Type selection and width calculation of hotel evacuation stairs

I am fire protection expert Alexander Li. The selection of evacuation stair types and width calculations are core elements of hotel fire protection design, directly determining wh…

I am fire protection expert Alexander Li. The selection of evacuation stair types and width calculations are core elements of hotel fire protection design, directly determining whether occupants can evacuate safely and quickly during a fire. Based on my engineering experience, this is not only a basic requirement for code compliance, but also a lifeline that must be prioritized under the special scenario of high occupant density and complex evacuation paths in hotel operations. An incorrect type or insufficient width may lead to evacuation congestion, egress delays, and even stampede accidents.

Detailed Analysis

1. Selection of Evacuation Stair Types

The type of evacuation stair is primarily determined by building height, occupancy function, and fire compartmentation. According to the Code for Fire Protection Design of Buildings (GB 50016-2014, 2018 edition):

Enclosed stairwell: Applicable to multi-storey hotels (Class II high-rise public buildings with building height ≤32m). For example, in a four-star hotel project I worked on, the building height was 24m, and an enclosed stairwell was selected, separated by Class B fire doors and provided with natural smoke exhaust windows, meeting the requirements of Article 5.5.13.
Smoke-proof stairwell: Applicable to Class I high-rise hotels (building height >50m) or Class II high-rise hotels with building height >32m. For example, a five-star hotel with a height of 80m was designed with smoke-proof stairwells, with a vestibule area ≥6m² (shared vestibule ≥10m²) and a mechanical pressurization air supply system, in accordance with Article 5.5.12. Smoke-proof stairwells can effectively block smoke and ensure the safety of evacuation routes.
Outdoor evacuation stair: May serve as an auxiliary evacuation facility, but attention must be paid to its width and fire resistance rating (≥0.25h), and it shall not be used for primary evacuation. For example, a renovated hotel added an outdoor stair due to space constraints, but it served only as a backup.

Actual case: In a coastal resort hotel (height 45m), I originally designed an enclosed stairwell, but the fire review pointed out that mechanical pressurization air supply was not provided (due to limited natural smoke exhaust). It was later changed to a smoke-proof stairwell, the vestibule area was expanded to 8m², and positive-pressure air supply outlets were added, passing acceptance.

2. Evacuation Stair Width Calculation

Width calculation is based on occupant load and evacuation time. According to Article 5.5.21 of GB 50016:

Occupant density: 0.5 persons/m² (floor area) for hotel guest room areas; 1.0 person/m² for public areas (restaurants, meeting rooms). For example, for a hotel guest room area of 1000m², the occupant count is 500.
Width index per 100 persons: For buildings of fire resistance Class I and II, the required net width per 100 persons is 1.0m (above-ground floors). Calculation formula: Total width (m) = Total occupants / 100 × width index per 100 persons.
Minimum net width: Evacuation stair net width ≥1.1m (public buildings); evacuation stairs in hotel guest room areas are often 1.2m. For example, a hotel with 300 occupants per floor: calculated width = 300/100×1.0 = 3.0m, requiring 2 stairs (1.5m each).

Actual case: In a city business hotel (18 floors), I calculated 400 occupants per floor at full capacity, requiring a total width of 4.0m. Two smoke-proof stairwells were designed, each 2.2m wide (net width 2.0m), but during fire acceptance it was pointed out that the stairwell door, when opened, occupied width (door width 1.2m), resulting in insufficient effective net width. The door leaf swing was later changed to outward-opening, and the door opening width was increased to 1.5m, meeting Article 5.5.18 (door net width ≥0.9m).

3. Key Code Clauses

GB 50016 Article 5.5.12: Class I high-rise public buildings shall be provided with smoke-proof stairwells.
Article 5.5.13: Multi-storey buildings (height ≤32m) may be provided with enclosed stairwells.
Article 5.5.18: Evacuation stair net width ≥1.1m, door net width ≥0.9m.
Article 5.5.21: Calculation of width index per 100 persons.
Article 6.4.1: Combustible gas piping shall not be installed within stairwells.
GB 50261-2017 (Code for Construction and Acceptance of Automatic Sprinkler Systems), although not directly concerning stairs, emphasizes sprinkler coverage within fire compartments, indirectly affecting evacuation safety.

4. Engineering Experience and Precautions

Hotel-specific scenarios: Hotels often need to consider wheelchair users and luggage handling, so stair widths should be appropriately increased (e.g., 1.3–1.5m). In a renovation project, because the stair width was insufficient (only 1.0m), I added an outdoor stair and passed fire performance-based review.
Smoke-proof stairwell vestibule: The vestibule area must meet code requirements (public buildings ≥6m²) and shall not be occupied by pipe shafts. For example, a hotel failed acceptance because the vestibule was penetrated by a fire pipe; the pipe routing was later adjusted.
Evacuation signage: Illuminated evacuation direction signs shall be provided within stairwells (spacing ≤20m), with illuminance maintained at ≥5lx.

Summary and Conclusion: For hotel evacuation stairs, the type should preferably be a smoke-proof stairwell (Class I high-rise) or an enclosed stairwell (multi-storey); the width must be calculated based on occupant load and meet the minimum net width of 1.1m, while being appropriately increased to suit hotel operational scenarios (e.g., luggage, wheelchairs). In actual projects, I have ensured unobstructed evacuation routes through measures such as adjusting door leaf swing direction and adding vestibules.

The above are reference opinions. The actual project situation still needs to be further comprehensively evaluated and implemented in combination with specific operating conditions, site conditions, and other factors.

Engineering reference only — verify against project conditions and the latest codes.

Type selection and width calculation of hotel evacuation stairs