Core Design Rules (UK Standards)

Lift/Elevator Requirements (UK)

• Provision of Lifts: In residential buildings of three or more storeys, at least one passenger lift should be provided to ensure step-free access for all users (as per Approved Document M guidance). Buildings two storeys or less (ground + one floor) typically do not require a lift under accessibility standards for dwellings.
• Number of Lifts: Provide a minimum of two lifts if the building contains 30 or more flats above ground floor or exceeds about 6 storeys, whichever condition is met first^[1]. This is to ensure redundancy – if one lift is out of service, residents still have access.
  
  Design Tip: For every additional ~90–100 units beyond the first 30, consider adding another lift to maintain reasonable waiting times and capacity.
• Lift Size and Accessibility: Each lift should meet wheelchair accessibility requirements per Approved Document M. The minimum internal car size is about 1100 mm × 1400 mm (standard 8-person lift)^[2], providing space for a wheelchair user and companion. Doors should have a clear opening of at least 800 mm. Controls, signage, and lighting must comply with BS 8300 for inclusive design.
• Firefighting Lift: If the building's top floor is over 18 m above fire service access level (a typical high-rise threshold in UK), include at least one firefighting lift within a protected shaft^[3]. A firefighting lift must be designed per BS EN 81-72 (or equivalent), with features such as an emergency power supply, special control mode for fire services, and a robust fire-protected lobby.
  
  Dimension: A firefighters' lift should have a minimum car size of 1100 mm × 1400 mm (w × d) to accommodate fire personnel and equipment^[4].
• Stretcher-Capable Lift: In taller buildings or those serving many units, at least one lift (often the firefighting lift) should be sized to accommodate a stretcher or ambulance trolley. BS EN 81-72 recommends a larger car — roughly 1100 mm wide × 2100 mm deep — if the lift may be used for casualty evacuation^[5]. Providing a stretcher-capable lift ensures emergency services can evacuate an immobile person during a medical emergency or fire.

Staircase Design and Egress (UK)

Standard Residential Stair Core

• A typical stair serving residential floors (with floor-to-floor height ~3 m) can fit in a shaft about 2270 mm × 3340 mm. This accommodates two straight flights of ~1.0 m width with a small landing in between^[6][7]. This configuration is suitable for regular apartment stairs, allowing comfortable access and meeting minimum space requirements for landings and headroom.

Fire Escape Stair (Exit Below Landing)

• If an escape route requires an exit door beneath a landing, additional headroom clearance (~2 m) must be provided under the stair. In practice, this results in a deeper stair shaft. For example, a design with an under-landing exit may need an overall well depth of around 4460 mm to achieve the 2 m clear headroom below the landing^[6][8]. This ensures compliance with egress requirements (no obstruction or head strike risk at the lower exit).

Stair Width

• Minimum clear width for common stairs in flats or public buildings is generally 1000–1100 mm (1100 mm is often used for residential apartments) to allow safe two-way passage during evacuations^[9]. Handrails or projections can affect effective width; refer to Approved Document K for detailed guidance on measurements.

Risers and Treads (Approved Doc K & BS 5395)

Stair geometry must adhere to UK limits for safety and comfort:

• Riser height: Between 150 mm and 220 mm for private stairs (within a single dwelling). However, for shared access or escape stairs serving multiple dwellings, a lower maximum riser is recommended — typically 170 mm max for better safety on evacuation stairs^[9][10].
• Tread depth (Going): Between 220 mm and 300 mm on private stairs. Stairs serving more than one dwelling or forming an escape route should have deeper treads, usually at least 250 mm going^[11] for a secure foothold during descent.
• Pitch and formula: The relationship between rise (R) and going (G) must satisfy 2R + G = 550 mm to 700 mm^[12][13]. This ensures a reasonable stair pitch (angle). In practice, private residential stairs often approach the steeper end (up to ~42° pitch), whereas communal or escape stairs are shallower (max ~38°) for ease of use by a wide range of people.
• Headroom: A minimum headroom of 2 m is required above any stair tread or landing (per Approved Document K) to prevent collisions. This is especially pertinent in designs with winders or curved flights.
• Handrails and Guards: All stairs must have secure handrails (both sides for wide or public stairs) between 900 mm and 1000 mm above pitch line, and guardings such that no gap exceeds 100 mm (to prevent falls, as per Approved Document K). These details ensure compliance with UK fall protection standards.

Escape Stair Provision (High-Rises)

• New high-rise residential buildings in the UK will be required to have at least two separate escape staircases if they exceed a certain height. Current regulatory changes (effective from 2026) set the threshold at 18 m or taller for residential buildings – such buildings must be designed with two independent stair shafts for evacuation^[14]. (Previously, a single staircase was allowed up to 30 m, but safety standards are now stricter.) Designers should incorporate a second stair core in high-rise schemes to meet these fire safety requirements.

Firefighting Shaft and Rising Mains

Firefighting Shaft

• In buildings with any floor above 18 m from fire service access, a dedicated firefighting shaft is required^[15]. A firefighting shaft typically comprises a protected stairway, a firefighting lift, and a fire-fighting lobby with a dry or wet riser (fire hydrant system) within. The shaft must be enclosed in fire-resisting construction (e.g. minimum 2 hours fire resistance for high-rise residential) to protect firefighters and evacuees. Ventilation (natural or mechanical) is required for the firefighting lobby to clear smoke^[16]. These provisions follow Approved Document B and BS 9999/BS 9991 guidance for fire safety in buildings.

Dry and Wet Risers (BS 9990)

Provide an in-building fire main (rising fire hydrant pipe) per BS 9990 in tall buildings:

• If the building's height is > 18 m but < 50 m (up to ~16 floors), a dry riser is typically acceptable^[17]. A dry riser is an empty vertical pipe with inlet breechings at ground level; fire services pump water into it during an incident^[18].
• If the building height is ≥ 50 m (approximately 17 floors or more), a wet riser must be installed^[19]. Wet risers are kept full of water and pressurized via pumps and tanks, ensuring immediate water supply at upper levels.
• The dry/wet riser includes landing valves (outlets) on each floor within the firefighting shaft for fire crews to connect hoses. The design and installation should strictly follow BS 9990 Code of Practice for non-automatic fire-fighting systems.

Firefighting Lobby

• Each floor served by a firefighting lift should have a firefighting lobby or vestibule, enclosed in fire-resisting construction, between the lift/stair and the rest of the floor. This lobby (minimum area and dimensions as per ADB/BS9999) acts as a buffer against smoke and heat. It must either have an openable external window of at least 1.5 m² or be ventilated by a smoke shaft system for smoke control^[20].

Waste Disposal (Refuse Chutes)

Refuse Chute Provision

• High-rise residential buildings often include a refuse chute system to allow convenient and sanitary disposal of garbage from each floor. Any refuse chute installation should comply with BS 5906:2005 (Waste Management in Buildings – Code of Practice). Local building guidance (e.g. Approved Document H) also encourages adequate waste storage and disposal facilities for new developments.

Chute Design

• A standard chute of ≈600 mm diameter is recommended for modern residential buildings to accommodate common waste bags without frequent blockages^[21]. The chute is typically constructed of steel and runs vertically through the building, opening into a sealed refuse collection room or bin at the base. Allow about 900 mm diameter clearance per floor for the chute penetration and proper installation^[21].

Fire Safety for Chutes

Refuse chutes must be designed with fire and smoke containment in mind, since they penetrate multiple floors:

• Hopper doors (the intake doors on each floor) should be fire-rated self-closing hatches with smoke seals and intumescent strips^[22][23]. This prevents fire or smoke from traveling up the chute if a fire occurs in the refuse area or a tenant accidentally disposes of burning material.
• The bottom of the chute is fitted with a robust fire closure plate (typically 6 mm steel per BS 1703 specifications^[24]) that automatically seals if a fire is detected in the bin room, containing the fire.
• The chute should be vented at the top (usually through the roof) to allow heat and smoke to exhaust safely and reduce pressure in case of fire, as well as to minimize odors^[25].
• Sprinklers or automatic fire suppression may be recommended inside refuse chutes and bins in some designs, although this is not explicitly mandated in all cases – designers should consult BS 5906 and local fire authority guidance.

Maintenance Access

• Ensure the design includes safe access doors for clearing blockages and periodic cleaning of the chute (which should be done regularly to avoid buildup of waste). Maintenance points are typically provided at the top or at bends in the chute, with lockable service doors.