Removing a load-bearing wall requires plans signed and sealed by an engineer to obtain the permit. Sizing the beam is only part of the job: the load has to be followed down to the foundation, where two bearing points replace a wall that spread the weight along its entire length.
Opening up between the kitchen and the living room is a very common renovation in Montreal. It's also the one where the gap between a well-run project and an improvised one shows up fastest, sometimes within the first year.
The work itself is simple: you remove a wall and put a beam in its place. All the work lies in what surrounds it, and above all in what's underneath.
How to recognize a load-bearing wall
A load-bearing wall takes the loads from the levels above and carries them down to the foundation. A partition wall carries only itself. Mixing the two up is costly.
A few clues can be checked without demolition. A wall that lines up from one storey to the next, a wall above the main beam in the basement, a wall perpendicular to the joists: in all three cases, the likelihood that it is load-bearing is high. Conversely, a wall parallel to the joists and present on only one storey rarely is.
These clues point the way; they don't settle the question. In Montreal plexes, a century of successive alterations has created situations where a wall that wasn't load-bearing originally became a support after a renovation. Only an on-site check decides.
A party wall is never an ordinary case
In a duplex or triplex, a party wall often carries both buildings. Any work then affects the neighbour's property and calls for a specific process, in addition to the structural checks.
What the engineer calculates before drawing
The beam isn't the first thing to be sized. You start by establishing everything it will have to carry.
We add up the dead weight of the floors, partitions and roof, add the occupancy live loads set by the code, then the snow loads for the upper levels. Then we look at what's above: a wall on the floor above, a stair opening, a bathtub, a future addition the client mentions in passing.
That total determines the beam, but also the columns that carry it, the support for those columns on the level below, and finally the footing under that support. This complete chain is what makes the difference between a plan and a sketch.
The four possible configurations
Once the loads are known, the next step is choosing how the beam fits into the building. The choice depends on the available depth, the span and the desired look of the ceiling.
- No dropBeam set within the floorThe most elegant solution: the ceiling stays flush. It requires enough joist depth and hangers to hang each joist from the beam. The work takes longer, the result is invisible.
- Visible dropExposed beam below the floorEasier to install and often more economical. The drop is treated as a design element rather than a flaw, especially when it marks the boundary between two spaces.
- With columnsIntermediate supports keptWhen the span gets too long, an intermediate column greatly reduces the size of the beam. It has to go down to a support able to carry it, not simply stop on the slab.
- Critical pointThe load path down to the foundationWhere the wall spread the load along its entire length, the beam concentrates it at two points. If the footing under those points wasn't designed for it, it has to be enlarged. This is the step improvised projects forget.
Steel or engineered wood
Both have their merits. The choice comes down to span, available depth and access.
| Steel | Engineered wood | |
|---|---|---|
| Depth required | Less, for the same span | More, which makes it harder to fit within the floor |
| Handling | Heavy, requires access and often several people | Carried in sections and assembled on site |
| Lead time | Fabrication to be ordered in advance | Available more quickly |
| Connections | Bolted or welded connections to be detailed on the plan | Nailing and bolting to a specific pattern |
| Where it's the right choice | Long spans, tight ceiling height | Typical residential spans, difficult access |
In triplexes in the Plateau or Rosemont, access is often the deciding factor. A twenty-foot steel beam won't go up a spiral staircase.
The plan, the permit and the order of things
Removing a load-bearing wall is an alteration. It requires a permit, and the permit requires plans signed and sealed by an engineer. This isn't red tape: it's what certifies that the change has been calculated.
The right order never changes. On-site check, calculations, sealed plans, permit application, then construction. Every change to this sequence creates a risk. Starting before the permit is issued exposes you to a stop-work order and, for a load-bearing wall, an obligation to restore the original condition.
What your insurer thinks
Structural work carried out without a permit or sealed plans can jeopardize a claim, and it often comes to light at resale during the pre-purchase inspection. The paperwork matters as much as the work.
How the work proceeds on site
The construction sequence matters as much as the sizing. A load-bearing wall isn't removed all at once.
- Temporary shoring on both sides of the wall, also sized by calculation. It carries the loads for the entire operation.
- Demolition of the wall in sections, once the shoring is in place and checked.
- Preparation of the supports: footing enlargement, bearing plate, column, as the plan specifies.
- Installation of the beam, shimming and fastening according to the connection details.
- Removal of the shoring only after the beam is fully loaded and the supports have been checked.
Shoring is the stage where accidents happen. It isn't improvised with 2x4s: it's calculated and drawn just like the permanent beam.
Costly mistakes
Four situations keep coming up in the remedial files we assess.
- The right beam, an inadequate support. The beam holds, so does the column, but the footing under the column was never enlarged. Settlement appears in the months that follow.
- The wall removed before shoring was complete. The floor above drops a few millimetres and never comes back up. The cracks in the ceiling remain.
- A change of material along the way. A wood beam substituted for the specified steel, without a new check, with a deflection that becomes visible under the doors.
- Forgetting the bracing. Some load-bearing walls also stiffen the building laterally. Removing them without compensating changes how the whole building behaves.
A well-sized beam on an improvised support is a problem moved, not a problem solved.
Timelines and documents to keep
Here's what to expect for the timeline, and what to keep at the end.
- The technical visit: usually a day or less. We take measurements, identify the direction of the joists, check the support on the level below and open up if needed.
- The plans: the timeline is stated in the service proposal; a single opening takes less time than a project affecting several levels.
- The permit: depends on the borough. A file where the architectural and structural plans are consistent can shorten this step.
To keep with your property documents: the sealed plans, the permit, and the compliance report if construction supervision was carried out. These are the documents a buyer will most likely ask for.
FAQ
How can I tell if my wall is load-bearing without demolishing anything?
Three clues are easy to check: does the wall line up from one storey to the next, is it above the main beam in the basement, and does it run perpendicular to the joists? A yes to any of the three makes the wall suspect. Confirmation requires an on-site check, sometimes with a small opening in the ceiling.
Do you really need a permit to remove a load-bearing wall?
Yes. It's an alteration to the building, and the municipality requires plans signed and sealed by an engineer before it issues the permit. Doing the work without a permit exposes you to a stop-work order, an obligation to restore the original condition and complications when you sell or file an insurance claim.
Can you avoid a dropped beam in the ceiling?
Often, yes, by setting the beam within the depth of the floor. Each joist is then hung from the beam with a hanger. This solution requires enough joist depth and more careful workmanship, but the ceiling stays perfectly flush. The plan has to provide for it from the design stage, not partway through construction.
What happens if the footing under the new column is too small?
It has to be enlarged before the load is applied. Where the wall spread its weight along its entire length, the beam concentrates it at two points. A footing not designed for that concentration settles, and the settlement then shows up in the floor and in cracks above the new opening. Checking the support is part of the assignment.
Can the party wall of a duplex be opened?
It's a special case that goes beyond the structural question alone. A party wall often carries both buildings and falls under a legal regime shared with the neighbour. Technically, an opening is still possible in some configurations, but it calls for a more detailed analysis and an agreement with the neighbouring party before any work.
A wall to open up in your project?
We check the existing structure, calculate the load path and produce the sealed plans required for the permit. The timeline is stated in our written service proposal.
Have Your Wall CheckedNote: Permit requirements vary from one borough to another. This text describes the usual technical process; it does not replace an assessment of your building.
Sources: Régie du bâtiment du Québec, Building chapter of the Quebec Construction Code. City of Montreal, alteration permits. Engineers Act (CQLR, c. I-9).