Free Tool
Firewall and Party Wall Fire Rating Checker
See the fire-resistance rating and sound rating the Ontario Building Code asks for in a party wall, a wall between suites, a secondary suite or a garage wall.
Firewall and Party Wall Fire Rating Checker
Result
We frame firewalls and party walls for townhouses, duplexes, triplexes and stacked units across Ontario, built to the rated assemblies on your drawings.
Get a quote for party wall framingPreliminary planning only. This tool does not replace the drawings. The designer or engineer of record and the building permit set govern every size, span and detail.
We frame firewalls and party walls for townhouses, duplexes, triplexes and stacked units across Ontario, built to the rated assemblies on your drawings. Firewall and party wall framing, Townhouse framing. Request a free quote.
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Where the numbers come from
- Party walls and firewalls. Part 9, Articles 9.10.11.1. to 9.10.11.4., Firewalls. (source)
- Suites. Articles 9.10.9.15. and 9.10.9.16., Separation of Suites and of Residential Suites; Table 9.10.8.1. and Article 9.10.9.4. for floors. (source)
- Garages. Article 9.10.9.18., Separation of Storage Garages. (source)
- Firewall construction. Part 3, Articles 3.1.10.2. to 3.1.10.5., Rating of Firewalls, Continuity, Parapets and Maximum Openings. (source)
- Sound. Articles 9.11.1.1. to 9.11.1.4., Protection from Airborne Noise. (source)
- Assemblies. SB-3, Fire and Sound Resistance Tables, Tables 1 and 2. (source)
Worked example
Two townhouse units share a wall on a property line and no unit sits above another. Article 9.10.11.1. makes the wall a firewall, and Article 9.10.11.2. allows a fire separation of not less than 1 h instead, continuous from the footings to the underside of the roof deck. The assembly also has to give STC 50 or more with flanking construction to Article 9.11.1.4. If a unit sat above another, the 1 h shortcut would not apply and the wall would be a 2 h noncombustible firewall to Part 3.
Ratings at a glance
| Wall | Fire rating | Section |
|---|---|---|
| Party wall on a property line, no unit above another | 1 h fire separation (or firewall) | 9.10.11.1., 9.10.11.2. |
| Party wall on a property line, stacked units | Firewall, 2 h noncombustible | 9.10.11.1., 3.1.10.2. |
| Suites in one building | 45 min, or 1 h for a unit of 2 or more storeys | 9.10.9.16. |
| Floor between stacked units | 45 min | Table 9.10.8.1., 9.10.9.4. |
| Garage to garage across a property line | 45 min | 9.10.11.4. |
| Dwelling unit to other spaces: sound | STC 50 (or ASTC 47) | 9.11.1.1. |
Last checked 2026-11-09 against the 2024 Ontario Building Code (O. Reg. 163/24) compendium and SB-1 as published on ontario.ca.
This tool is for preliminary planning. The designer or engineer of record and the building permit set govern.
Frequently asked questions
What is the difference between a firewall and a fire separation?
A firewall divides a building into separate buildings for fire purposes and is built to Part 3: not less than 2 h, noncombustible, normally masonry or concrete, running from the ground through every storey (Articles 3.1.10.2. and 3.1.10.3.). A fire separation is a rated wall or floor assembly inside one building, with a lower rating and no parapet rule.
Does a townhouse party wall have to be a firewall?
A party wall on a property line is a firewall (Article 9.10.11.1.). For a residential building, Article 9.10.11.2. lets it be a fire separation of not less than 1 h where it separates two dwelling units and no dwelling unit is above another. It must give continuous protection from the top of the footings to the underside of the roof deck, and any space above it is tightly filled with mineral wool or noncombustible material.
What sound rating is needed between dwelling units?
A dwelling unit is separated from every other space where noise may be generated by an assembly and adjoining construction with an apparent sound transmission class (ASTC) of 47 or more, or by an assembly with an STC of 50 or more plus flanking construction that meets Article 9.11.1.4. (Article 9.11.1.1.). Compliance is shown by test or by an assembly from Table 1 or 2 of SB-3 (Article 9.11.1.3.).
What about a house with a secondary suite?
The 45 min rating can be replaced by a continuous smoke-tight barrier of 15.9 mm Type X gypsum board on both sides of the walls and on the underside of the floor-ceiling framing, and the rating may be waived where the house is sprinklered (Article 9.10.9.16.(4) and (5)).
What is out of scope?
Buildings larger than Part 9 housing and small buildings, other occupancies, wall assembly listings, penetrations, closures and parapet details. Part 3 and the designer of record apply. Your municipality confirms the assembly.
Is this a quote?
No. It is a planning tool. Contact us with your plans and we will arrange a free site visit.
For the other framing rules in a townhouse project, see Townhouse Framing.
Related: Firewall and party wall framing, Townhouse framing, Duplex framing.
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Want a framing quote?
We frame firewalls and party walls for townhouses, duplexes, triplexes and stacked units across Ontario, built to the rated assemblies on your drawings.
Send your plans, photos or a description of the project. We will arrange a free site visit and return an itemized quote.
