How to Calculate Fire Compartmentation Areas in Existing UAE Buildings

Every fire safety audit we run under the UAE Fire and Life Safety Code 2023 eventually lands on the same question: where does one fire compartment end and the next one begin, and can the building actually prove it? Detection upgrades and alarm testing get most of the attention because they are visible and easy to schedule. Compartmentation is different. It is buried in the walls, above the ceiling tiles, and inside the riser cupboards, and it is precisely the part of a gap analysis that gets skipped when a building's records only cover active systems. If your building was built before 2024 and has ever had a floor reconfigured, a shop unit converted, or a riser opened up for cabling, there is a good chance your compartmentation has drifted from what your as-built drawings claim.

What "Compartmentation Area" Actually Means Under the 2023 Code

A fire compartment is a section of a building enclosed by elements — walls, floors, doors, dampers — with a defined fire-resistance rating, built to contain a fire (and the smoke it produces) for a set number of minutes so it cannot spread beyond that boundary before occupants evacuate and the Civil Defence responds. The 2023 code sets maximum compartment floor areas by occupancy type and building height, and this is the number every gap analysis needs to start from.

For residential occupancies, the code generally caps a single compartment at 2,000 m² per floor, dropping to 1,000 m² above 45 metres, where evacuation times lengthen and fire brigade access becomes harder. Commercial and retail occupancies get more generous limits — typically up to 4,000 m² per compartment for supervised, sprinklered retail floors — reflecting the presence of automatic suppression and higher occupant awareness. Car parks and covered service areas sit in their own category again, usually capped around 2,000 m² unless open-sided ventilation reduces the smoke-logging risk. None of these figures are exotic; the calculation is simply gross internal floor area within the compartment boundary, measured wall-to-wall, with voids and shafts that penetrate the boundary treated as separate items requiring their own fire-stopping assessment. The part auditors flag most often is not the arithmetic — it's buildings where the "as-built" compartment line on the drawing no longer matches a wall that was demolished, or partially rebuilt, during a fit-out.

Mixed-Use Towers: Why Shared Risers and Ventilation Change the Calculation

The compartmentation rules get materially stricter the moment a building mixes residential floors with commercial or retail floors — which describes most towers built in Dubai Marina, Business Bay, and JLT over the last fifteen years. The 2023 code treats the transition floor between a retail podium and residential floors above as a compartment boundary in its own right, independent of the floor-by-floor limits, because the occupancy risk profile changes at that line: a kitchen fire in a ground-floor restaurant behaves very differently from a bedroom fire on floor 30, and the code does not want either to propagate into the other's stack.

Shared vertical shafts are where this gets calculated in practice rather than in principle. If a single riser carries both residential and commercial ductwork, cabling, or plumbing, every penetration through a compartment wall or floor slab into that riser needs its own fire-stopping certificate — not a blanket certificate for the riser as a whole. Auditors increasingly ask for a penetration schedule: a list of every cable tray, pipe, and duct crossing a rated boundary, cross-referenced to the fire-stopping product used and its tested rating. Buildings that were sealed with generic mastic rather than a tested fire-stop system, or that have had additional cabling pulled through after handover without re-sealing, are the single most common finding in our mixed-use audits. Ventilation is the second flashpoint: if residential extract and commercial kitchen extract share any section of ductwork or shaft, the code requires fire dampers rated to match the boundary they cross, and a mechanical smoke control strategy for the shared shaft that has been separately commissioned and tested — not assumed to be adequate because each half of the system was designed to spec independently.

Fire-Resistance Ratings for Walls, Doors, and Dampers at Compartment Boundaries

Once the compartment boundary is defined, every element that forms it needs a matching fire-resistance rating, expressed in minutes of integrity and insulation performance under standard fire test conditions. For most residential and commercial compartment walls in the UAE code, the baseline is 120 minutes for walls separating major compartments, and 240 minutes for walls enclosing protected escape stairs and lift shafts — these are the two ratings auditors check first because a failure here compromises the evacuation route itself, not just fire spread.

Doors sitting within a rated wall are typically required to carry a rating roughly half that of the surrounding wall in the older logic still referenced by many consultants, but the 2023 code is explicit rather than proportional: fire doors at compartment boundaries in residential corridors must be rated FD60 (60 minutes) as a minimum, rising to FD120 for doors onto protected stairwells in buildings above 45 metres, and every one of those doors needs a certified self-closing device, intumescent and cold-smoke seals, and a maintained certificate showing it was tested as an assembly, not just as a leaf. Fire dampers at duct penetrations through rated walls or floors need a rating equal to the boundary they cross — commonly 120 minutes at a main compartment wall — and, critically, they need an annual drop-test certificate. This is the finding we see most often in gap analyses: a damper installed correctly at handover, with no record of ever having been tested since, sitting in a ceiling void nobody has opened in a decade.

Common Retrofit Scenarios: The Converted Floor and the Shared Riser

Two scenarios account for most of the compartmentation non-conformances we log. The first is the converted floor — a floor originally designed as office space, later subdivided into serviced apartments or co-living units. The subdivision usually adds partition walls that were never assessed for fire rating, and it frequently increases the number of habitable rooms sharing a single means of escape without recalculating whether the corridor and lobby doors still meet the required rating for the new occupant load. The fix is rarely a full rebuild; it is usually a targeted upgrade of partition walls to the required rating, replacement of standard doors with certified fire door assemblies, and a revised as-built drawing lodged with the building's compliance file.

The second is the shared service riser retrofit — almost always triggered by a tenant fit-out that needed extra data cabling or a new condenser line and simply drilled through the nearest riser wall. Left unaddressed, this is a silent compartmentation failure: the wall still looks intact and the drawing still shows a 120-minute rating, but the actual fire-stopping at that specific penetration was never re-certified. The retrofit here is inexpensive relative to the risk — proper fire-stop collars or mastic systems rated to match the wall, photographed and certified per penetration — but it depends entirely on someone knowing the penetration exists, which is precisely the record-keeping gap most buildings have.

How Herman Tracks Compartmentation Certification Alongside the Rest of Your Audit Evidence

Compartmentation certification is unusual among fire safety evidence because it is inherently spatial — a rating that applies to one specific wall, one specific door, one specific penetration — rather than a single system-wide certificate like a fire alarm test log. That makes it easy to lose in a folder of PDFs and hard to reconstruct once the original installer has moved on. Herman's platform maps each compartment boundary against the building's floor plans, attaches the fire-resistance rating and test certificate to every wall, door, and damper on that boundary, and flags any penetration that lacks a matching fire-stopping certificate. When a tenant fit-out or a floor conversion happens, that change gets logged against the affected compartment automatically, so the gap analysis before your next Civil Defence audit starts from a record that already reflects what has actually been built — not what the original architectural drawing assumed a decade ago.

— The HermanWa Team