How to Build an Earthquake-Resistant House in Nepal: NBC 105 Guide

Nepal sits on the boundary where the Indian tectonic plate pushes under the Eurasian plate — the collision that raises the Himalaya and makes the whole country seismically active. The Gorkha earthquake of 12 Baisakh 2072 BS (25 April 2015 AD), magnitude 7.8, killed nearly 9,000 people and destroyed roughly half a million houses. The overwhelming majority of buildings that collapsed were unreinforced masonry and informally built structures never checked against any code.

Engineers repeat the same lesson after every earthquake: earthquakes do not kill people, badly built buildings do. A code-compliant house costs only modestly more than an informal one, because the critical items are good layout, correct rebar detailing, seismic bands and site supervision rather than expensive materials.

The legal framework is the Building Act 2055 BS (1998 AD), enacted to regulate construction so that buildings resist earthquakes, fire and other natural calamities. Under it and the Local Government Operation Act 2074 (2017), municipalities and rural municipalities enforce the National Building Code (NBC) through their building-permit (naksa pass) systems, so code compliance is not optional for a legally built house.

NBC 105, titled Seismic Design of Buildings in Nepal, is the core seismic chapter of the National Building Code, prepared by the Department of Urban Development and Building Construction (DUDBC) under the Ministry of Urban Development. First issued in 1994, it was comprehensively revised as NBC 105:2020 (2077 BS), and a second revision, NBC 105:2025 (2082 BS), followed in 2025. The principles below come from the 2020 edition and carry through to the 2025 revision.

The code's fundamental promise is life safety, not zero damage. A compliant building must withstand the design earthquake — ground shaking with a 475-year return period — without local or global collapse, keeping its stability and safe evacuation routes intact. Cracks and repairable damage are accepted; falling down is not. A second requirement, damage limitation, checks the building against smaller, more frequent shaking (a fraction of the life-safety force) so it remains usable without repair.

In engineering terms these two promises are verified as the Ultimate Limit State (ULS) and the Serviceability Limit State (SLS), and critical facilities such as hospitals are designed to a higher standard so they remain operational after an earthquake. This performance-based philosophy replaced the simpler approach of NBC 105:1994.

NBC 105:2020 maps Nepal into zones using a Seismic Zoning Factor (Z), the peak ground acceleration expected with a 475-year return period at that location. Table 4-5 of the code lists Z for selected cities: values range from 0.25 in trans-Himalayan towns such as Jomsom and Simikot to 0.40 in places including Nepalgunj, Dhangadhi, Bharatpur and Hetauda, while Kathmandu is assigned 0.35 and Pokhara 0.30. Z = 0.35 means design shaking of about 35 percent of the acceleration of gravity — severe by any standard.

On top of the zone factor, the code applies an Importance Factor (I) reflecting the consequences of failure. Ordinary structures, including normal houses, use I = 1.0. Schools, colleges, cinemas, shopping malls, temples and other assembly buildings designed for more than 500 people use 1.25. Hospitals, fire stations, police headquarters and power stations use 1.5, designed for 50 percent higher force so they keep functioning after the earthquake.

The practical takeaway is that the design force is neither negotiable nor uniform across Nepal: the same three-storey house needs measurably more seismic strength in Nepalgunj (Z = 0.40) than in Jomsom (Z = 0.25). Your engineer combines Z with the soil type and building period to compute the design base shear.

The same earthquake shakes different ground differently. NBC 105:2020 defines four site subsoil categories: Soil Type A (hard sites on rock or shallow dense material), Type B (medium), Type C (soft, deep soil) and Type D (very soft sites with more than 10 metres of very weak soil). Softer soil acts like jelly on a plate: it amplifies and prolongs shaking, especially the slow, long-period motion that affects taller buildings.

The code bakes this into its design spectrum. On Type A soil the high-demand plateau of the spectrum ends at a period of 0.5 seconds, but on Type D it extends to 2.0 seconds, so mid-rise and taller buildings on very soft ground must be designed for much larger forces than identical buildings on rock. Table 4-4 of the code assigns Type D to the core Kathmandu Valley municipalities — Kathmandu, Lalitpur, Bhaktapur, Madhyapur Thimi, Kageshwari Manohara and Tokha — reflecting the valley's deep, soft lakebed sediments.

This is why the 2015 shaking felt so violent in the valley, and why site investigation is worth the money. Have the soil tested before finalising a design; on soft or liquefaction-prone ground the code directs designers to account for potential soil movement and to prefer deep (pile) foundations, with advice from a geotechnical engineer.

Chapter 2 of NBC 105:2020 sets out principles for arranging a building's structure, and most cost nothing to follow at the sketch stage. Structural simplicity means the earthquake force has a clear, direct path from roof to foundation. Uniformity and symmetry mean columns and walls are spread evenly in plan and continue unchanged up the height, so no single spot is overstressed. Redundancy means many elements share the load, so one failure does not become a collapse.

The code also asks for adequate stiffness in both directions (earthquakes shake in every direction), torsional resistance achieved by placing strong elements near the building's edges, floors that act as rigid diaphragms tying walls and columns together, and foundations connected by tie beams so the whole building moves as one unit. In practice, the shapes that survive earthquakes are the boring ones: compact rectangular plans, equal storey heights and continuous columns.

The Building Act classifies buildings into four categories, and the one that matters for most self-builders is Category C: plinth area up to 1,000 square feet, up to three floors including the ground floor, and structural spans up to 4.5 metres. For this class the NBC provides Mandatory Rules of Thumb (MRT) — pre-engineered recipes that deliver code-level safety without a full custom structural analysis. NBC 201 covers reinforced-concrete (RC) frames with masonry infill, NBC 202 load-bearing masonry, and NBC 203 and 204 low-strength masonry and earthen buildings; in 2024 DUDBC added NBC 205:2024, a ready-to-use detailing guideline for RC residential buildings of up to three storeys using Fe500 deformed rebar.

For masonry houses, the life-saving details in NBC 202 are horizontal seismic bands and vertical corner steel. A continuous reinforced-concrete sill band runs through all walls below window level and a lintel band just above all openings, in every storey, tying the walls into a box. Vertical steel dowel bars are placed at wall corners and T-junctions, starting from the foundation concrete and grouted in M20-grade concrete, so the walls cannot peel apart at the joints. Band and dowel reinforcement is held by stirrups of at least 6 mm diameter at 150 mm spacing.

For RC frame houses, detailing quality decides survival: correct member sizes, closely spaced stirrups near beam-column joints, ties bent into 135-degree hooks with an extension of six bar diameters (at least 65 mm) so they cannot spring open, proper lap lengths and adequate cover. None of this is visible after plastering, which is why engineer supervision during pouring and honest bar-bending matter more than any finish item in the house.

Naksa pass (literally 'map/drawing approval') is the building permit issued by your municipality or rural municipality, and it is the legal gate through which NBC compliance is enforced. Drawings must be prepared by a registered engineer or designer, and municipal engineers check them against the building code and the local building bylaws (setback, height, floor-area and right-of-way rules) before approval. Large cities including Kathmandu and Lalitpur run this through an electronic Building Permit System (eBPS).

The process is staged. After you apply with your documents, the ward office verifies the site and posts a neighbour-notification notice (commonly a 15-day period) so adjoining landowners can raise objections. The municipality then issues a temporary permit that lets you build up to plinth (damp-proof course) level; a technician inspects the plinth against the approved drawing before the permanent permit is issued for the superstructure. On finishing, a completion certificate (nirman sampanna praman patra) follows a final inspection. In Kathmandu Metropolitan City the sequence takes roughly a month when documents are complete; fees vary by municipality, typically charged per square foot under local bylaws.

Building without a permit, or beyond the approved drawing, invites fines, demolition orders and resale and banking problems, since loans and land transactions increasingly require the completion certificate. Worse, it means no independent engineer ever checked whether your house can survive the earthquake NBC 105 plans for.

Earthquake-resistant detailing fails most often for economic reasons: the owner runs out of money mid-build and starts trimming steel, cement or supervision. The defence is honest quantity estimation before construction starts, so the budget covers the structure first and finishes later.

amarnepal.com's construction tools are built for exactly this stage. The rebar weight calculator converts your bar schedule into kilograms of steel so you can price reinforcement accurately, including the extra steel that bands, laps and hooks add. The concrete calculator gives cement, sand and aggregate quantities for M20 and other mixes; the brick and plaster calculators cover the masonry walls; the staircase calculator helps proportion a safe stair; and the water tank and septic tank calculators size the service structures whose weight your engineer must include in the design.

Used together with your engineer's approved drawings, these tools let you compare supplier quotes, catch contractors who under-order steel, and phase the work so that the earthquake-critical skeleton is never where savings are found.