Adding a second floor to your house
Before adding a floor you need to know whether the house can carry it.
Photo: Declan Sun / Unsplash
To build a second floor on an existing house, a civil engineer must check the existing structure and design the addition: the NSR-10 (Colombia's seismic-resistant building code) treats it as a vertical extension (A.10.6.1 and A.10.8), in which the house and the new floor work together. DDES does that assessment, the design and the drawings the curaduría urbana (the building-permit authority) asks for.
- Code
- NSR-10, A.10.8
- Service
- Structural design
- Permit
- Building permit
What to have at hand
- Drawings of the house, if they exist, or a survey of what is built.
- The property title certificate and deed.
- Photos of the columns, beams, walls and any visible crack.
- What you want to build on top: number of floors, use and rough layout.
How we solve it
- Site visit and survey of the existing structure: dimensions, visible reinforcement and condition.
- Check of the foundation and columns under the loads of the new floor, with a soil study when the code requires it.
- Design of the addition and, if needed, of the strengthening of what exists.
- Signed drawings and calculations to file the permit at the curaduría urbana.
What does the NSR-10 say about adding a floor?
The NSR-10 calls this a vertical extension (A.10.6.1). The existing and the new structure work together (A.10.8.1), so designing the new floor is not enough: the columns, beams and foundation below must be shown to carry the loads and the earthquake with the extra floor.
What if the house is masonry?
Title E of the NSR-10 gives requirements for one- and two-story houses of confined masonry (E.1.1.1). A one-story house built with that system can grow to two if its walls, tie-columns and footings meet them; if they don't, it must be strengthened first.
Technical notes
One- and two-story houses: what Title E of the NSR-10 requires
Foundations, confined walls, openings and tie columns: the minimums for building an earthquake-resistant house.
Existing buildings: when the NSR-10 requires an assessment and a retrofit
Changes of use, extensions, structural alterations and earthquake damage: what chapter A.10 requires.
Geotechnical study: how many borings, and how deep, the NSR-10 requires
The building's category sets the minimum number of borings and their depth. Title H sets it out.
Frequently asked questions
Do I need a permit to build a second floor?
Yes. Extending a building requires a building permit from the curaduría urbana, which asks for structural drawings and calculations signed by a civil engineer (A.1.3.4 and A.1.5).
Can any house carry a second floor?
No. It depends on the foundation, the columns and beams, and the soil. Many one-story houses were built without planning to grow and need strengthening before adding a floor.
Is a soil study needed?
The NSR-10 requires subsurface exploration for buildings (A.1.3.2). The engineer sets its scope based on the size of the addition and what is known about the soil.
What does DDES deliver?
The assessment of the existing structure, the design of the addition and of any strengthening, and the signed drawings and calculations for the permit.
Other situations
- Home structural retrofitSo an older structure resists what today's code requires.
- Crack assessmentNot every crack is serious, but every crack that grows needs to be studied.
- Warehouse designFrames, roof, floor slab and foundation, designed together.
- Retaining wallsFor basements, level changes and sloping lots.
- Tanks and poolsStructures that must not only stand but also not leak.
- Steel mezzanineMore usable floor area inside the same warehouse or store.
- Building permitWhich structural documents the curaduría asks for and who signs them.
Last updated:
Contact
Want to add a floor?
Tell us about the house and what you want to build. A DDES engineer tells you what you need.
Our team works in Spanish. You can write to us in English and we will get back to you.
Photo: Julia Taubitz / Unsplash