When a home inspector flags a concern — a crack in the foundation, a sagging beam, floors that feel bouncy underfoot — the next step is often a call to a structural engineer. But many homeowners aren’t sure what that actually means. What does a structural engineer do that a home inspector doesn’t? What are they looking for, and why does it matter?
This post walks you through what a licensed structural engineer examines during a residential site visit, and why getting that second opinion can be one of the most important decisions you make as a homeowner.
A Structural Engineer Is Not a Home Inspector — and That’s the Point
A general home inspection is a broad overview of a property’s systems: roofing, plumbing, electrical, insulation, appliances, and general condition. It is an invaluable starting point. But when it comes to the structural skeleton of a building — the foundation, the framing, the load path from roof to ground — a home inspector is not the right professional to provide a definitive opinion.
A structural engineer is licensed under the Professional Engineers Act (Ontario) and is specifically trained to analyze whether a building’s structural systems can safely carry the loads they are designed to carry. According to Professional Engineers Ontario (PEO), a structural condition assessment must be a “methodical, scientific investigation with clearly defined objectives, carried out with sufficient rigour to provide reliable findings.” That level of rigour is what separates a P.Eng. assessment from a general walkthrough.
What We Look At: The Six Core Areas
1. The Foundation — The Most Critical Element
The foundation is the first thing I assess, and it often tells the most important story. In Ottawa, our climate is particularly hard on foundations. We experience some of the most severe freeze-thaw cycling in Canada — temperatures that can swing dramatically between winter and spring — which exerts relentless pressure on below-grade concrete and masonry walls year after year.
Crack type and orientation matter enormously. Not all cracks are equal:
- Vertical cracks are typically caused by shrinkage during the concrete curing process. They are common and often minor, though they can allow water infiltration if left unaddressed.
- Diagonal (stair-step) cracks in block or brick foundations often indicate differential settlement — the building shifting unevenly. Depending on severity and progression, these can range from cosmetic to structurally significant.
- Horizontal cracks are the most serious. They typically indicate lateral earth pressure is exceeding the wall’s capacity — meaning the soil outside is literally pushing the wall inward. The Ontario Building Code (OBC, Section 9.15) establishes minimum thickness and reinforcement requirements for foundation walls precisely to resist this kind of loading. A horizontal crack suggests those limits may be compromised.
Beyond cracks, I look for wall displacement or bowing — any measurable inward lean — and efflorescence, the white salt deposits that form when water migrates through masonry. Efflorescence itself is not a structural concern, but it is a reliable indicator of ongoing moisture intrusion, which over time can deteriorate mortar joints, corrode any embedded steel, and lead to more serious degradation.
2. The Floor System — Beams, Joists, and Posts
From the foundation, I move to the floor structure above: the beams, joists, and columns or posts that carry the loads of the living space above.
I’m looking for:
- Deflection or sagging in beams and joists beyond acceptable limits
- Notching or drilling of joists by trades (plumbers, electricians) that may have compromised their structural capacity
- Wood rot or pest damage — particularly in areas near grade or with a history of moisture
- Undersized members — older Ottawa homes, especially those built before the mid-20th century, were often framed with members that don’t meet current standards, and may have been altered over the decades without engineering review
- Posts and columns showing signs of crushing, rot at the base, or inadequate bearing on the footing below
Bouncy or sloped floors upstairs are often the symptom that sends homeowners to a structural engineer. The cause is almost always somewhere in the floor system below.
3. Load-Bearing Walls — The Hidden Skeleton
Many homeowners are surprised to learn that not every wall in their home is just a partition. Load-bearing walls carry the weight of floors and roofs above and transfer it down to the foundation. Removing or modifying them without engineering review is one of the most common — and costly — mistakes made during renovations.
During a site visit, I identify which walls are load-bearing by tracing the load path from the roof down. I look for:
- Signs of unauthorized removal or modification — a beam that was added in an awkward location, a wall that was partially removed with no header installed above
- Sagging or cracking at door and window headers — the horizontal members that span above openings
- Transfer of loads to non-structural elements — a scenario that can develop gradually and go unnoticed until a significant distress event
4. The Roof Structure
I assess the roof from the attic whenever accessible. The goal is to evaluate the framing — rafters, collar ties, ridge board, and any trusses — for signs of:
- Overspanning or inadequate sizing
- Spreading — where rafter thrust pushes the tops of exterior walls outward
- Moisture damage, rot, or pest activity in the sheathing and framing members
- Improper modifications — attic conversions or storage additions that were added without accounting for the additional load
In Ottawa, roof structures must be designed for significant snow loads. The National Building Code of Canada (NBC) specifies ground snow loads for our region, and any deficiency in the roof framing can become critical during a heavy snow year.
5. Exterior and Accessory Structures
The main house isn’t the only structure that deserves attention. Detached garages, covered porches, and garden suites are often the most neglected structures on a property — and the most deteriorated. I look at:
- Foundation condition — frost heave, settlement, and cracking in detached garage pads and perimeter walls
- Roof and wall framing integrity — particularly in older garages where years of deferred maintenance compound
- Connection to the main structure, if applicable
A deteriorated detached garage may not threaten the main house, but it can pose safety risks — and its condition often signals how the property as a whole has been maintained.
6. Visible Signs of Movement Throughout the Home
Finally, I pay close attention to evidence of movement that shows up throughout the living spaces:
- Doors and windows that stick, drag, or no longer close properly
- Diagonal cracks at the corners of door and window openings in drywall or plaster
- Gaps between walls, floors, and ceilings
- Sloped or uneven floors, detectable by eye or by level
These symptoms don’t diagnose the problem on their own — but they help me triangulate where distress is originating and how it may be progressing.
What You Get at the End: A Site Visit Report
After the assessment, you receive a written report under my professional seal. This is not a generic inspection form — it is a document prepared by a licensed Professional Engineer, in accordance with PEO’s Structural Condition Assessments of Existing Buildings and Designated Structures guideline (2016), documenting my observations, findings, and recommendations.
That report is the basis on which remedial work is scoped, contractors are briefed, and, if necessary, building permits are obtained. It is your evidence that the structure was evaluated by a qualified professional — and it travels with the property.
When Should You Call a Structural Engineer?
You don’t need to wait for something alarming to justify a site visit. Consider calling a structural engineer when:
- You’re purchasing a home and the home inspector has flagged concerns
- You’ve noticed new or widening cracks in your foundation or interior walls
- You’re planning a renovation that involves walls, beams, or structural modifications
- Your floors feel uneven, bouncy, or sloped
- You’ve had water intrusion in your basement
- Your home is older and has never been structurally assessed
Ready to Talk?
At Sinitski Structural Engineering Ltd. (SSEL), I provide residential structural assessments and site visit reports across the Ottawa area. If you have concerns about your home’s structure — or simply want peace of mind before a purchase or renovation — I’d be glad to help. Contact SSEL today if you wish to schedule a visit!