep the retail-minus-energy spread, best where the deck already has strong, predictable dwell.

We compare both honestly, including who carries the fire and maintenance liability, on our funded vs owner-operated page. Every figure here is an indicative market range as at 2026, not a guarantee.

Frequently asked questions

Can you install rapid DC chargers in an underground or basement car park?

Usually only with caution and rarely below ground. DC units add heat and fire-load in exactly the enclosed spaces the July 2023 interim fire guidance flags, so they are normally reserved for naturally ventilated entry or ground levels, and generally avoided in sealed basements. A competent fire risk assessment, plus the deck’s structural loading and available supply, decides case by case. In most multi-storey and underground schemes the right answer is a 7kW AC estate on dynamic load balancing, with DC — if any — at the ventilated entry level only.

Does putting EV chargers in a covered car park need a new fire risk assessment?

Yes. The Government’s interim fire safety guidance for EV charging in covered car parks (July 2023) expects a competent, updated fire risk assessment that treats the charging installation as a specific hazard — covering detection, compartmentation, ventilation, fire-service access and whether existing sprinklers remain effective. It is gating work done before hardware is specified, because the assessment, not the number of bays, sets how many chargepoints your structure can safely carry. Installation then follows BS 7671 Section 722 and the IET Code of Practice, 5th Edition.

How many chargers can a multi-storey take without upgrading the electricity supply?

Often more than owners expect, because dynamic load balancing (DLB) shares one fixed supply across many 7kW AC bays in real time instead of provisioning full power to each. That commonly lets a sizeable AC estate run off the existing connection and avoid a DNO reinforcement — there has been no wider-network reinforcement charge since 1 April 2023. The real ceiling is usually the incoming supply plus structural loading and cable routing, not a flat bay count. Any genuine DC bank may still need a customer HV substation, quoted per site by the DNO.