Structure, Foundations and Additions
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Structure, Foundations and Additions
We design and strengthen building structures across the Montreal area: sealed plans for your permits, additions and extra storeys, load-bearing wall openings, foundation stabilization, retaining walls. Every project starts with a site visit, never with a catalogue of solutions.
Our practice is built around Montreal's building stock: brick plexes, apartment buildings, foundations on clay, post-war fill. What we sign, we have seen with our own eyes.
- On siteA site visit before any calculation
- Written timelineTimeline for the plans stated in the service proposal, based on scope
- OIQPlans signed and sealed by a licensed engineer
I
Six areas of structural and foundation work
Designing means starting from an intention and making it buildable. Working on an existing building means starting from a structure that already stands and establishing what it can still carry. We do both, and they are two different crafts.
Structural plans for new buildings
Houses, cottages, plexes, small apartment buildings and commercial buildings. The work runs from the structural grid to the connection details, with a load table that makes the plans verifiable.
Additions and extra storeys
The question isn't how to draw the new volume. It's proving that the existing building can carry it. We follow the chain down to the footings, and we check them with test pits when the original plans are missing.
Load-bearing wall openings and removal
Removing a wall, widening an opening, opening up a floor plan. The beam is the easy part. The real work is following the load down to the footing, where two bearing points replace an entire wall.
Foundation stabilization and piles
When a support has lost its bearing capacity, piles transfer the load to a stable soil layer. That still has to be demonstrated: the diagnosis always comes before the quote.
Retaining walls
Holding back a slope, a sloped parking area or a neighbouring excavation. Soil pressure is calculated, drainage behind the wall is designed, and you never get one without the other.
Capacity analysis
A hot tub on a deck, mechanical equipment on the roof, a mezzanine in a warehouse, an attic conversion. Before adding a load, we check what the floor and its supports can actually take.
II
When the law requires a structural engineer
The rule is simple to state: as soon as a load-bearing element is modified, added or removed, the municipality requires plans signed and sealed by an engineer before it issues the permit. An experienced contractor can often install a beam correctly, but cannot size it or seal it.
The following work triggers this requirement in the Montreal area.
- Removing or cutting into a load-bearing wall, widening an existing opening, combining two rooms.
- Adding a storey or building an addition that bears on the existing structure.
- Designing a new structure, residential or commercial, including its foundations.
- Reworking a foundation: piles, underpinning, footing enlargement, structural repair.
- Adding a significant load: a hot tub on a deck, mechanical equipment on the roof, an attic conversion.
- Repairing damage after a flood, a fire or ground movement.
The principle behind it all
Every load needs a continuous path to the ground: from the roof to the floors, from the floors to the beam, from the beam to the columns, from the columns to the footings. Changing one link means checking every link that follows. That is why removing a wall is never just a matter of choosing a beam: the load that was spread along the full length of the wall is now concentrated at two points, and the footing under those points has to be able to carry it.
III
Steel, engineered wood or concrete: how we decide
The choice of material is rarely about looks. It comes down to the span, the depth available in the ceiling, site access and supply lead time.
| Material | Where it wins | Its limits |
|---|---|---|
| Steel | Long spans with a shallow beam depth, concentrated loads, heavy load transfers. | Fabrication lead time, demanding handling, corrosion protection. |
| Engineered wood | Everyday residential work, built-up beams that can be carried in through a stairway, quick availability. | Sensitive to moisture, with shorter spans for the same beam depth. |
| Concrete | Foundations, widened footings, slabs, underpinning. | Curing time, and a heavy dead load that has to be carried all the way down to the ground. |
In Montreal renovations, access almost always decides. A steel beam that is ideal on paper is useless if it won't fit through the basement door or if no crane can set up in the back lane. It's the first question we ask, before we size anything.
What stretches a schedule
Almost never the calculations. It's waiting for information: a land survey, a soil report, a client decision on the finished ceiling height, or missing original plans that force us to open up and see what is really carrying the load.
IV
Our approach, from the first call to the seal
The sequence doesn't change, whether the project is a ten-foot opening or an entire building. What changes is how deep each step goes.
- Scoping by phoneType of project, age of the building, existing plans, constraints from the architect or the contractor. This call tells us whether a visit is needed and what to prepare beforehand.
- Site visitMeasuring actual dimensions, locating load-bearing elements, noting joist direction and the condition of supports. Where needed, we open up to see what the finishes hide. One day is enough for the vast majority of buildings.
- Analysis and calculationsA complete load path analysis, checks on existing supports and footings, sizing of new members. This is where we determine what is possible, and at what technical cost.
- Producing the documentsFraming and foundation plans, general notes, connection details, a table of design loads. The document is signed and sealed, and it is made to be built from, not just filed.
- Follow-up during constructionWe stay reachable for the contractor's questions and come to the site at the key stages. A plan with no one to answer for it always ends up being interpreted.
V
What you receive, and how long it takes
A project is judged by what stays in your files once the work is done. Here is what we deliver, and the timelines to expect when your file is complete.
- A set of signed and sealed plans from an engineer who is a member of the Ordre des ingénieurs du Québec, suitable for your permit application.
- The table of design loads, which lets a third party check the design rather than take it on trust.
- Connection details at critical locations, so the contractor has nothing to improvise on site.
- An assessment report when the project involves an existing building: located and measured observations, causes, severity, and corrective measures precise enough for contractors to price.
- A certificate of compliance at the end of the work when we provide the supervision. It's the document the next buyer will ask you for.
Timelines to expect
- Site visit
- usually a day or less
- Structural plans, depending on scope
- stated in the service proposal
- Assessment report after the visit
- stated in the service proposal
- Crack movement monitoring
- several months
Movement monitoring has to cover at least one full freeze-thaw cycle. No single visit can establish that a crack is stable.
VI
FAQ
Which areas do you serve?
We cover the Island of Montreal and the surrounding region: Laval, Longueuil and the South Shore, the North Shore and the West Island. We know this territory from the angle that matters here, the soil. Sensitive clays, post-war fill and shallow foundations are not spread randomly across the map, and knowing where they are changes how we approach a diagnosis.
How much does a structural project cost?
It depends on three things, and none of them can be guessed in a thirty-second phone call: the scope of the project, the state of the existing documentation and the level of verification the building requires. An opening in a documented load-bearing wall doesn't take the same work as a foundation assessment on a century-old plex with no plans.
We scope the project during a first call, then send you a written proposal that details what is included and what isn't. You know what you are committing to before the work begins.
Do you work directly with my contractor or my architect?
Yes, and it's the most common situation. With an architect, the ideal is to come on board while the geometry can still be adjusted: a column grid shifted a few feet at the right time simplifies the whole structure. With a contractor, we stay reachable during construction for technical questions, which avoids decisions made in a rush.
What should I prepare before your visit?
Three things, and they save real time. The original plans if they exist, even partial, even old. Invoices or reports from previous work, which often explain what we observe. And an idea of when the thing that worries you first appeared, because that information guides the diagnosis more than any measurement.
For access, we need to be able to walk around the building and reach the basement or crawl space.
Do you also provide construction supervision?
Yes, and it's often the first step people cut to save money. It's also the only one that lets you state, years later, that the work was carried out as the plans intended. Supervision covers the key stages: the supports, the reinforcing steel before the pour, the loading of a beam, a pile reaching refusal.
Do I need a soil study for my project?
Not always, but often as soon as significant loads are added or the new foundation sits at a different depth from the existing one. In the region's clay areas, designing a foundation without knowing the soil's bearing capacity means working from an optimistic assumption. We tell you at the scoping stage whether your project needs one, and we coordinate the laboratory's work when it does.
Next step
Let's talk about your project
Describe the situation in a few sentences: the type of building, what you want to do or what you're seeing, and the deadline you're working against. We'll tell you frankly whether it calls for a visit, and what to plan for.
- Firm
- GC4I Inc., structural engineers
- Office
- 8350 Christophe-Colomb Avenue, Suite 18, Montreal
- Service area
- Montreal, South Shore, North Shore and across Quebec
- contact@gc4i.ca
The timelines on this page apply to a complete file. Permit requirements vary from one borough to another, and we check the ones that apply to your address before producing the documents.