Title E of the NSR-10 sets the minimum requirements for building one- and two-story houses in confined masonry or cement-plastered bahareque (timber-and-earth walls), without a full structural calculation. It applies to occupancy group I homes that are part of programs of at most 15 homes and less than 3,000 m² built (E.1.1.1.1). If the house uses another structural system, is part of a larger program or has another use, it must be designed under Titles A to D.
The foundation
The foundation is a grid of reinforced concrete beams forming closed rings (E.2.1.4). The bottom of the beams must be at least 500 mm below the finished level of the first floor, and on top of them goes a plinth that projects at least 80 mm (E.2.2.4). Before building, the responsible professional must record in a signed statement how the neighboring houses have performed: settlement, cracks or expansive soils (E.2.1.1). If there are signs of trouble, a geotechnical study under Title H is required.
The walls and their openings
Openings must be small, well spaced and never at the corners. The area of openings in a wall may not exceed 35% of its total area, and there must be more than 500 mm between two openings (E.3.4). Walls must be distributed in both directions and symmetrically, with a minimum length of confined walls in each direction that depends on the built area and the seismic hazard zone (E.3.6).
Tie columns and tie beams
Every structural wall is framed by reinforced concrete tie columns and tie beams of at least 200 cm² in cross-section (E.4.3.2 and E.4.4.2). The columns go at the ends of the walls, at their intersections and at spacings of no more than 35 times the wall thickness, 1.5 times the height between horizontal ties, or 4 m (E.4.3.3). The beams form closed rings at foundation, floor and roof level.
When to call an engineer
If you want to enlarge the windows beyond those limits, remove walls, build a third floor or change the system, the house falls outside Title E and needs a structural design. The same applies if the ground shows settlement or expansive clays. See our structural design service.
Source: NSR-10, Title E, chapters E.1 to E.4.
Frequently asked questions
Does a two-story house need a structural design?
If it is confined masonry or cement-plastered bahareque, in occupancy group I, and part of a program of at most 15 homes and less than 3,000 m², it can be built to the minimum requirements of Title E. Outside those limits it needs a design under Titles A to D.
How many windows can a wall have?
The area of openings in a wall may not exceed 35% of its total area, and there must be more than 500 mm between openings (NSR-10, E.3.4).
