Engineered Slab Design for Detached Garage, Pickering
This project involved the structural design of a 40' × 33' detached garage featuring a second-storey storage loft.
Parsways was retained to provide OBC Part 4 engineering services, supporting the architectural BCIN designer in realizing a structure that exceeded standard prescriptive code limits.
Location: Pickering, Ontario
Completion: 2025
Sector: Residential – Accessory Structure
1. The Challenge
While the project footprint was typical for a garage, the structural requirements were not. The design called for a steel superstructure (W-beams and HSS posts) to support significant storage loads in the loft.
This created two primary technical constraints:
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Structural Loading: The steel columns imposed concentrated point loads that a standard residential slab could not support.
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Frost Protection: The client required a foundation solution that resisted frost heave without the cost and site disturbance of a traditional 1.2m deep trench excavation.
2. The Engineering Solution
We developed an OBC Part 4–compliant structural package tailored to the project’s loading conditions with an emphasis on constructability.
a. Reinforced Slab-on-Grade:
A reinforced slab-on-grade was designed to transfer concentrated steel point loads using thickened edges and bearing pads at HSS post locations, controlling settlement under combined vehicle and gravity loads.
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b. Frost-Protected Shallow Foundation (FPSF)
An FPSF system was detailed using vertical and horizontal rigid insulation to meet frost protection requirements while minimizing excavation and concrete volume.
3. The Outcome
The project architect received a fully stamped, permit-ready structural package that satisfied OBC part 4 compliance and building standards. The solution provided the client with a cost-effective, durable foundation capable of supporting the structure’s complex load path.