Light gauge steel framing in Colombia: NSR-10 Appendix F.4-A, its R0 values and the two-storey limit
By Germán Reisenauer, Civil Engineer · October 24, 2026 · EDICI Ingeniería, Paraná, Argentina
Until 2021, Colombia's national seismic code, the NSR-10, sent light gauge steel shear walls to AISI S213 but gave them no seismic coefficients of their own. Since Decree 1711 of December 13, 2021, it has a chapter for cold-formed steel framing: Appendix F.4-A, with seismic coefficients for five systems and a two-storey cap. It is little known and often misquoted. With the reconstruction after the August 10, 2026 earthquake, it is worth reading first-hand.
Short answer
- The coefficients: R0 = 5.0 with wood structural panels or steel sheet, 3.0 with straps, 2.0 with bolted frames and 2.0 with gypsum board (Table F.4.A.8-1).
- The cap: one or two storeys, in every seismic hazard zone. More storeys are not permitted.
- R0 is not R: the irregularity and redundancy factors of Title A apply, and there is no Cd: drift is checked with unreduced forces.
- Fibre cement: the table names it, but the appendix gives it no strength.
- Beyond the calculation: drawings that identify the seismic system, a sworn statement from the manufacturer and an independent technical review for every substitution.
What Appendix F.4-A is
Decree 1711 of 2021 amended the NSR-10 with a technical annex that, among other things, added to Title F (steel structures) Appendix F.4-A, "Seismic force-resisting systems with cold-formed steel members for one- and two-storey buildings". It has applied since publication, and the decree's recitals tie it to rural social housing.
- It works together with chapter F.4, the cold-formed steel chapter of the NSR-10, which is based on AISI S100-07. The appendix itself cites AISI S100-12 and S240-15. In a conflict, the NSR-10 governs, then the appendix.
- It does not cite AISI S400, the North American seismic standard for these systems, although a participant in the public consultation described it as the transcription of a chapter a subcommittee had prepared on the basis of AISI S400-15. The appendix's layout appears to follow S400, but we have not checked it: S400 is a paid standard.
- No decree has amended it since 2021. The 2023 decrees that touched the NSR-10 (1401 and 1580) deal with masonry housing.
In low seismic hazard zones, and only if R is taken as 1.5 for the seismic design forces, chapter F.4 is enough, with no special seismic requirements. In every other case the appendix governs.
The five systems and their coefficients
| Bearing wall system | R0 | Ω0 | Storeys, any hazard zone |
|---|---|---|---|
| Cold-formed steel framing sheathed with wood structural panels (F.4.A.5.1) | 5.0 | 3.0 | 2 |
| Framing sheathed with steel sheet (F.4.A.5.2) | 5.0 | 3.0 | 2 |
| Walls braced with flat straps (F.4.A.5.3) | 3.0 | 2.0 | 2 |
| Bolted cold-formed steel moment frames (F.4.A.5.4) | 2.0 | 1.5 | 2 |
| Framing sheathed with gypsum board or “fibrocemento” (F.4.A.5.5) | 2.0 | 2.0 | 2 |
Source: Decree 1711 of 2021, technical annex, Table F.4.A.8-1 "Seismic parameters" (p. 39 of the Ministry of Housing PDF). Descriptions translated and shortened by EDICI. In all five systems the same framing carries the gravity loads.
What the table does not say matters as much:
- No Cd, or any displacement amplification factor.
- No height limit in metres, only storeys.
- The appendix contradicts itself on bolted frames: the table says two storeys, but their own section (F.4.A.5.4.4.1) limits them to one-storey structures up to 10.7 m, with no column splices.
Each system has its own strength tables. Walls with wood structural panels (structural plywood or OSB) range from 8.5 to 45.0 kN/m per face, depending on the panel, the stud thickness and the screw spacing, with φ = 0.60 and an expected strength of 1.8 times the nominal. Steel sheet walls range from 5.69 to 30 kN/m, strap-braced walls are designed from the yield of the strap, and gypsum board walls range from 3.36 to 6.20 kN/m.
R0 is not R, and there is no Cd
The appendix refers to Title A for drift and irregularities. There, the force reduction coefficient is R = φa · φp · φr · R0: the tabulated R0 reduced for vertical and plan irregularities and for lack of redundancy (A.3.3.3). The φr factor is the delicate one: A.3.3.8 defines it for systems classified by energy dissipation capacity (minimum, moderate, special), and, as we read it, the F.4-A systems are not classified that way. Taking φr = 1.0 or 0.75 is a designer's decision that must be justified in the calculation package.
Our reading is that the missing Cd is not an oversight. In the NSR-10, drift is checked with the deflections of an analysis under unreduced seismic forces, and forces are divided by R only to design members (A.3.1.1). The limit is 1.0 % of the storey height for steel structures (Table A.6.4-1). Light gauge steel walls are flexible, so drift may govern.
Two storeys, not one more
F.4.A.8 states that only one- and two-storey buildings are covered and that more storeys are not permitted. According to a comment in the 2021 public consultation, the cap was not in the subcommittee's text or in AISI S400-15, the standard that text was based on, and that participant asked to remove it. Another asked to raise it to 12 m for walls with wood structural panels, steel sheet or straps. The Ministry accepted neither and said it would be discussed in the next update of the code.
For more than two storeys, or for a system other than the five, what remains are the routes of Law 400 of 1997: alternative methods backed by evidence and a statement of responsibility (art. 10), prefabricated systems not covered by the code, designed with the criteria of Title A or with the prior authorization of the Comisión Asesora Permanente, the national seismic code advisory commission (art. 12), and other systems authorized by that commission (arts. 13 and 14). Claims of three or four storeys of light gauge steel in Colombia find no support in the NSR-10.
The "fibrocemento" the table names
The fifth row of the table reads "yeso o de fibrocemento" (gypsum or fibre cement), with R0 = 2.0. But the section it points to, F.4.A.5.5, tabulates gypsum board and "panel de fibra", which the appendix defines as a board of lignocellulosic fibres, usually wood or guadua bamboo, 160 to 500 kg/m³, and which its requirements tie to ASTM C208 (cellulosic fiber insulating board). That is not fibre cement. For fibre cement, the appendix gives neither nominal nor expected strength.
It matters because fibre cement is the cladding of many reconstruction houses. If the board wall does not work, the practical route is to resist the earthquake with wood structural panels, steel sheet or straps, and treat the board as cladding. That is a designer's decision.
How much base shear, system by system
For the same house on the same site, the sheathing chosen to resist the earthquake changes the design force by up to 2.5 times. For a two-storey house in a city with Aa = 0.25 (effective peak acceleration coefficient) on site class D (Fa = 1.3), occupancy group I, on the plateau of the spectrum (Sa = 0.8125):
| F.4-A system | R0 | Design shear / weight, all φ = 1 | Design shear / weight, φr = 0.75 |
|---|---|---|---|
| Wood structural panels or steel sheet | 5.0 | 0.163 | 0.217 |
| Flat straps | 3.0 | 0.271 | 0.361 |
| Gypsum board (or what the table calls fibre cement) | 2.0 | 0.406 | 0.542 |
EDICI arithmetic with the NSR-10 spectrum (A.2.6) and R = φr · R0. Assumed soil profile; drift check not included.
With gypsum, the design shear is 2.5 times that of OSB: over 40 % of the weight of the house if φr = 0.75. In walls sheathed with wood structural panels, collectors, chord studs, hold-downs and anchors are designed for the expected strength of the wall, but need not exceed the seismic load amplified by Ω0 = 3.0 (F.4.A.5.1.4.1.2).
Materials, drawings and the manufacturer
- Steel: one of the specifications the appendix lists (NTC 5091, ASTM A1003, NTC 4011 and others). In the tabulated systems, ASTM A1003 Structural Grade 33 Type H for 0.84 and 1.09 mm and Grade 50 Type H from 1.37 mm, with studs of at least 89 mm web, 41 mm flange and 9.5 mm lip, at 610 mm maximum spacing. Thickness is base-steel thickness.
- Screws: ASTM C1513, No. 8 or larger, at least 9.5 mm from the edge.
- Hold-downs are part of the seismic system. The chord studs must transfer the uplift without the bottom track web having to resist it in bending or buckling. In our reading, that puts the hold-down on the stud, not on the track.
- Drawings (F.4.A.1.4): beyond what chapter F.4 requires, they must designate the seismic force-resisting system, identify its members and connections, and detail the connections between diaphragms and that system. For a panelizer, that is the panel drawing with its seismic walls marked.
- Manufacturer's statement (F.4.A.7.1): the manufacturer must declare under oath that it followed the quality-control procedures needed to comply with the appendix and the NSR-10.
- Substitutions (F.4.A.8.1): any substitution of components or connections within a system must comply with the NSR-10 and be approved through an independent technical review. As we read it, changing the screw, the stud thickness, the anchor or the board for ones not in the tables falls here. The appendix does not say who performs that review.
Who seals, and the reconstruction permit exemption
- The structural design is signed by a civil engineer with a current professional licence (matrícula profesional) who has demonstrated the required experience and qualifications to the advisory commission (Law 400 of 1997, art. 26). That engineer is responsible for the design.
- The review: the curaduría urbana (the local building-permit office) or the municipal office that issues the permit checks compliance. If the plot allows more than 2,000 m² of built area, an independent reviewer, different from the designer and not employed by them, must also sign the drawings. The rule also applies to groups of buildings approved on one or more plots that together exceed 2,000 m², even if each house has 48 m².
- Technical supervision during construction is mandatory in those same cases and in buildings that serve the community.
- Legislative Decree 1422 of September 17, 2026 (art. 20) exempts houses with a prefabricated seismic system from the building permit for two years, in the departments covered by the emergency and for people whose losses are certified. It exempts them from the permit, not from the code: the Ministry of Housing has to confirm NSR-10 compliance and, where applicable, the advisory commission's prior authorization (Law 400, art. 12). We have not yet found the Ministry's implementing rules.
As we read it, the NSR-10 does not certify systems or brands: Appendix F.4-A is a design route with requirements, and what falls outside it goes through Law 400. That is why "NSR-10 approved" or "NSR-10 certified" describes nothing.
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Frequently asked questions
How many storeys can be built with light gauge steel framing in Colombia?
Two at most under Appendix F.4-A of the NSR-10, added by Decree 1711 of 2021. The text is explicit: only one- and two-storey buildings are covered and more storeys are not permitted. During the public consultation a 12 m limit was requested for walls with wood structural panels, steel sheet or straps, and the Ministry answered that it would be discussed in the next update of the code. For more storeys, only the authorization routes of Law 400 of 1997 remain.
What R factor applies to light gauge steel framing under the NSR-10?
Table F.4.A.8-1 gives R0, not R: 5.0 for walls sheathed with wood structural panels or steel sheet, 3.0 for strap-braced walls, 2.0 for bolted frames and 2.0 for gypsum-sheathed walls. The irregularity and redundancy factors of Title A are applied to R0 (R = φa·φp·φr·R0), and the appendix gives no Cd: drift is checked with unreduced seismic forces.
Is fibre cement board accepted as shear wall sheathing under the NSR-10?
The seismic parameters table of Appendix F.4-A names “gypsum or fibrocemento” with R0 = 2.0, but the section it points to gives no strengths for fibre cement: it tabulates gypsum board and “panel de fibra”, which is a low-density wood-fibre insulating board. With fibre cement, the appendix has no source for the design strength of the wall.
Who seals the structural design of a light gauge steel house in Colombia?
A civil engineer with a current professional licence who has demonstrated the required experience and qualifications to the Comisión Asesora Permanente para el Régimen de Construcciones Sismo Resistentes (the national seismic code advisory commission), as required by article 26 of Law 400 of 1997. If the plot allows more than 2,000 m² of built area, or buildings approved on one or more plots exceed that area together, an independent reviewer who signs the drawings is also required.
Do prefabricated houses for the 2026 reconstruction need a building permit?
Legislative Decree 1422 of 2026 exempts houses whose seismic system is prefabricated from the building permit for two years, in the departments covered by the emergency and for people whose losses are certified. It exempts them from the permit, not from the code: the Ministry of Housing has to confirm that they comply with the NSR-10 and, where applicable, that they hold the advisory commission’s prior authorization.
Sources: Decree 1711 of December 13, 2021, Ministry of Housing, City and Territory of Colombia, and its technical annex (NSR-10 Appendix F.4-A: F.4.A.1.1, F.4.A.1.3 to F.4.A.1.5, F.4.A.2.1, F.4.A.5.1 to F.4.A.5.5, F.4.A.6, F.4.A.7.1, F.4.A.8, F.4.A.8.1 and Table F.4.A.8-1); global report of comments from the public consultation on the draft decree (Oct 6, 2021). NSR-10, Title A in its 2010 text (A.2.3, A.2.4 to A.2.6, A.3.1.1, A.3.3.3, A.3.3.8, Tables A.3-1 to A.3-4, A.4.2, A.4.3 and Table A.6.4-1) and Title F, chapter F.4. Decrees 1401 and 1580 of 2023. Law 400 of 1997 (arts. 4, 6, 10 to 15, 18 to 20 and 26, as amended by Law 1796 of 2016). Legislative Decree 1422 of September 17, 2026, arts. 2 and 20. Accessed October 24, 2026. AISI and ASTM standards are paid documents and are not reproduced; the numerical examples are EDICI arithmetic.