What is the minimum floor area for a BHU?

Each subdivided unit must have a floor area of at least 8 square metres (approximately 86 sq ft).

What are the ceiling height requirements for a BHU?

The clear ceiling height must be no less than 2.3 metres to ensure basic habitability.

Must the toilet and kitchen be separated?

Yes, the ordinance requires toilet and kitchen facilities to be separated to meet basic hygiene standards.

Does a mezzanine or loft count towards floor area?

Under the ordinance, spaces with a ceiling height below 2.3 metres do not count as effective floor area, so most mezzanines or lofts do not qualify.

Are there specific requirements for window size?

The ordinance requires each subdivided unit to have adequate natural light and ventilation, with the effective window opening area meeting a specified ratio of the floor area.

Must bathrooms have windows?

Bathrooms do not need windows, but must have a mechanical ventilation system meeting the required specifications to ensure adequate air circulation.

Can units share a bathroom?

No. Each BHU must have its own dedicated bathroom facilities and cannot share with other units.

Must non-compliant units be renovated?

Yes, units that do not meet minimum standards must be renovated by the specified deadline, or face enforcement action and fines.

Chapter 02 · Technical Standards

Minimum Living Standards:
6 Technical Requirements

Last updated: 2026.04.29

This article summarises the specific certification standards from a landlord's perspective. Each standard includes a "common non-compliance scenario" to help landlords anticipate what works their unit may require.

Minimum Internal Floor Area of 8 sq m

8 sq m minimum · including toilet · measured at internal walls

The "internal floor area" (including toilet) of each subdivided unit must not be less than 8 sq m.

Common non-compliance scenario: Subdivided flats in older buildings constructed before the 1980s often contain units of 6.5–7.5 sq m — "subdivisions within subdivisions." These typically require units to be merged.

Minimum Clear Ceiling Height of 2.3 m

2.3 m minimum · including below exposed beams and air-conditioning ducts

The lowest point of the ceiling in a subdivided unit must not be below 2.3 m.

Common non-compliance scenario: Rooftop structures, converted loft spaces, and added mezzanine floors frequently fail this requirement.

Mechanical Ventilation

Minimum 5 ACH · specific requirements for exhaust fan specification and duct dimensions

Each subdivided unit must be equipped with a mechanical ventilation system achieving a minimum of 5 air changes per hour (ACH).

Common non-compliance scenario: Units relying solely on natural ventilation through windows must have exhaust fans and ducting installed. This is the most common reason for rejection by the Buildings Department.

Separate Toilet

Self-contained · with WC / washbasin / shower · ventilation window or exhaust

Each subdivided unit must have a separate toilet (including WC, washbasin, and shower facility) — shared toilets are not permitted.

Common non-compliance scenario: Shared toilets were common practice in pre-2010 older-style subdivided flats. All units must now be retrofitted with individual, self-contained toilet facilities.

Independent Water and Electricity Metering

Separate water meter · separate electricity meter · independent circuit with individual isolation

Each subdivided unit must have independent water and electricity meters enabling separate measurement of consumption.

Common non-compliance scenario: The practice of sharing a single water and electricity meter across an entire floor and apportioning costs by ratio no longer complies with the Ordinance. Separate meters must be applied for through the Water Supplies Department and CLP/HK Electric.

Fire Compartmentation and Smoke Protection

FRR-60 fire door · smoke detector · fire extinguisher · FS251 application

The entrance to each subdivided unit must be fitted with a one-hour fire- and smoke-resisting door, and be equipped with a smoke detector and fire extinguisher.

Common non-compliance scenario: Timber doors, glass doors, and lightweight steel panel doors are generally non-compliant. They must be replaced with approved FRR-60 fire-resisting doors, and a Fire Services Department FS251 application must be submitted.

Next reading: Key Timeline — understand the critical dates for registration, certification, and enforcement.

Minimum Living Standards:6 Technical Requirements