Fire Escape Calculations and Why Door Width Matters
How Many People Can Exit Through a Door?
When designing buildings for safety, exit capacity is one of the most important factors. The width of a door directly affects how many occupants can safely evacuate a building during an emergency.
In the UK, evacuation design typically follows guidance derived from Approved Document B, where exit widths are calculated using a simple rule:
1 person requires approximately 2.85 mm of clear exit width.
This allows designers to quickly determine how many people a doorway can safely serve during an evacuation.
For example:
| Door Clear Width | Occupants Served (Approx.) |
|---|---|
| 800mm | 280 people |
| 900mm | 315 people |
| 1000mm | 350 people |
| 1200mm | 420 people |
| 1500mm | 525 people |
These figures assume a clear, unobstructed door opening and are commonly used during fire risk assessments, building design, and occupancy planning.
However, in modern buildings—particularly offices, schools, hospitals and apartments—doors are required to do much more than simply provide an exit.
They must also provide fire protection and acoustic performance.
Fire Safety and Acoustic Performance in One Doorset
Escape doors are often located in corridors, stairwells, plant rooms, meeting rooms and residential entrances—areas where noise control and fire protection are equally critical.
This is where SilentDoor Rw® acoustic fire doorsets are designed to perform.
SilentDoor Rw® combines high acoustic ratings with certified fire resistance, ensuring that buildings remain safe, compliant and comfortable.
Typical performance options include:
| SilentDoor Model | Acoustic Rating | Fire Rating |
|---|---|---|
| SilentDoor Rw® 40T | 40dB | Up To FD90 |
| SilentDoor Rw® 45T | 45dB | Up To FD90 |
| SilentDoor Rw® 50T | 50dB | Up To FD90 |
| SilentDoor Rw® 55T | 55dB | Up To FD60 |
These doorsets are ideal where sound containment and fire compartmentation must work together.
Typical Applications
SilentDoor Rw® acoustic fire doors are commonly specified in:
Apartments and residential developments
- Entrance doors
- Corridor doors
- Plant room access
Commercial offices
- Meeting rooms
- Boardrooms
- Recording spaces
- Equipment rooms
Education and healthcare
- Lecture theatres
- Music rooms
- Consultation rooms
- Hospital corridors
In these environments, a door must control noise, maintain fire integrity, and still allow safe evacuation capacity.
Example: Fire Exit Capacity with Acoustic Doors
Consider a 1000 mm clear opening door used as part of an escape route.
Using the 2.85 mm per person rule:
1000 mm ÷ 2.85 mm = approximately 350 occupants served
Specifying a SilentDoor Rw® 45T FD60 acoustic fire doorset ensures that the same doorway:
- Provides FD60 fire resistance
- Achieves Rw 45 dB acoustic insulation
- Maintains the required evacuation capacity
This means the building remains safe, compliant, and acoustically comfortable.
Why Door Quality Matters in Escape Routes
Not all doorsets are designed for demanding environments. Poorly specified doors can lead to:
- Sound leakage between rooms
- Reduced fire resistance
- Premature wear in high-traffic areas
- Compliance issues during inspections
SilentDoor Rw® doorsets are engineered to provide:
- High acoustic insulation
- Certified fire ratings
- Robust construction for commercial use
- Bespoke sizes and finishes
This makes them suitable for both standard door openings and large custom configurations.
Bespoke Sizes for Modern Buildings
Every project is different. SilentDoor Rw® doorsets can be manufactured in a wide range of sizes to suit building layouts.
Typical configurations include:
| Configuration | Example Size | Application |
|---|---|---|
| Single Door | 900 * 2100mm | Offices / apartments |
| Single Door | 1000 * 2100mm | Escape routes |
| Double Door | 1600*2100mm | Assembly areas |
| Double Door | 2000*2100mm | Plant rooms / halls |
Larger openings allow greater occupant flow, while acoustic cores maintain high sound insulation.
Choosing the Right Door for Safety and Performance
When specifying doors for modern buildings, it’s important to consider:
- Fire rating
- Acoustic performance
- Door width and evacuation capacity
- Durability in high-traffic environments
SilentDoor Rw® doorsets are designed to meet all of these requirements in a single certified system.
SilentDoor Rw® – Engineered for Quiet and Safety
Whether you’re designing apartments, offices, schools or healthcare facilities, SilentDoor Rw® provides the performance needed for both fire safety and acoustic control.
If you need guidance selecting the correct acoustic fire doorset for your project, the SilentDoor team can help specify the right configuration.
Contact us today to discuss your project requirements.
