2024 Ontario Building Code: Expert Guide to Dampproofing and Sound Transmission Standards
Sarah's Expert Insight
OBC Compliance Specialist
"At empcontracting.ca Inc. your construction contractor in London, Ontario, we emphasize that achieving the ASTC 47 rating is now a critical benchmark for multi-family developments in London and Oakville to ensure acoustic privacy. Furthermore, in the variable moisture conditions of Muskoka, strictly adhering to the drainage layer requirements of Section 5.7.3.4 is essential for long-term foundation protection and building envelope integrity."
Navigating the complexities of the 2024 Building Code Compendium is essential for high-quality residential and commercial builds. At empcontracting.ca Inc. your construction contractor in London, Ontario, we specialize in implementing these technical requirements to ensure your project is both compliant and durable.
Section 5.7.3.4: Permitted Dampproofing for Vertical Assemblies
According to the OBC, vertical building assemblies separating interior spaces from the ground may utilize dampproofing rather than full waterproofing under specific conditions:
Core Requirements for Dampproofing
- Hydrostatic Pressure: The assembly must not be subjected to hydrostatic pressure.
- Substrate Material: The substrate must be composed of cast-in-place concrete.
- Drainage Layer: A dedicated drainage layer must be installed between the soil and the building assembly.
Continuity is key; all joints, junctions, and penetrations must be designed to maintain the integrity of the dampproofing barrier.
Section 5.8.1: Protection from Airborne Noise
Sound insulation is a critical component of modern building comfort. The 2024 code sets strict minimums for separating dwelling units.
Required Sound Transmission Ratings
- Standard Separating Assemblies: Must provide an Apparent Sound Transmission Class (ASTC) rating of at least 47, or an STC rating of 50 when adjoining constructions meet Article 9.11.1.4.
- Elevators and Refuse Chutes: Construction separating these high-noise areas from dwelling units requires a minimum STC rating of 55.
Compliance and Measurement
Compliance is demonstrated via ASTM E413 and ASTM E90/E336 testing methods or by following the pre-approved assembly tables found in MMAH Supplementary Standard SB-3, "Fire and Sound Resistance of Building Assemblies."
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.