Roofing in Hong Kong

Hong Kong is one of the most densely built places on earth, and almost all of its people live and work under flat reinforced-concrete roofs on multi-storey buildings. Pitched clay-tile roofs survive mainly in the walled villages and temples of the New Territories and on a few early urban buildings. Typhoon winds, intense rain and the pressure of space have shaped roofs more than any architectural style.

Climate and hazards

The city has a humid subtropical climate with a wet summer monsoon and frequent tropical cyclones. The Hong Kong Observatory has issued warnings since 1884 and has used a numbered signal system since 1917, revised to ten signals in 1931. The highest, the No. 10 Hurricane Signal, warns of sustained winds of 118 km/h (73 mph) or more, with gusts that may exceed 220 km/h (137 mph). By the end of 2025 it had been hoisted only 19 times since 1946, six of them since 2010, including Typhoon Hato (2017) and Typhoon Mangkhut (2018). Wind loads on roofs, parapets, rooftop plant and temporary structures are therefore a central design concern.

Roofing history

Villages. Before the colonial era, roofs in the area were those of southern Chinese villages: timber-framed pitched roofs covered with clay pan-and-cover tiles. About 70-80 walled villages survive, most in the New Territories, built by Punti and Hakka clans as defence against pirates during the Ming and Qing dynasties. Kat Hing Wai in Yuen Long was founded by the Tang clan in the 17th century; Tsang Tai Uk in Sha Tin, a Hakka stronghold of granite, grey brick and solid timber, was begun in 1847 and took about 20 years to build.

Tong lau. From the late 19th century until the 1960s, the typical urban building was the tong lau, a narrow shophouse tenement of two to four storeys at first. Early tong lau had timber and tile roofs. After an outbreak of bubonic plague, regulations of 1903 required light wells and larger windows and replaced tiled roofs with flat concrete roofs. From the 1920s reinforced concrete became the main structural material, and post-war tong lau often had flat roof terraces that owners later built over to gain living space. Height controls were relaxed in 1955 to cope with migration from the mainland, and after further rule changes came fully into force in 1966 no more tong lau were built.

High-rise era. Since the 1960s, public and private housing has been dominated by high-rise towers with flat concrete roofs carrying water tanks, lift machinery, plant and, in some cases, rooftop structures added without permission.

Traditional and vernacular roofs

• Village houses and ancestral halls - gabled, grey clay-tile roofs on brick or granite walls, with decorated ridges on halls and temples.
• Tong lau - early timber-and-tile roofs, later flat concrete roof terraces.
• Temples - southern Chinese ridge decoration with ceramic figures; ridge figures also help weigh down roof tiles.

Roofing today

Nearly all buildings have flat reinforced-concrete roofs waterproofed with membranes or liquid coatings, usually with screeds, tiles or insulation above and heavy rooftop equipment. Unauthorised rooftop structures have long been a safety issue: the Buildings Department's ten-year removal programme, run from 2001, prioritised illegal rooftop structures on single-staircase buildings, and a revised policy from 1 April 2011 extended enforcement to unauthorised works on rooftops and podiums regardless of risk level.

Codes, standards and regulation

Building work is controlled under the Buildings Ordinance (Cap. 123) and its regulations, including the Building (Minor Works) Regulation, administered by the Building Authority through the Buildings Department, formed in 1993 as successor to the Buildings Ordinance Office. Wind loads are set by the Code of Practice on Wind Effects in Hong Kong 2019, which replaced the 2004 code after a 12-month transition from 30 September 2019 and added, among other things, guidance on wind loads on temporary structures and on sheltering by surrounding buildings.

Notable roofs

• Tsang Tai Uk, Sha Tin (begun 1847) - one of the best-preserved Hakka walled villages.
• Kat Hing Wai, Yuen Long (17th century) - walled Punti village, though most houses inside have been rebuilt.
• Surviving tong lau in older districts, showing the shift from tile to flat concrete roofs.

Local roofing terms

• tong lau (唐樓) - "Chinese building", shophouse tenement
• wai (圍) - walled village

Sources and gaps

Roof-material statistics, industry data and detailed historical roof surveys: published information is limited.