Building works for data centers.
Slabs, headroom, penetrations, compartmentation: in a data center the structure is drawn from the equipment it must carry, not the other way round.
Building and civil works for a data center - BTP, in French - cover every construction trade needed to build or convert a data center: structural and civil works, fit-out and fire compartmentation, external works and utilities, then the electrical, cooling and security packages that turn a building into a data center. What sets them apart is a reversal of the usual order: the building is sized from the equipment it must carry, power and cool. We deliver the technical packages and integrate the civil works, carried out by partner contractors, into a single chain of responsibility.
What building works a data center involves
A data center is first of all an industrial building. Before the first rack arrives it needs a slab able to carry transformers weighing tens of tonnes, clear height for cable trays and ductwork, rooms separated by fire-rated walls, plinths for chillers and generators, fuel tanks with their bunds, and roads that can take an abnormal load. All of that is construction in the strict sense: structure, civil works, fit-out, external works and utilities.
Then come the technical packages that turn the building into a data center: high-voltage to rack-level power, low-current systems for fire detection and access control, heating, ventilation and air conditioning for cooling production and distribution, and plumbing for the hydraulic networks. In construction vocabulary these are the electrical, low-current, HVAC and MEP packages. In a data center they represent most of the cost and all of the operational risk.
The boundary between the two is where projects go wrong. A penetration forgotten in a concrete wall, a plinth poured to the level shown on a superseded drawing, an opening too small for the busbar that has already been ordered: each of these gets fixed with a breaker, on a site whose programme is already pinned to the grid connection date.
How data center construction differs from an office building
Loads first. An office floor is designed for people and furniture; a transformer room or a battery room needs an order of magnitude more. Floor loading is calculated equipment by equipment, using the real weights of the selected machines, not a blanket figure per square metre.
Headroom next. Between slab and soffit you have to fit a raised floor or suspended cable trays, supply ducts, hydraulic pipework, and still leave room to work on them. A recent logistics building has that height; an office block almost never does. It is one of the first screening criteria in a retrofit.
Compartmentation last. Resilience standards require two redundant chains to be physically separated: a fire in one electrical room must not reach the other. That translates into fire-rated walls, doors and seals, distinct routes and separate openings. These requirements are drawn on the structural plans. Added afterwards, they mean rebuilding partitions inside a building that is already closed.
Phasing adds to all this. A data center is handed over in tranches, and the first tranche goes live while the next is still under construction. The building therefore has to be designed to be finished in pieces, with site separations that keep dust, noise and vibration away from rooms already in service.
How we integrate civil works with the technical packages
Civil works is not a package we carry out ourselves: we do not pour concrete. Structure, civil works and fit-out are delivered by partner civil engineering contractors, in a joint venture or as separate packages depending on how the project is organised. Our trade is the technical packages: power from the high-voltage intake to the rack, cooling production and distribution, room fit-out, security, building management, and the logistics of heavy equipment.
What we bring to that interface is the input data. The structural drawings of a data center cannot be produced without knowing what equipment they will carry: weights, footprints, penetrations, maintenance clearances, routes. Our design office in Vélizy-Villacoublay produces that data from the equipment actually selected, refurbished units included, and keeps it current until the concrete is poured. A penetration cannot be moved in a wall that has already been struck.
On site, coordination is held by the same people on both sides: whoever asked for the penetration checks it is at the right level before the pour, and whoever will install the transformer checks the plinth before delivery. That continuity is what goes missing when civil works and technical packages answer to two companies that only talk at the weekly site meeting.
In a retrofit, civil works is usually reduced to alterations: slab strengthening, new openings, new plinths, fire compartmentation. Small in volume, decisive in sequence, because until they are done no heavy equipment enters the building. They are planned from the convertibility assessment onwards.
Where this expertise applies
The data center packages this expertise covers are shown in full, the others are dimmed. Click a package for detail.
Where energy enters the site, at the interface with the public grid. It caps the available capacity: on a retrofit, what it can carry decides what the building can host.
The last line of backup, with its fuel tanks and bunding. A generator only counts once its load acceptance has been tested for real, several times - untested redundancy is a hypothesis.
Chillers and free cooling, producing the chilled water. In the French climate a large share of the year can be covered without compression - provided the loop accepts warm enough water.
The usable space: rack layout, aisle containment, cable routes and raised floors. At AI densities, room geometry matters as much as installed cooling capacity.
Physical security zones, access control, video surveillance and very early smoke detection. These are drawing-board decisions: added later, they force partition rework.
The construction packages of a data center, and who holds them
The split varies with how the project is set up. These are the packages that come up on every data center, and where we sit in each.
- Structure and civil works
- Foundations, slabs, equipment plinths, walls and steelwork, sized to the real loads of the selected equipment. Delivered by a partner civil engineering contractor, from our input data.
- Fire-rated fit-out
- Fire-rated partitions and doors, penetration seals, physical separation of redundant chains. Partner contractor, with our check of penetrations and routes before closure.
- External works and utilities
- Roads sized for abnormal loads, lifting areas, chiller and generator platforms, buried tanks and bunds, ducts and trenches for the high-voltage intake. Partner contractor, with routes defined by our access study.
- Electrical power
- Intake substation, medium-voltage switchgear, transformers, low-voltage main switchboards, UPS, generators and distribution down to the rack. Delivered by our teams.
- Low-current and security
- Very-early-warning fire detection, access control, CCTV, building management and monitoring. Delivered by our teams.
- Cooling and hydraulics
- Chillers, free cooling, chilled-water networks, air handling units, readiness for direct liquid cooling. Delivered by our teams.
- Room fit-out
- Rack layout, raised floors, cable trays, aisle containment and room compartmentation. Delivered by our teams.
- Logistics and lifting
- Access study, transport, craning and positioning of heavy equipment on its plinths. Delivered by our teams.
How civil works and technical packages sequence
Six stages. The rule running through them: no concrete is poured until the equipment it will carry is known.
Brief and equipment selection
Power budget, cooling scenarios, shortlist of new or refurbished equipment. Their weights, footprints and clearances are what will size the building.
Input data for civil works
Our design office passes loads, penetrations, openings, plinths and routes to the structural team, level by level, from the selected equipment rather than from allowances.
Cross-checked construction drawings
Structural and technical drawings are overlaid before approval: every penetration is checked against the service that will pass through it, every plinth against the equipment it will carry.
Structure and fit-out
Delivered by the civil works partner. We check penetrations before the pour and plinths before equipment arrives: an error found at this stage costs a patch, the same error found at delivery costs weeks.
Technical packages
Power, cooling, security and room fit-out, in phases if the site is handed over in tranches, with site separations protecting rooms already in service.
Testing and handover
Staged testing, transfers under load, then a single as-built file covering both the building and the installations, so the operator receives a site rather than a collection of packages.
Frequently asked questions
What do building works for a data center cover?
Every construction trade needed to build or convert a data center: structure and civil works, fire-rated fit-out, external works and utilities, then the electrical, cooling and security packages. The difference from an ordinary building is that the building is sized from the equipment it carries, powers and cools, not the other way round.
Do you provide data centers for construction companies?
No. We are not a hosting provider: we do not sell rooms or servers to construction firms. We are a contractor that delivers the technical packages of data centers and integrates the civil works they require. If you are looking for IT hosting for a construction business, that is not us.
Do you carry out the civil works yourselves?
No. Structure, civil works and fit-out are delivered by partner civil engineering contractors, in a joint venture or as separate packages depending on your set-up. What we hold is the interface: the input data civil works cannot produce on its own, the check of penetrations and plinths before the pour, and coordination on site. Our original trade is electrical installation; the rest of the chain was built around it.
Does a data center need a specialised construction company?
The civil works of a data center do not call for rare techniques: slabs, walls, steelwork are things any serious structural contractor knows how to build. What it cannot do alone is size them without knowing the equipment. The useful specialisation is therefore not in the concrete but in the input data and the coordination: that is where we come in.
How much building work does a retrofit need?
Far less than a new build, but at the most constrained moment. In a retrofit, civil works come down to alterations: slab strengthening, new openings, new plinths, fire compartmentation. Their volume is small, their sequence is critical: until they are done, no heavy equipment enters. They are therefore planned from the convertibility assessment, not when the transformers are ordered.
Who are you, exactly?
Three very different people land on these pages. Take the door that fits you.
- You areA data center operator or builderYou have works to get done, on a greenfield site or one in service: electrical, cooling, retrofit, decommissioning.Talk about works
- You areThe owner of land or a buildingAn industrial brownfield, a warehouse, a dormant grid connection: we tell you what your site can host, before you commit spend.Have a site qualified
- You areLooking for capacity in FranceAI operator, hyperscaler or enterprise: you need megawatts, a convertible site and a contractor able to deliver them. We are a contractor on 240 MW at Béthune.Talk capacity and sites