ICF Meets the 2024 Ontario Building Code.
Every Time. Here’s Exactly How.

What Changed: The 2024 OBC and ICF

The 2024 Ontario Building Code (O. Reg. 163/24) came into force on January 1, 2025, replacing the 2012 OBC (O. Reg. 332/12). The Province describes it as the largest harmonization with the National Building Code in Ontario’s history — removing roughly 1,730 technical variations and bringing Ontario in line with the National Building Code 2020.

A three-month transition window ran until March 31, 2025 for designs already substantially in progress. Since April 1, 2025, every new residential permit application in Ontario must comply with the 2024 edition. If you’re building in 2026, the 2024 OBC is the only code that applies.

For ICF specifically, the changes that matter most are in three areas: SB-12 (Energy Efficiency), Section 9.32 (Ventilation — HRV/ERV and MVDS), and the explicit recognition of "Insulating Concrete Form (ICF) Units — Material Properties" in Division B Part 9.

Structural Integrity & Reinforcement

The 2024 OBC (Division B, Part 4 and Part 9) sets strict standards for reinforced concrete wall construction — including minimum concrete compressive strength, rebar sizing and placement, wall thickness, and the ability to resist vertical loads and lateral forces including wind and seismic requirements applicable to Ontario climate zones.

ICF wall systems are engineered with a reinforced concrete core typically ranging from 4″ to 8″ thick for residential, with 10″ and 12″ cores available for taller walls and commercial work. When properly designed with the correct reinforcement schedule, ICF walls meet or exceed all 2024 OBC structural requirements for residential and light commercial construction. For more on structural performance specifically, see our ICF structural strength guide.

• ✓Minimum concrete strength: 20 MPa (typical ICF spec is 25–30 MPa)
• ✓Horizontal and vertical rebar placed per engineer’s schedule
• ✓Wall thickness per OBC spans and load requirements
• ✓Stamped engineering drawings required for most ICF builds in Ontario

Energy Efficiency & SB-12 Compliance

Supplementary Standard SB-12 (Energy Efficiency for Housing) sets minimum effective RSI (thermal resistance) values for residential wall assemblies. Under the 2024 OBC, SB-12 has been reorganized into three chapters with prescriptive compliance packages by climate zone. Most Southern Ontario (including the GTA) falls in Climate Zone 6; Northern Ontario falls in Climate Zone 7.

For Climate Zone 6 (Toronto, Mississauga, Brampton, Markham, Simcoe County), the OBC requires minimum effective R-22 for exterior walls and R-20 for basement walls when paired with a 92%+ AFUE furnace. ICF wall assemblies provide continuous insulation on both faces of the concrete core with no thermal bridging at studs or fasteners.

A standard 6″ ICF wall (with approximately 2.5″ of EPS on each face) achieves an effective RSI of approximately 4.2 (R-24), comfortably exceeding the SB-12 Zone 6 requirements. An 8″ ICF core wall reaches effective RSI 5.3+ (R-30+), exceeding what wood-frame walls can achieve without continuous exterior insulation.

• ✓Continuous insulation on both faces of concrete core — no thermal bridging
• ✓Standard 6″ ICF: effective RSI ~4.2 (R-24)
• ✓8″ ICF core: effective RSI ~5.3+ (R-30+)
• ✓SB-12 energy compliance report required with permit application
• ✓For a detailed breakdown, see our heat loss assessment service

Ventilation, HRV/ERV & the MVDS Form

The 2024 OBC made a significant change to residential ventilation requirements. Section 9.32 now requires an HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator) as part of the principal whole-home ventilation strategy in essentially all new construction. The previous House Types I-IV classification has been eliminated.

Critically, the OBC now requires a Mechanical Ventilation Design Summary (MVDS) form to be filed with the building permit application. The MVDS must specify the selected HRV/ERV model, its ventilation capacity, its Sensible Recovery Efficiency (SRE) at -25°C from certified test data, and the SB-12 compliance path the home is following.

This change affects ICF builds the same way it affects wood-frame builds — you need a properly-specified HRV or ERV regardless of wall type. The good news for ICF: ICF’s natural airtightness (measured at 1.0–1.26 ACH50 in the RDH Labs study of 49 homes) means mechanical ventilation can be sized accurately without the over-sizing required to compensate for leaky wood-frame envelopes.

Fire Resistance & Thermal Barriers

The 2024 OBC requires that foamed plastic insulation — including the EPS foam used in ICF — be protected on the interior by a thermal barrier. In practice for residential construction, this means the interior face of ICF walls must be covered with a minimum 12.7mm (1/2″) drywall, or an equivalent listed thermal barrier material.

This is a standard interior finishing requirement and is met by normal drywall installation. On the exterior, ICF EPS is typically covered by cladding (brick, stucco, siding, stone) which satisfies exterior exposure requirements. The reinforced concrete core provides exceptional fire resistance — ICF walls typically achieve a 4-hour fire-resistance rating (ASTM E119), well exceeding the OBC minimums for typical residential and small commercial buildings.

Sound Transmission & OBC Acoustic Requirements

The 2024 OBC requires a minimum STC 50 for walls separating dwelling units in multi-unit residential. Wood-frame walls hit STC 50 only with specific double-stud or staggered-stud assemblies with acoustic insulation. A standard 6″ ICF wall measures STC 50–52 in lab testing (ASTM E90), and 8″ ICF reaches STC 52–55 — easily meeting code with the basic wall assembly.

For duplex, townhouse, and small commercial party-wall applications, ICF is often the simpler path to code-compliant acoustic separation — no special detailing required. For a complete breakdown of measured STC values and where soundproofing matters most, see our ICF soundproofing guide.

Building Permits for ICF in Ontario

All ICF construction in Ontario requires a building permit. The permit application process is the same as for any other construction method — you submit drawings, documentation, and pay the applicable fees to your local municipality.

ICF-specific documentation required for a typical 2024 OBC permit application:

• ✓Architectural drawings showing wall assemblies, opening details, and ICF system specification
• ✓Structural engineering drawings (stamped) — required for most ICF residential projects in Ontario
• ✓SB-12 energy compliance report demonstrating effective RSI values for the wall assembly
• ✓MVDS form (new requirement under 2024 OBC) for the HRV/ERV ventilation system
• ✓ICF manufacturer product data — all major brands (Nudura, Amvic, Element ICF, IntegraSpec, Fox Blocks, etc.) have third-party testing documentation
• ✓Site plan showing setbacks, grading, and drainage
• ✓Radon rough-in details (sub-floor depressurization) per harmonized NBC 2020 requirements

Inspections at Every Stage

ICF projects are inspected at the same stages as any concrete construction, plus the energy and ventilation verification steps required under the 2024 OBC. Here’s what to expect: