Spatial separation calculator

NBC 2015

The concept of spatial separation is to ensure that buildings are distanced far apart enough so that fire is unlikely to spread from one building to another. The National Building Code of Canada (NBC 2015), Ontario Building Code (OBC 2017), Manitoba Building Code (MBC 2010), British Columbia Building Code (BCBC 2018), and Alberta Building Code (ABC 2014) include tables from which the percentage of unprotected openings that are permitted in a building or compartment are calculated. Construction requirements for the exposing building face are prescribed based on the permitted area of unprotected openings.

Subsection 3.2.3 prescribes percentage limits for unprotected openings for buildings classified under Part 3 of the Building Code. Tables 3.2.3.1.B and 3.2.3.1.C provide values for unsprinklered Part 3 buildings, and Tables 3.2.3.1.D and 3.2.3.1.E provide values for sprinklered buildings.

Article 3.2.3.7 prescribes construction requirements for the exposing building face based on the permitted unprotected openings calculated from the applicable table.

Area of unprotected openings permitted is based on two factors:

1. Area of the exposing building face of the fire compartment.

2. Limiting distance measured to the property line, designated imaginary line, or centerline of a street.

Where the limiting distance or exposing building face area is between values on the respective table, the calculator will interpolate between the values. Simply enter the width, height and limiting distance of the fire compartment and the calculator will output the permitted unprotected openings and construction requirements derived from Table 3.2.3.7.