# Permits and fire separation

Lesson 1 of [Review a collector garage specification](https://luxurygaragebuilders.fyi/academy/review-a-collector-garage-specification.md), 18 minutes.

Codes change by country, state and town. Always confirm the rules with your local building department or planning authority before you build.

## United States: the IRC

ALI reports that the International Residential Code (IRC) is in use or adopted in 49 US states. Many towns amend it. A Washington State tip sheet gives these 2021 IRC rules for an attached garage:

- **Walls and attic next to the house (Table R302.6).** At least 1/2-inch gypsum board, or equivalent, on the garage side.
- **Habitable rooms above the garage.** At least 5/8-inch Type X gypsum board, or equivalent.
- **Doors into the house (R302.5.1).** Solid wood, or solid or honeycomb-core steel, at least 1-3/8 inches thick, or a 20-minute fire-rated door. The door must self-close and self-latch. It must not open into a sleeping room.
- **Ducts (R302.5.2).** Ducts in the garage must be at least No. 26 gauge sheet metal, with no openings into the garage.

**Floor.** Garage floors must be an approved noncombustible material. The parking area must slope so that liquids move to a drain or toward the main vehicle door. The code gives no minimum slope figure, so ask your designer.

## England

Garages count as outbuildings. The Planning Portal says that many garages need no planning permission, within the permitted development limits. These limits include:

- not forward of the principal elevation;
- single storey, with eaves no higher than 2.5 m;
- overall height no more than 4 m with a dual-pitched roof, or 3 m with any other roof;
- no more than 2.5 m high within 2 m of a boundary.

A listed building needs planning permission for any outbuilding. Designated land, such as a conservation area, has stricter rules. An attached garage normally needs building regulations approval.

## Canada and Australia

Ontario requires a building permit for any new building over ten square metres. In New South Wales, a garage can be complying development on some residential lots, within limits on lot size, height and door width. If a garage does not fit those limits, contact your local council.

## Sources

Each page was accessed on 2026-10-29.

- [MyBuildingPermit.com, Construction Tip Sheet 06: Residential Garage Separation (2021 IRC)](https://mybuildingpermit.com/sites/default/files/TS_06_Residential_Garage_Separation_2021_IRC_Final_0.pdf)
- [InterNACHI, Attached Garage Fire Containment](https://www.nachi.org/attached-garage-fire-hazards.htm)
- [ALI, 2024 IRC Chapter 3: Automotive Lift Requirements](https://www.autolift.org/automotive-lift-certification/code-enforcement/2024-irc-chapter-3-automotive-lift-requirements/)
- [Planning Portal, Smart Search: Garages](https://interactive.planningportal.co.uk/smart-search-house-elements/garages)
- [Planning Portal, Planning Permission: Outbuildings](https://www.planningportal.co.uk/permission/common-projects/outbuildings/planning-permission)
- [Ontario, Building permits](https://www.ontario.ca/document/citizens-guide-land-use-planning/building-permits)
- [NSW Planning, Carports and garages fact sheet](https://www.planning.nsw.gov.au/sites/default/files/2023-02/carports-and-garages-rules-for-exempt-development.pdf)
- [LuxuryGarageBuilders, Garage Permits and Building Codes](https://luxurygaragebuilders.fyi/guides/garage-permits-and-building-codes)

Also on the [web page](https://luxurygaragebuilders.fyi/academy/review-a-collector-garage-specification/permits-and-fire-separation).