Walker Consultants Building Envelope Services

2024 IECC Updates

The 2024 International Energy Conservation Code (IECC) raises expectations for verified enclosure performance. Early engagement, proactive testing, and independent oversight are essential to minimizing risk and achieving predictable outcomes. Walker Consultants helps project teams meet these requirements with clarity and confidence.

What Changed

The code now expects proof.

The 2024 IECC significantly changes how building enclosure performance is demonstrated. For owners and project teams, that can affect cost, schedule, documentation, and occupancy when issues are found late.

Whole-building testing becomes mandatory

Air leakage testing is no longer just an optional alternative pathway for many commercial projects.

Lower leakage limits raise the bar

Tighter allowable limits require greater precision across enclosure design, construction, and field execution.

Failures trigger diagnostics

When initial results exceed allowable thresholds, diagnostic testing is required to identify performance gaps.

Corrections mean retesting

Corrective work can require mandatory retesting, adding pressure to schedule, closeout, and occupancy planning.

Documentation matters more

Expanded documentation and third-party verification make early coordination and clean records more important.

2024 IECC

Air leakage performance requirements

Compare how current and recent standards set maximum air leakage limits. Lower numbers mean tighter performance expectations.

IECC-C 2024 0.35

cfm/ft² @75 Pa

Lowest shown 0.08

Washington State shows the most aggressive value in this comparison.

1. Start with climate zone

2BNo air barrier required.

Climate zones other than 2BContinue to occupancy.

2. If occupancy is Group R or I

3C and 5CComply using materials or assemblies provisions + verification.

0, 1, 2A, 2C, 3A, 3B, 4, 5A, 5B, 6, 7, 8Building / building portion testing by Section 402.5.2.

3. If occupancy is other than Group R or I

3B, 3C and 5CComply using materials or assemblies provisions + verification.

0B, 1, 2A, 4B and 4C> 5000 sf: materials / assemblies + verification. </= 5000 sf: Section 402.5.3 testing.

0A, 3A and 5B> 50,000 sf: Section 402.5.3 testing. >5000 but <50,000 sf: materials / assemblies + verification. </= 5000 sf: Section 402.5.3 testing.

0C, 2C, 4A, 5A, 6, 7, 8Building / building portion testing by Section 402.5.3.