Data centre flooring
Key takeaways
- Most of the flooring work in a data centre is invisible. The critical surface is the sealed slab underneath the raised access floor, not the panels you can see.
- That slab is a plenum. Air is drawn across it and into server intakes, so dust released from an unsealed or degrading concrete surface ends up inside the equipment.
- Flatness is a build tolerance, not a finish. A raised access floor cannot be levelled out of a slab that is outside tolerance without eating into the void.
- Static control belongs on the surfaces people work on and equipment is handled on, specified and earthed to a standard rather than described as anti-static.
- Battery, UPS, generator and fuel rooms are chemical containment jobs and they are the areas most often specified as an afterthought.
What flooring is used in a data centre?
A data centre uses a sealed resin coating on the structural slab beneath the raised access floor, static-control resin or vinyl in areas where equipment is handled, chemically resistant and bunded systems in battery and generator rooms and heavy-duty resin in loading bays and corridors. The visible raised access panels are a separate product supplied by access floor manufacturers.
That division matters when you are pricing a project. The access floor package covers pedestals, stringers and panels. The flooring package covers the slab underneath, the plant and battery rooms, the corridors and the loading areas, which together are often a larger area than the white space itself.
The slab under the raised access floor
In a traditional downflow cooling design the void under the access floor is a pressurised air plenum. Cold air travels across the structural slab before it rises through perforated panels and into the front of the racks. Anything the slab sheds travels with it.
Bare power-floated concrete dusts. It dusts more as it ages, more where trolleys and pedestals abrade it and more again where it has been cut or drilled for containment. Sealing the slab with a resin coating fixes that at source, which is why a dust-sealing epoxy is the common answer in halls built for downflow cooling, though some operators use alternative sealers or proprietary systems instead. The coating also makes the void cleanable, which matters when it has to be inspected without shutting the hall down.
Not every modern facility is built this way. Hyperscale designs increasingly cool at the slab with overhead or in-row containment and no raised floor at all, which removes the plenum argument but not the dust one, because a slab that is now the finished floor is being walked, trolleyed and worked on directly. The sealing requirement survives the change in cooling strategy even where the void does not.
Flatness is the second requirement and it is set before anyone thinks about a coating. Raised access floor pedestals are adjustable within a limited range, so a slab outside its surface regularity tolerance either eats into the void depth or leaves pedestals at the limit of their adjustment. Flatness is specified to BS 8204 surface regularity classes and where an existing slab does not meet it, subfloor preparation by grinding or a levelling screed comes before the coating.
One detail specific to this environment: electroplated steel pedestals can grow zinc whiskers over time, conductive filaments fine enough to travel in the airstream and reach live electronics. It is a known failure mode in older halls. It is a reason to keep the void clean and sealed and a reason the condition of an existing void is worth inspecting during a refurbishment survey rather than assumed.
Static control in white space and equipment areas
Static discharge is a real risk anywhere hardware is unboxed, racked, handled or repaired. The control is a floor specified as conductive or dissipative to a defined resistance range, earthed to the building and tested on installation, rather than a coating described loosely as anti-static.
The standard most operations work to is IEC 61340-5-1, which sets the requirements for protecting electrostatic-sensitive devices. The relevant point for a floor is that its performance is a system property. The resin, the conductive primer, the earthing tape and the connection to the earth point all have to be installed together and the floor is tested and certified as installed rather than accepted on a datasheet.
Anti-static and ESD flooring belongs in build rooms, staging and unboxing areas, workshops and repair benches. In the hall itself the static-control requirement is usually met by the access floor system and its earthing rather than by the slab coating, so the question at specification is which areas actually need it rather than applying it everywhere.
Battery, UPS and switch rooms
Battery rooms are the chemical exposure the rest of the building does not have. Flooded lead-acid cells carry sulphuric acid and even sealed VRLA and lithium installations are treated as a containment risk in most designs. The floor needs acid resistance, not general chemical resistance and it needs to hold a spill rather than let it reach a drain or an adjacent room.
That is a bund lining job as much as a flooring one. The system is laid continuously up the walls to form a contained area with a defined capacity, coved at the junction so there is no joint to fail and detailed at doorways with a threshold or ramp that keeps the containment closed. Where the room has a drain, it either has to be sealed or valved.
Containment in these rooms is often not a purely technical decision. Insurers and property risk engineers set their own requirements for battery and fuel areas and an FM approval or an insurer specification can dictate the bund capacity, the detailing and sometimes the system itself. Those requirements are worth obtaining in writing before a system is proposed, because they override the general design guidance and they are expensive to retrofit.
Switch rooms and UPS halls are less chemically demanding but they take heavy static point loads from the equipment itself and heavy dynamic loads when it is moved into position. The specification follows the equipment schedule rather than the room size.
Generator rooms, fuel stores and delivery areas
Standby generation brings diesel onto the site and everywhere diesel is stored, pumped or delivered needs a fuel-resistant floor with containment. Day tank rooms and bulk fuel stores are bunded. Delivery points and fill areas need a surface that survives spillage and stays slip resistant when contaminated, which is a different requirement to staying intact.
Generator halls themselves take vibration, heat and oil. The system there is normally a heavy-duty epoxy or polyurethane, thick enough to take the plant loads and detailed around the bases rather than butted up to them.
Loading bays, corridors and plant routes
Hardware arrives on pallets and moves on wheels and the route from the loading dock to the hall takes more punishment than anywhere else in the building. Loading bays take impact, dock levellers and forklift traffic. Corridors take repeated trolley loads over the same lines.
A screed-grade polyurethane or a heavy-duty epoxy handles it. The critical detail is the transition from the delivery route into the clean side of the building, where a matting or transition zone stops external dirt and grit being wheeled straight into a hall that is trying to stay particulate-free. Line marking for vehicle and pedestrian routes belongs in the same package.
Comms rooms and small server rooms
Not every server room is a data centre. A comms room in an office or a small on-premise server room in a hospital or a school has the same underlying requirements at a smaller scale: a sealed, non-dusting floor, static control where equipment is handled and a cleanable surface.
These are often the worst-specified spaces in a building because they are fitted out as ordinary rooms and then filled with equipment. Bare or painted concrete in a comms room dusts into the same air the equipment is breathing. The distinction that matters is between a decorative floor paint and an engineered resin coating: both are sold as floor paint, only one is specified to seal a slab and hold up to cleaning.
Working in a live facility
Data centres do not close. Work in an operational hall happens under a change control process, in a defined window, in a contained area with dust extraction and with agreed limits on odour, noise and hot works. Contamination control is usually written into the method statement rather than left to the contractor: negative pressure enclosures, filtered extraction, tack mats at the boundary and a particle count before the area is handed back. Cleanroom classifications do not apply to a data hall, but the procedures borrowed from that world often do. That is a bigger constraint on the flooring specification than the technical requirement.
Solvent odour is the usual sticking point. Methyl methacrylate systems cure in around two hours, which suits a short window, but the odour during application travels and is not acceptable near occupied halls without serious containment. Low-odour epoxy and polyurethane systems are often specified instead and the work is programmed around a longer cure. Where the existing slab holds moisture, an epoxy DPM is applied and overlaid as part of the same operation.
What to know before you specify data centre flooring
Separate the access floor package from the flooring package early, so the slab under the void does not fall between two trades. Specify the slab coating for dust sealing and cleanability and confirm the surface regularity tolerance before the access floor is set out rather than after.
Name the areas that genuinely need static control and specify them to the standard the operation works to with an installation test rather than a datasheet. Treat battery, UPS and fuel areas as containment first. Confirm the change control process and the acceptable working window before anyone proposes a system, because odour and cure time will eliminate options in a live hall.
Systems used in these environments are made by manufacturers such as Sika, Flowcrete, Mapei, Altro, Forbo and Gerflor and a specialist contractor matches the system to the room, the exposure and the working constraints. Listing a manufacturer here does not imply a partnership, approval or accreditation.
Budget ranges for the finishes named here sit in the commercial flooring cost guide.
Surface Specialists is a network of vetted specialist contractors covering resin systems, static-control floors, containment and subfloor preparation. Tell us the rooms, the standards and the working windows and we match the project to a contractor who works in that environment. Get in touch to arrange a site survey.
Frequently asked questions
What flooring goes under a raised access floor?
A sealed resin coating on the structural slab, normally a dust-sealing epoxy. Where the void is used as an air plenum, the slab is in the cooling airstream, so an unsealed concrete surface sheds dust that is drawn into server intakes. The coating also makes the void cleanable and inspectable.
Does Surface Specialists supply raised access floor panels?
No. Access floor panels, pedestals and stringers are supplied and installed by access floor manufacturers and their installers. The work covered here is the slab beneath the void, the plant and battery rooms, corridors, loading areas and any static-control floors elsewhere in the facility.
What is ESD flooring and where is it needed in a data centre?
An ESD or static-control floor is specified to a defined electrical resistance range, earthed to the building and tested on installation. It belongs where hardware is unboxed, built, handled or repaired: staging areas, build rooms, workshops and repair benches. In the hall itself the requirement is usually met by the earthed access floor system.
How flat does a data centre slab need to be?
Flat enough that the raised access floor pedestals sit within their adjustment range without losing void depth. Surface regularity is specified to the classes in BS 8204 and an existing slab outside tolerance is corrected by grinding or a levelling screed before any coating is applied.
What flooring does a battery or UPS room need?
An acid-resistant resin system laid as containment rather than as a plain floor, coved up the walls to a defined capacity with the doorway detailed to keep the bund closed. General chemical resistance is not the same as resistance to battery electrolyte, so the specification should name the exposure.
Can flooring be replaced in a live data centre?
Yes, under change control in a contained area with dust extraction and agreed limits on odour and noise. Odour is usually the binding constraint rather than cure time, so low-odour epoxy and polyurethane systems are often specified in place of faster methyl methacrylate where halls are occupied.
Do small comms rooms and server rooms need the same flooring?
The same principles apply at a smaller scale: a sealed, non-dusting, cleanable surface and static control where equipment is handled. Comms rooms are often the worst-specified spaces in a building because they are finished as ordinary rooms and a decorative floor paint on bare concrete is not equivalent to an engineered resin coating.