NBC hierarchy and implementation status

The Nepal National Building Code (NBC) was prepared by the Department of Urban Development and Building Construction (DUDBC) in 1993–94, with UNDP/UNCHS (Habitat) support, following the 1988 Udayapur earthquake. It was made mandatory by the government in 2003 (2060 BS).

Hierarchy

The NBC follows a four-level hierarchy, from the most sophisticated design to the simplest construction:

• Level 1 – International state-of-the-art: for very important or complex buildings, designers may use the latest international codes and practice (NBC 000 introduces these requirements).
• Level 2 – Professionally engineered structures (NBC 101–114): the main code documents for engineer-designed buildings: 101 material specifications, 102 unit weights, 103 occupancy loads, 104 wind loads, 105 seismic design, 106 snow loads, 107 fire safety, 108 site consideration, 109 masonry, 110 concrete, 111 steel, 112 timber, 113 aluminium and 114 construction safety.
• Level 3 – Mandatory Rules of Thumb (MRT): for ordinary buildings of limited size, built without detailed calculation: NBC 201 (RC frames with masonry infill), 202 (load-bearing masonry) and 205 (RC buildings without masonry infill).
• Level 4 – Guidelines for remote rural buildings: for earthquake-resistant construction of owner-built houses: NBC 203 (low-strength masonry) and 204 (earthen buildings).

Other codes give service and architectural requirements, e.g. NBC 206 (architectural design), 207 (electrical) and 208 (sanitary and plumbing).

The legal base is the Building Act 2055 (1998), the Building Rules, the Local Government Operation Act 2074 and the municipal building bye-laws.

Implementation status

• The NBC is mandatory in municipalities: building permits are issued only if the design follows the code. Since 2072 BS (after the 2015 Gorkha earthquake), more municipalities have applied it, many through an electronic building permit system, and the Mandatory Rules of Thumb are the basis for ordinary buildings.
• Weaknesses: poor enforcement in rural areas, few trained inspectors, little inspection after the permit stage, informal construction and low awareness. DUDBC and local governments are revising the codes (e.g. NBC 105:2020) and building capacity.