Exploring the Building Code - Canopies

I had actually started and stopped writing the following article regarding canopies and exterior wall projections on several occasions. I first started it as a result of a response to a Linked-in post back in early 2019 and It’s been on my code “todo” list ever since. Back then I didn’t feel a sense of urgency and my interest waned. Recently, I had been considering taking up the subject matter anew with the start of the pandemic and the rise in interest in outdoor dining, specifically covered outdoor dining. When we saw a correction letter relating to the subject matter, it was clear that I could do additional research and write this article based on the efforts we made to clear up the correction item.

The model code defines the area of a building as the area included within surrounding exterior walls and including areas not provided with surrounding walls if the area is included within the horizontal projection of the roof or floor above. A similar definition is also provided for fire area, which is a bit more esoteric but the use of similar language is just as important. The reasoning for this is sound, what happens outside can make its way inside the building. If an occupied floor projects over an open exterior people occupying the floor above might not be aware of a fire started below until their means of egress is cut off. In the case of the horizontal projection of a roof, the concern is that the extension of the roof assembly creates a horizontal shaft that an exterior fire could use and make its way back into the building. 

Even though the intent and reasoning is clear the implementation is not. The code only talks about “The Roof” What is the roof? Is it any projection per 705.2 or canopy per 3105? The answer to the second question is no, the answer to the first however like the application of the code section can be muddy. The intent is that in an exterior application that the roof must be an extension of the roof of the building. The test I typically use when I am reviewing drawings is can the covering or roof element be removed and the exterior envelope of the building left intact? So for a typical canopy or wall projection the roof element must be hung from an exterior wall or over framed off another roof, and at a minimum if removed as in the case of over framing is the roof sheathing of the primary roof still in place or is the exterior wall in place such that only cosmetic repairs are all that’s needed. This interpretation is in keeping with both the definition of area, building and fire area which states first and foremost that these elements terminate at an exterior wall.

Using two similar building as anexample, but constructed in two different ways should help clarify the intent of the code. Picture a pair of restaurants with what appear to be identical covered exterior patios supported by columns and a roof of some nature attached back to the buildings. In the first restaurant the exterior wall stops at the bottom of a roof or floor truss which extends out and over the patio. This would be an example where this is an extension of the roof of the building as there is no way to remove the patio covering without also affecting the building. In the second restaurant the exterior wall continues up and through the height of the patio roof. The structure for the patio roof maybe hung from the exterior wall, but the structure supporting the covering is not shared with the building. In the first example a fire can start outside the building and make its way back into the building, in the second example the code provides guidelines on projections and canopies to understand how the projection would be built but the area beneath the projection or canopy would not be included in either the fire or building area. This is important when it comes to the code requirement for sprinklers. In the first building if the building was sprinklered the exterior patio would be part of the building and need to be sprinklered as well (Unless you use some other exception in NFPA 13) in the second example the patio is not part of the building and there is no consideration for it to have sprinklers installed. Another way to look at this is per 903.2.1.2-2 if a restaurant assembly occupancy has an occupant load over 100 it must be sprinklered. If our first building had an interior occupant load of 80 and an outdoor covered patio with an occupant load of 30, the building would need to be sprinklered as the definition of fire area which normally stops at an exterior wall would need to include the area within the horizontal projection of the roof. Our second building because the exterior walls extend and separate the roof covering the patio from the interior of the building would not trigger the need for sprinklers. This was confirmed with the ICC in a written staff code opinion. 

There is one caveat to this scenario if the exterior patio’s has a means of egress through the building, the occupant load is cumulative, and this would raise the occupant load of the building over 100. This caveat has nothing todo with roofs but with egress. When designing a means of egress the occupant load must include any exterior spaces that maybe egressing through the building for the sizing and requirements of the means of egress, including the need for sprinklers.