OBC 2024 Guide: Sewage System Design Flows for Ontario Residential Projects
Sarah's Expert Insight
OBC Compliance Specialist
"Accurately calculating daily sewage flow is critical for project approval in London and luxury builds in Muskoka, where oversized dwellings often trigger complex Part 8 requirements. At empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure your septic design accounts for every fixture and square meter to avoid costly system failures or permit delays."
Understanding the 2024 Building Code Compendium requirements for sewage system design flows is essential for any property development or major renovation. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize compliance with Subsection 8.2.1.3. to ensure your project’s waste management system is both efficient and legal.
Overview of OBC 8.2.1.3. Sewage System Design Flows
The Ontario Building Code (OBC) dictates that sewage systems must be designed to handle specific daily sanitary flows. These values are determined based on the type of occupancy, the number of bedrooms, and the overall size of the dwelling. For residential projects, Table 8.2.1.3.-A is the primary reference for calculating these volumes in litres.
Residential Occupancy Standards (Table 8.2.1.3.-A)
Design flows for standard dwellings are scaled by bedroom count to ensure the septic or sewage system can handle the potential occupant load:
- 1 Bedroom: 750 Litres
- 2 Bedrooms: 1,100 Litres
- 3 Bedrooms: 1,600 Litres
- 4 Bedrooms: 2,000 Litres
- 5 Bedrooms: 2,500 Litres
Calculations for Large Dwellings and Additional Fixtures
For custom builds in areas like London or Muskoka, the code requires additional flow considerations for larger floor plans and luxury amenities:
- Increased Square Footage: For houses over 200 m², additional flow is added for every 10 m² of finished area.
- Bedroom Overages: Each bedroom beyond five adds 500 Litres to the daily design flow.
- Fixture Units: If your home features high-end plumbing with more than 20 fixture units, additional flow must be calculated at 50 Litres per unit.
Multi-Family and Commercial Occupancies
For apartments, condominiums, or boarding houses, the OBC uses per-person calculations (e.g., 275 Litres per person for multi-family dwellings). In mixed-use buildings, the design flow is the sum of all individual establishments within the structure.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.