Building components · Floor Build-Up
Raised Floor Pedestal
Explains the pedestal as the element that turns an uneven structural floor into a level deck, and as the entire load path of everything above it.
Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.
Overview
What a pedestal is
A pedestal is the support beneath an access floor: a base bonded or fixed to the structural floor, a column, and a head that receives the corners of the panels. Its defining feature is that it adjusts. The structural floor beneath is whatever it turned out to be; the pedestal is what converts it into a level plane at a chosen height.
It is also the whole load path of the floor above. Nothing else carries the panels, so the fixing of the base to the slab, the stability of the column, and the pedestal's resistance to being knocked while the floor is open are the properties that matter. Where the floor has to resist horizontal force the pedestals are commonly braced or the panels locked down, because a set of unconnected columns carrying loose panels is not by itself a stable arrangement.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a raised floor panel. The panel spans and is lifted; the pedestal supports and is fixed, and it stays exactly where it is while panels come and go around it.
- It is not a paving pedestal support. Those are a published material entry for carrying external paving over a waterproofed deck, where the governing concerns are drainage, wind and exposure rather than a serviced interior.
- It is not a sleeper wall. A sleeper wall is masonry carrying a suspended timber ground floor over a ventilated void; a pedestal is a discrete adjustable column carrying a demountable deck.
Terminology
Common names and aliases
These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.
- access floor pedestal
- floor jack
- pedestal support
- adjustable pedestal
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- How it is fixed to the structural floor, since the stability of the whole floor begins at that connection.
- The surface it stands on, because a base bonded to dust, laitance or a loose finish is not bonded to the slab.
- Its height and whether it is braced, since a taller pedestal is a more slender column and the floor's lateral stability comes from the arrangement rather than from any single support.
- What lands on the floor above, since partitions, heavy equipment and point loads commonly require the supports beneath them to be arranged for it.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
Every load on the access floor reaches the structural floor through the pedestals, so their arrangement, their fixing and the condition of the slab beneath them are the floor's entire load path.
The pedestal is where the level of the finished floor is set and where deviation in the slab is taken out, and that adjustment is difficult to revisit beneath a completed floor.
Pedestals are set out and fixed before the panels go down, and the floor is then walked on, loaded and opened repeatedly, which is when supports are disturbed.
Pedestals stand within the void the floor exists to serve, so they and the service routes are coordinated together or each obstructs the other.
Materials
Commonly formed from
Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.
Assemblies
Building systems this element is met in
The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.
Clarifications
Commonly misunderstood
- That the pedestals simply hold the panels up. They also establish the level of the whole floor and, in most arrangements, contribute its lateral stability.
- That the void height is a free choice made on site. It follows from what has to run through the void and from the pedestal arrangement, and changing it after the floor is laid means resetting every support.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- How are the pedestals fixed to the structural floor, and was the slab prepared for that fixing?
- What is this floor's lateral stability relying on, and is the pedestal arrangement providing it?
- Where partitions or heavy items land on the floor, is the support beneath them arranged for that?
- How do the pedestals and the services in the void coordinate with each other?
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this element involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this element comes up.
What this entry does not do
- This entry describes a position. It states no height, spacing, load capacity, fixing method or adhesive type, and none can be inferred from it.
- The stability and loading of an access floor are determined for the building by its design team; nothing here indicates what any arrangement can carry.
Floor Build-Up Elements
The deck, toppings, floating layers, isolation strips and voids that sit between a floor structure and its finish.
Browse all floor build-up entries →