After watching the news the other night pertaining to a fire in which the vinyl siding caught fire on one house and then caused the adjacent home, which also had vinyl siding, to also catch fire I was reminder of the Grenfell Tower Fire in London England. (That fire was caused because the exterior finish was inappropriate for the use.)
Neighbours used garden hoses to put out the vinyl siding fires on both homes well before fire department arrived. I noted the exposed plywood sheathing below the siding shown on TV. If left to burn the exterior walls of both homes would probably not have survived.
These were fairly new homes and I cannot comment on the distance between them; however the fire spread from one to the other as seen on TV.
In many older areas of the city homes are constructed with much less than 1.2 M between structures and they are finished with vinyl siding (or other combustible) materials. There are other combustible materials used on new homes throughout the province.
My question is this: Is this a result of inadequate building code requirements, or that authorities do not enforce these requirements?
4 Responses
The first National Building Code wasn’t published until 1941. Before that it was a hodgepodge of local requirements. The spatial separation requirements of the NBC were revised after the St. Lawrence Burns in 1958. There are various documents related to the St. Lawrence Burns and spatial separation calculations by McGuire, Leir and Gosselin that are available online. Keith Calder also has a presentation that discusses the topic.
UL Firefighter Safety Research Institute has a great course (free), on exterior fires that extend to the attic. It’s worthwhile reviewing the course, at the least the earlier portion of the course that deals with their testing of exterior walls and the roles of each: cladding, sheathing and insulation play with respect to various size fires. They also look at eave construction. The temperature on the inside face of the drywall was surprising. The course continues with firefighting tactics in dealing with exterior fires and attic fires.
https://ulfirefightersafety.org/research-projects/residential-attic-fire-mitigation-tactics-and-exterior-fire-spread-hazards.html
Regarding the current situations. I don’t think there is full understanding of the spatial separation requirements from both sides, Architects and plan reviewers. A few problems that I’ve encountered are builders changing siding after the plans have been approved. Also, with all the renovations over the past few years, homeowners and contractors not understanding that zero-lot lines requirements. In addition, new windows being installed in the exposing building face in existing buildings with no regarding for limiting distance and area of unprotected opening requirements.
As a CRBO AHJ it has been my experience that the spatial separation requirements are not being correctly interpreted, used or enforced by many. This is precisely why I spent 5 years writing a Spatial separation program and recently posted it on my LinkedIn page for free access to it.
Thank you Darrell! For anyone reading, here is the link to the post Darrell is referring to: https://www.linkedin.com/posts/darrell-saby-820436b8_spatial-separation-program-2-errors-were-activity-6740702771777024000-ufVt
Actually this is the correct link.
https://1drv.ms/u/s!AkGDmZGAARthkT8foj_gYoOtHlJd?e=OaZzmy