Documento Básico SI Seguridad en caso de incendio – Fire Safety in Buildings (DB-SI) Spain
The Documento Básico SI Seguridad en caso de incendio (DB-SI) is the primary regulatory instrument for fire safety in building projects across Spain. Issued by the Ministerio de Transportes, Movilidad y Agenda Urbana (formerly known as the Ministerio de Fomento), this technical code forms an integral part of the Código Técnico de la Edificación (CTE). This specific edition is the consolidated version from December 20, 2019, which includes official ministerial commentaries and clarifications updated through December 22, 2022. It provides the legal and technical requirements necessary to satisfy the basic safety requirement for reducing fire risk to acceptable limits for occupants.
The regulatory scope of the DB-SI covers six fundamental areas: interior fire propagation, exterior propagation through facades and roofs, occupant evacuation, fire protection installations, fire service intervention access, and structural fire resistance. It applies to most building types, with the notable exception of industrial premises, which are governed by the Reglamento de seguridad contra incendios en los establecimientos industriales (RSCIEI). The document defines critical parameters such as fire sectorization limits, evacuation path lengths, and the required fire resistance (R, REI, and EI ratings) for structural and partitioning elements.
The following sections detail the technical standards for compartmentation, evacuation procedures, and the protection of structural integrity, incorporating requirements from various UNE-EN standards cited throughout the code.
Interior Fire Propagation and Compartmentation
Section SI 1 Propagación interior establishes the rules for dividing buildings into sectores de incendio (fire sectors) to limit the spread of fire. The maximum constructed area for a fire sector is generally set at 2,500 m², though this may vary by building use.
- Residencial Vivienda: Fire sectors must not exceed 2,500 m², and elements separating individual dwellings must have a minimum fire resistance of EI 60.
- Docente: Buildings with more than one floor are limited to 4,000 m² per sector.
- Locales de riesgo especial: Specific areas such as storage rooms, kitchens (over 20 kW), and laundry rooms are classified as low, medium, or high risk based on volume or power, requiring specific partitioning from EI 90 to EI 180.
- Sectores de riesgo mínimo: These sectors, used primarily for circulation, have no maximum area limit but must maintain strict fire load density below 40 MJ/m².
Exterior Propagation: Facades and Roofs
Section SI 2 Propagación exterior regulates the vertical and horizontal spread of fire between buildings or different fire sectors within the same structure via the envelope.
- Medianerías y fachadas: Vertical separation elements between different buildings must be at least EI 120.
- Horizontal separation: Facade points that are not EI 60 must maintain a minimum horizontal distance ranging from 0.50 m to 3.00 m depending on the angle between the facade planes.
- Vertical separation: To limit vertical spread between sectors, a facade strip of at least 1.00 m in height must have an EI 60 rating.
- Cubiertas: Roofs must have a minimum fire resistance of REI 60 in a 1.00 m strip where they meet fire-rated partitioning walls.
Occupant Evacuation Requirements
Section SI 3 Evacuación de ocupantes details the calculation of occupancy and the design of evacuation routes to ensure a safe exit to an espacio exterior seguro (safe exterior space).
- Cálculo de la ocupación: Densities are assigned by use, such as 20 m²/person for residential areas and 1.5 m²/person for standard classrooms.
- Recorridos de evacuación: Evacuation path lengths are generally limited to 25 m when only one exit is available, or up to 50 m in specific low-occupancy or outdoor scenarios.
- Escaleras protegidas: Protected stairs must be enclosed in EI 120 elements and accessed via doors with EI2 60-C5 ratings.
- Accessible evacuation: Buildings must provide zonas de refugio (refuge areas) for persons with disabilities, with specific dimensions of 1.20 x 0.80 m per wheelchair user.
Structural Fire Resistance
Section SI 6 Resistencia al fuego de la estructura defines the required duration that a structural element must maintain its load-bearing capacity (R) during a fire, based on the building height and use.
- Residencial Vivienda: Structural resistance is R 60 for buildings up to 15 m, R 90 up to 28 m, and R 120 for heights exceeding 28 m.
- Commercial and Hospital: Higher requirements apply, reaching up to R 180 for buildings over 28 m in height.
- Parking structures: Generally require R 90 structural resistance if they are below other uses or serve as independent structures.
- Secondary elements: Elements whose collapse does not compromise global stability or evacuation (e.g., small mezzanines) may be exempt from fire resistance requirements.
Frequently Asked Questions
What is the maximum constructed area for a fire sector in a residential building?
According to Table 1.1 in Section SI 1, the constructed area of a fire sector in a residential building must not exceed 2,500 m².
At what power level does a kitchen become a 'special risk' area?
A kitchen is classified as a low-risk special area if its installed power is between 20 kW and 30 kW, medium-risk up to 50 kW, and high-risk if it exceeds 50 kW.
What are the dimensions for a fire-fighting emergency lift?
An ascensor de emergencia must have a minimum load capacity of 630 kg, cabin dimensions of 1.10 m x 1.40 m, and a travel speed capable of completing the full height in under 60 seconds.
What is the required fire resistance for structural elements in a residential building over 28 meters high?
For buildings with an evacuation height exceeding 28 meters, the structural elements must provide a fire resistance of at least R 120.
When is a 'vestíbulo de independencia' required for a lift?
A vestíbulo de independencia is mandatory at lift entrances in high-risk areas or parking zones, and when lifts connect different fire sectors, unless the lift doors are already protected within a fire-rated stairwell.
What is the maximum evacuation distance for a parking lot with a single exit?
In parking uses (Uso Aparcamiento), the maximum evacuation distance to a floor exit is 35 meters if there is only one exit.
