Parsways Structural Engineering Blog

Existing decks in Ontario may need more than a repair estimate. For condominium and multi-unit properties, the concern is often structural condition, code compliance, missing drawings, and safe future use. A structural review of existing decks is commonly needed when the deck was built years ago, the original drawings are unavailable, or a change is proposed. This includes deck extensions, altered access, or a “door to nowhere” condition. Existing Deck Condition Assessment Ol

In many Ontario construction projects, existing concrete slabs are often assumed to have sufficient strength for new loading conditions. In practice, the structural capacity of existing slabs in Ontario is rarely defined with certainty. Across industrial and commercial buildings in Ontario, including major urban centres such as Toronto and surrounding regions, changes in use, storage demand, or equipment installation frequently introduce loads that were not part of the origin

Garage slabs are often perceived as simple concrete surfaces. In reality, they act as part of a soil-supported structural system that transfers loads, responds to subgrade conditions, and must perform under Ontario’s freeze-thaw environment. From a structural engineering standpoint, even a typical residential garage slab requires careful design to ensure long-term performance and compliance with local building requirements, including the Ontario Building Code (OBC). Structur

In Ontario construction, shear keys are commonly included in wall–footing details for basement walls, retaining walls, and foundation systems subject to lateral loading. The intent is to improve sliding resistance by providing mechanical interlock at the interface. However, in many projects, the use of shear keys is not always explicitly supported by project-specific shear calculations. As a result, the detail is often carried forward as part of standard sections rather than

A Letter of Exemption (LOE)  is sometimes requested when warehouse racking systems or mezzanine platforms are installed in industrial and commercial buildings across Ontario. The letter is issued by a professional engineer to confirm whether the proposed installation requires a building permit or structural review under the Ontario Building Code (OBC). In many warehouse projects, storage systems such as pallet racking may appear structural but function as equipment installe

A third-party structural review in Ontario  is an independent technical assessment of structural design documents prepared by another engineer. The purpose is to verify compliance with the Ontario Building Code (OBC – current edition) , referenced CSA standards, and accepted engineering practice. This process is commonly required for complex, high-risk, or unconventional structures. Municipal building officials, project owners, insurers, or peer engineers may request it. Regu

In Ontario warehouses, when installing or changing industrial pallet racks, a Pre-Start Health & Safety Review (PSR) may be required. This applies when racks are new or significantly modified and could pose a safety risk if they fail. Typically, this requirement applies when the racking system adds significant weight, requires anchoring, or affects stability. A licensed Professional Engineer (P.Eng.) must complete and sign off on the review when required, providing the P.Eng

In Ontario construction projects, a structural engineer site inspection may be required as part of the permit process. In practice, this is the engineer’s “general review” site visit—an on-site observation to confirm that the work observed is generally consistent with the sealed drawings and the Ontario Building Code (OBC). These inspections are not general quality checks; they are targeted engineering reviews tied to specific structural elements. For contractors, understandi

Mortise and tenon joints are among the earliest forms of timber connections still encountered in contemporary structural engineering practice. Today, the mortise and tenon joint  is most commonly reviewed by structural engineers as part of renovation projects, porch framing, or architecturally exposed timber assemblies in Ontario. From an engineering perspective, these joints are evaluated as load-carrying connections with specific behavioural limits, rather than as traditi

Timber grades Canada play a central role in how wood members are selected and evaluated for structural use in Ontario. In structural engineering, timber is not treated as a uniform material; its performance depends on both the species of wood and the grade assigned through standardized timber grading systems. In Ontario renovations and structural alterations, understanding these distinctions is essential for predictable load paths, acceptable deflection behaviour, and complia

Flitch plate beams  are composite members that combine timber and steel to increase bending capacity without increasing beam depth. In Ontario renovations and structural alterations, they are often considered where architectural constraints or headroom limits make all-wood beams impractical, while steel-only solutions may be difficult to install or integrate. A flitch plate beam is not simply a stronger piece of wood. Its performance depends on effective composite action betw

In reinforced concrete design, lap splices are not a drafting formality. They are a force-transfer mechanism . A lap splice allows tensile force to pass from one reinforcing bar, through the surrounding concrete, and into the adjacent bar. Its performance depends on bond behaviour , detailing, and how forces are distributed within the section. CSA A23.3 addresses this behaviour by classifying tension lap splices as Class A  or Class B . These classes do not describe construct

In structural concrete design, durability is defined , not assumed. CSA A23.1 addresses durability through concrete exposure classes , which link concrete performance requirements to the environmental conditions an element is expected to experience over its service life. Exposure classes are not a measure of concrete “quality” or strength. They reflect an engineering assessment of environmental risk —moisture, freeze–thaw cycling, and potential chloride access. If exposure is

Understanding when to use U-Fill ( Controlled Low-Strength Material / Flowable Fill)  versus Lean Concrete  helps engineers, contractors, and project managers choose the right material for trench backfilling, sub-bases, bedding, or void filling in Ontario projects. This comparison covers properties, typical uses, performance differences, and practical considerations from a structural engineering  perspective. What Is U-Fill (Flowable Fill / CLSM)? U-Fill  — also called flow

Residential underpinning is often treated as “mass concrete,” but durability is primarily an exposure issue . In concrete foundation underpinning , tight access, segmented pours, and variable curing conditions mean small field adjustments can significantly affect long-term performance. When underpinning is adjacent to a driveway, de-icing salts and surface runoff  can introduce chlorides at construction joints near grade. This shifts the focus from strength alone to durabil

The freeze–thaw climate across Ontario makes durability just as critical as strength. Even well-designed concrete can deteriorate early if it lacks the right amount of entrained air . The air content test for concrete is the primary field check engineers use to verify that fresh concrete is suitable for exterior slabs, driveways, foundations, and other elements exposed to moisture and freezing. This article explains how the test works, why it matters, and what acceptable resu

When planning a residential addition, commercial renovation, or new industrial building, most of the attention naturally goes to the visible structure.  However, one of the most influential factors affecting long-term performance lies underground: the groundwater table. Understanding how groundwater behaves is essential for designing footings that remain safe, durable, and compliant with Ontario engineering standards. 1. What Is the Ground Water Table ? The groundwater table

Concrete is a key material in foundations, slabs, and structural elements. In Ontario’s climate—with frequent freeze–thaw cycles and rapid temperature changes—verifying concrete quality is essential to ensure long-term performance. Concrete testing methods confirm that both fresh and hardened concrete meet required strength, durability, and code standards under OBC and CSA A23.1/A23.2. Why Concrete Testing Matters Even small variations in mix proportions, temperature, or pl

Bolted steel connections are crucial in determining how structures respond to various loads, from everyday gravity to wind, vibration, and seismic activity. In Ontario’s industrial and commercial sectors, the choice between Bearing-Type and Slip-Critical connections is more than a matter of preference; it significantly influences structural performance, installation costs, and long-term durability. Both systems are accepted under CSA S16 (Design of Steel Structures) , but

A Pre-Start Health and Safety Review (PSR) is an engineering review required under Ontario’s Occupational Health and Safety Act (OHSA), Regulation 851. It ensures that new or modified structures, racking systems, and industrial setups are safe, compliant, and structurally sound before use. In simple terms, a PSR is a proactive engineering process that confirms everything is designed and built to perform safely before the system is put into service. When Is a PSR Required? A P