Chapter A.10 of the NSR-10 sets out how to assess the seismic vulnerability of buildings built before the current code, and how to intervene in them. It applies when the building is extended, its structure is modified, its use changes, or it is strengthened or repaired after an earthquake (A.10.1.3). Minor repairs that do not affect the structure do not require it.
The cases
Change of use: for example, from residential to commercial, or to a higher occupancy group; it must be assessed even if the works are minor (A.10.1.3.2). Extensions: side additions or added floors (A.10.1.3.4). Strengthening: the seismic upgrade of an existing building (A.10.1.3.5). Earthquake damage: repair of moderate to severe damage (A.10.1.3.6).
The goal
That the building, once intervened, withstands small earthquakes without damage, moderate ones without structural damage and strong ones without collapse (A.10.1.2). To get there, the existing structure is studied: drawings, if there are any, a survey, materials testing and the state of repair, which the code turns into reduction factors for quality and condition.
In practice
Before buying a building to change its use, or before adding a floor, it is worth doing the study: the retrofit can change the project's budget. See our assessment and retrofit service and the guide when is a crack dangerous?.
Source: NSR-10, Title A, chapter A.10.
Frequently asked questions
When must a building's seismic vulnerability be assessed?
When it is extended, its structure is modified, its use changes or it is repaired after an earthquake (NSR-10, A.10.1.3).
Does a change of use require a structural review?
Yes. The NSR-10 requires the implications of the change of use to be assessed even if the works are minor (A.10.1.3.2).
