# Ontario Soundproofing 2026: STC and IIC Ratings, Secondary Suite Requirements and Assembly Options

**URL:** <https://home.renovation.reviews/t/ontario-soundproofing-2026-stc-and-iic-ratings-secondary-suite-requirements-and-assembly-options/46929>\
**Category:** Ontario\
**Created:** [April 26, 2026, 7:30pm UTC](https://home.renovation.reviews/t/ontario-soundproofing-2026-stc-and-iic-ratings-secondary-suite-requirements-and-assembly-options/46929 "2026-04-26T19:30:25Z")\
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**Author:** ![system](https://home.renovation.reviews/user_avatar/home.renovation.reviews/system/32/77_2.png) [@system](https://home.renovation.reviews/u/system)\
**Post date:** [April 26, 2026, 7:30pm UTC](https://home.renovation.reviews/t/ontario-soundproofing-2026-stc-and-iic-ratings-secondary-suite-requirements-and-assembly-options/46929/1 "2026-04-26T19:30:25Z")

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Soundproofing is critical for legal secondary suites in Ontario and increasingly for open-plan main floor conversions. Here’s the technical breakdown.

**Key metrics:**

- **STC (Sound Transmission Class):** Airborne sound. OBC minimum for suite separations: STC 43. Target for comfortable living: STC 50-55.
- **IIC (Impact Insulation Class):** Footstep/impact sound. OBC minimum: IIC 43.

**Assembly options for basement suite ceiling (also main floor):**

| Assembly | Approx STC | Approx IIC |
| --- | --- | --- |
| Single drywall on wood joists | 33 | 28 |
| Drywall + acoustic insulation | 39 | 35 |
| Resilient channel + double drywall + acoustic insulation | 50-55 | 45-50 |
| Sound isolation clips + double drywall + floating floor above | 55-60 | 52-58 |

**Party wall options:**

- Resilient channel on existing studs + second drywall layer: STC 45-50
- Staggered-stud on single plate: STC 50-55
- Double-stud (fully decoupled): STC 60-65, sacrifices 4-6" floor space

**Flanking paths are the most common compliance failure** – sound routes around well-built assemblies through wall plates and framing. Perimeter details are as important as the assembly itself.

**GTA costs (2026):**

- Resilient channel ceiling + double drywall (per 100 sq ft): $800-$1,400
- Complete suite acoustic package (800 sq ft basement): $12,000-$25,000

_Secondary suite and soundproofing questions at [home.renovation.reviews](https://home.renovation.reviews)_