Many neighbourhoods in Lévis, such as Saint-Romuald, Charny and Saint-Nicolas, have bungalows built between the 1960s and the 1980s. When a family needs more room, adding a storey gains living space without giving up the yard. It's often feasible, but the house wasn't designed to carry a second level. Before asking contractors for quotes, you need to confirm the structure can handle it.
The foundation
All the weight of the new storey goes down to the footings. A bungalow's footings were sized for one storey, and the Code calls for wider footings under a two-storey house. The engineer therefore needs to know the width and condition of the existing footings, which often means a small test excavation. Soil matters too. Soft clay or poorly compacted fill doesn't behave like firm ground.
If the footings aren't adequate, they can be widened or reinforced in certain areas. That work is done in sections under the existing house, and it weighs heavily on the budget. It's better to know before the architectural plans are drawn.
The walls and the new floor
A bungalow's exterior walls, often framed with 2 × 4 studs, currently carry the roof. With another storey, they'll also carry a floor, walls and a new roof. The studs, the headers over the windows and the interior load-bearing walls all need to be checked.
The existing ceiling usually can't serve as a floor. In a bungalow, it's often formed by the bottom chord of the roof trusses or by light joists, sized to carry drywall and insulation rather than people and furniture. New floor joists are usually added, which raises the building and has to be planned for.
Load path and stability
The loads from the new storey need an uninterrupted path down to the foundation. If an upstairs load-bearing wall doesn't line up with a wall or beam below, a transfer beam is needed. The house also has to keep enough resistance to lateral loads from wind and earthquakes. A taller house catches more wind.
Other checks
Zoning sets a maximum height and sometimes a maximum number of storeys. In Lévis, an addition requires a permit, and heritage sectors go through an additional review. The project also affects the building envelope, the stairs, plumbing and heating. Those aren't structural questions, but they influence the engineer's choices.
Start with a feasibility study
Before paying for full plans, a site visit and a structural feasibility study tell you whether the project makes sense and what reinforcement to expect. That way you don't discover a foundation problem after the architectural plans are finished. If the project goes ahead, the engineer then prepares the signed and sealed structural plans for the permit.
We carry out this kind of study for houses in Lévis, on the South Shore and across the Quebec City area. See our building and structure service or get in touch to describe your project.
This article is provided for general information. Whether a storey can be added depends on each building, the soil and the applicable municipal regulations.