The National Building Code of Canada, and subsequently the British Columbia Building Code, (Building Code) generally require buildings to be provided with illuminated exit signs. While these codes provide considerable details about the pictograms associated with exit signs and how they are to be illuminated there is little discussion about visibility of exit signs other than being “visible upon approach to the exit”. Like many of the Acceptable Solutions in Division B of the Building Code this statement is not based on any technical merit as is wholly subjective. This can potentially create life safety issues during emergency evacuations.

CSA 22.2 No. 141 “Emergency Lighting Equipment” requires internally illuminated signs to be placed at intervals so that the maximum viewing distance is no more than 30.5 m, however this is not strictly a requirement in the Building Code. Further, no additional consideration is given to the overall size of the sign. Considering that the legibility of a sign is directly proportional to the size of the sign and the viewing distance, adjustments in sign size should be made based on the viewing distance.

Most international standards provide some guidance on the size of an exit sign with respect to the distance it is viewed at. For example, in New Zealand the compliance document F8/AS1 provides information about minimum viewing distances for both internally illuminated and externally illuminated/photoluminescent signs and exit sign pictogram height.

Acceptable Solutions and Verification Methods for New Zealand Building Code Clause F8

Further, viewing distances greater than 32 m, the minimum element height shall be determined in accordance with the following equation:

Minimum element height, mm = Maximum viewing distance, mm / 160

and rounded up to the nearest 50 mm.

In the United Kingdom, BS 5266 pt7 details exit sign heights as follows:

Internally Illuminated:

Maximum Viewing Distance, mm = 200 X panel height, mm

Externally Illuminated:

Maximum Viewing Distance, mm = 100 X panel height, mm

Although the Building Code does not specifically call out exit sign size, consideration should be given to the size of the sign and the respective viewing distance. This can aid in emergency wayfinding and promote for efficient evacuation.