While the idea of adding greenery to a fire escape with urban planter boxes is appealing, it is generally not allowed and strongly discouraged. Fire escapes are designated as critical safety exits, and local fire codes and building regulations almost universally prohibit obstructing them with any objects, including plants.
The primary reason is safety. Planter boxes can block the path during an emergency evacuation, creating a tripping hazard in a situation where every second counts. They can also make it difficult for firefighters to access the building or rescue occupants. Additionally, the weight of soil, plants, and water can exceed the structural load limits of many older fire escapes, posing a collapse risk.
Beyond immediate hazards, you could face fines from your local fire department or violations from your landlord or property manager for breaching your lease agreement. Moisture from watering can also lead to rust and corrosion, weakening the escape structure over time.
Instead, focus on safe alternatives for urban gardening. Consider window boxes installed securely on the interior window sill, hanging planters on sturdy walls within your balcony space (if you have one), or using indoor vertical gardens. Always prioritize safety and check your local fire codes and lease terms. When in doubt, choose a gardening method that keeps your escape route completely clear.