// BC Step Code Timeline
BC Step Code 4 Requirements
Key takeaway: Step 4 is expected in 2027. The target is 1.5 ACH50: 40% tighter than Step 3. FortisBC rebates up to $15,000 offset most of the incremental cost. Builders who start now are ahead.
BC Step Code 4 Requirements at a Glance
BC Step Code 4 is performance-based: you hit three measured targets verified through energy modelling and an on-site blower door test, rather than following a fixed parts list. For a Part 9 residential build, these are the numbers that define compliance:
| Requirement | Step 4 Target | Step 3 (for comparison) | How it’s verified |
|---|---|---|---|
| Airtightness (ACH50) | ≤ 1.5 ACH@50Pa | ≤ 2.5 ACH@50Pa | Blower door test |
| TEDI — Thermal Energy Demand Intensity (CZ5) | ~35–45 kWh/m²/yr | ~30 kWh/m²/yr | HOT2000 energy model |
| MEUI — Mechanical Energy Use Intensity | Climate-zone dependent | Higher allowance | HOT2000 energy model |
| Expected effective date | 2027 (provincial minimum) | Mandatory since 2023 | BC Building Code |
The exact TEDI and MEUI limits tighten with climate zone — a CZ6 mountain build (Revelstoke, Big White) carries a stricter envelope demand than the CZ5 Okanagan valley floor. See ACH50 targets by step and the Step Code by municipality table for how requirements shift by location.
What Each Step 4 Requirement Means
Airtightness (ACH50): 1.5 air changes per hour at 50 Pascals or less. Down from 2.5 at Step 3. This is where most builders struggle, and where air sealing technology makes the biggest difference.
TEDI (Thermal Energy Demand Intensity): Varies by climate zone. In CZ5 (Okanagan, HDD ~3700): roughly 35 to 45 kWh/m2/year. TEDI is the heating-only metric, so it forces a genuinely better envelope rather than letting better mechanicals paper over a leaky shell.
MEUI (Mechanical Energy Use Intensity): Total mechanical energy use. Equipment selection (heat pumps, HRVs) is critical here.
What Changes from Step 3
Airtightness gets 40% tighter. At Step 3, careful manual sealing usually works. At Step 4, conventional tape-and-caulk methods become unreliable. Many builders incorporate aerosol-based sealing that targets a specific ACH number.
Envelope performance improves. Higher effective R-values, better window U-values, more attention to thermal bridging. Typical: 2x6 walls with continuous exterior insulation.
Heat pumps become standard. Furnaces as primary heat sources make MEUI numbers very hard to hit. The FortisBC hybrid pathway (heat pump + gas furnace backup) qualifies for the highest rebate tier.
Energy advisor involvement increases. Getting involved at design stage saves thousands by optimizing envelope vs. equipment spending.
What It Costs
For a 2,000 sq ft home in the Okanagan: $8,000 to $20,000 over Step 3. Main drivers: windows ($3,000 to $8,000), insulation ($2,000 to $5,000), HVAC ($2,000 to $6,000), air sealing ($2,000 to $4,000).
FortisBC rebates up to $15,000 for Step 4. Combined with CleanBC, 50% to 80% offset is realistic. See our cost breakdown and rebate calculator.
How to Hit 1.5 ACH50
Start with air barrier design. Decide primary air barrier location before construction. Detail every penetration and transition on drawings.
Mid-construction blower door test. Optional by code, mandatory in practice at Step 4. Kelowna offers a $325 rebate. Fix leaks while the barrier is accessible. See our pre-drywall guide.
Seal systematically. Bottom plates, window rough openings, electrical penetrations, plumbing, attic transitions. These are where aerosol sealing excels. See our full guide on how to achieve Step Code 4 airtightness for method-by-method results.
The 2027 Timeline
BC has signaled Step 4 as the provincial minimum for Part 9 buildings in 2027. The specific Ministerial Order has not been signed as of early 2026, but the direction is clear. Some Metro Vancouver municipalities already require Step 4 or higher.
Municipality Requirements
Check your area: Kelowna | West Kelowna | Vernon | Penticton | Lake Country | Kamloops | all BC municipalities
For a phase-by-phase approach, see our Step Code 4 checklist. For the full 5-stage Okanagan wood-frame build sequence, see how to achieve 1.5 ACH50 in wood frame construction. For real project data from 100+ Okanagan seals (best result: 0.24 ACH50, 92% Step 4 hit rate), see aerobarrier case studies.