6.1.6 Architectural Oblivion: Design Briefs of Denial

“Given that government agencies around the world have focused on reducing fire hazards, much less attention has been paid to the ways in which vulnerable WUI developments might have been designed from the start” Moritz et al, 2014.

As in the adjacent wildlands, fire’s behaviour at the urban interface is determined by the site specifics. Thus, as discussed earlier, wherein urban materiality mirrors that of the wildland, so too does the qualitative nature of a fire within the setting, and vice versa: the greater the variance in the biochemical and topographical make-up, the less the commonalities between the two. The fire season lengthening, the number of fire weather periods therein increasing, and the volume of both natural and human ignitions likewise, two sides of a WUI fire triangle are complete. Turning to the third, fuel, the now many structures of the territory constitute a highly flammable abundance thereof.

The primary initial cause of structural ignition within the WUI being firebrands and heat flux (Moritz et al, 2014; Mell et al, 2010; CALFIRE, 2007), fire commonly takes hold through ignition of combustible decking, fences, outbuildings, and roofs and/or roof coverings (Maranghides et al, 2015; Champ et al, 2013). Quantifying the extent to which anthropogenic augmentation of the landscape impacts upon the probability of a residence being lost to fire, for every additional outbuilding within 40m the odds of its ignition are predicted to increase by 3% (Gibbons et al, 2012). However, homes with wooden roofs are especially vulnerable to ignition. One study found that whereupon a property with a wooden roof ignites its odds of survival are just 19%, compared to 70% in the instance that a property’s roof is primarily constructed of non-combustible materials (Gill et al, 2013). As with outbuildings, in closely spaced WUI communities, fire spread from house-to-house is commonplace during fires, and especially during extreme fire weather (Moritz et al, 2014), with higher density housing fairing worst (Mell et al, 2010). At times, the rate of spread is so rapid that, “even when first responders are at peak deployment of resources” they cannot keep pace, which in the instance of the Waldo Canyon Fire was an ignition rate of 1.3 structures per minute (Maranghides et al, 2015, p.5).

Compounding the “structure ignition problem”, as Mell et al coined it (2010, p.238), many commonly used building material tests “are not representative of WUI fire conditions” (Ibid. p. 242), the matter thereof in part a reflection of the complexities of fire’s behaviour in the environment, and of the fact that “characterising” that behaviour, together with quantification of structural response, and, more generally, assessing the risk of fire within the WUI is in its “infancy” (Maranghides et al, 2015, p.7). Furthermore, even in the event that new materials, policies, and other fire- mitigation innovations come into practice, for so long as the WUI is expanding, older housing stock [i.e. legacy building materialities and building topologies] will likely face higher risk of ignition during a period in which fire-fighting resources are becoming ever more stretched (Mann et al, 2013). By means of quantifying the scale of the challenge, when the Witch Fire of 2007 swept through the ‘fire hardened homes’ of The Trails development in San Diego, of the 245 that were within the fire perimeter 74 were destroyed, and a further 16 damaged (Maranghides and Mell, 2011, p. 379), of which, true to scientific probability form, 2/3 were ignited by indirect ember and firebrand attack (Ibid).

While, regardless of their origin, the structural ignition threat posed by burning embers blown aloft is relatively equal, and the fact that, statistically, roofs are amongst the foremost likely structural elements to ignite, recent recommendations for changes to the California Building Codes for the WUI accommodate for several classes of fire-resistance, of which the highest, Class A, is assigned to assemblies “effective against severe fire test exposure”, and extending across mineral-based assemblages including brick, concrete and copper shingles. Thereafter, Class B is assigned to assemblies “effective against moderate fire test exposure”. In turn, Class C is assigned to assemblies “effective against light fire-test exposure”. Thereafter, classes include the ambiguous sounding ‘Nonclassified roofing’, which is described as appropriate for “approved material that is not listed in Class A, B, or C roof covering”; Fire-retardant-treated wood shingles and shakes, building integrated and panelled or modular photovoltaic systems, and roof garden and landscaped roofs, amongst others (CA Building Codes, 2016). Given, both climate theory and modelling strongly suggest that extreme fire weather is the region’s ‘new norm’, one might argue there not room for roofing assemblies as meet not Class A, or standards akin thereto.

However, that mineral-based roofing assemblies are being assigned the highest fire- safety classification is but one example of how contemporary WUI building codes as relate to materials are tending to migrate towards thinking that has been expressed in vernacular architectures within some fire-prone regions for centuries. For example, the terracotta and clay roof tiling found in several traditional Chinese and Japanese building styles help prevent against the ignition of their wooden structures and walls. Another way in which architectural thinking, practice, and policy as relates to the WUI echoes ancient Eastern protocol is the integration of means by which to ground lightening, of which early variants include ornate dragon heads with iron-wire tongues that connected to ground-level (Fan, 2001), and which today incarnate in the form of rods, downconductors, bonding, and shielding. Yet, as discussed earlier, such is the scale of scientific-illiteracy within some contemporary built environment communities as for many researchers and practitioners to think it appropriate to place trees – they being entities that emit electrical signals that contribute to the local electric field, and thus, during a dry storm can become lightning conductors – atop of roofs.

“Too often people put themselves at risk by sheltering under a tree during a thunderstorm” Elsom and Webb, 2014, p.223

In addition to rooftop ‘forests’, the wider urban fabric remains vulnerable to ignition by lightening, for “the marketplace abounds with exaggerated claims of product perfection. Frequently referenced codes and installation standards are incomplete, out- dated and promulgated by commercial interests” (Kithil, 2018) they being words which, many still reeling from the Grenfell Tower Fire, make for disturbing reading.

Additional attributes of Eastern vernacular architectures that embed a degree of fire- resistance include the topography of triangular roofs, together with deep overhangs and eves, the slope of the former helping to displace embers and burning debris that falls from above, the latter reducing the probability of burning firebrands entering a building. Again, ancient architectural precedent pre-empted present-day developments: firebrands and embers that have either lodged in exterior building parts [i.e. guttering], or have entered an interior via vents or windows, is a primary cause of ignition of buildings during wildfires (Ramsay et al, 1996; Gill, 2005; Blanchi and Leonard, 2008; Gill et al, 2013). As with Native American architectures, myth is as much a part of Eastern vernacular architectures as their structural members, wherein, what amount to building codes were, and in some regions continue, to be transferred through oral not written means. As in linguistics, in order to, metaphorically speaking, read these codes, one needs familiarity with the language system in which they are ‘written’. As discussed above, the dimensions of ancient communications systems extended beyond two, instead operating on multiple time and spatial scales, both within and beyond the real world. In other words, ancient peoples perceived of augmented realities, including, but not limited to the application thereof to solving complex architectural problems. In Chinese vernacular architecture this is expressed through features including building orientation, dimensions, floor plan, materiality, motifs, colours, and rebuses [pictorial codification] that reflect metaphysical concepts including the auspicious powers as were attributed to the mythological creature Chiwen [Hornless-dragon mouth] [Fig. 61], which included protecting against fire, flood, and typhoon, and summoning rainfall.

A testament to the capacity of Eastern vernacular architectures to endure fire, amongst other hazards, is the Buddhist temple precinct of Horyu-ji, which completed in 607AD, and partially destroyed in a fire of 670AD, nonetheless houses some of the oldest wooden buildings worldwide. But, in the boundary-blurring domain of both the ancient and contemporary wildland urban interface, anthropogenic augmentation of the threat posed by wildfire extends beyond architecture, and into the [cultivated] landscape.

>Continue to Chapter 6.1.7 here.

The thesis is also available in PDF format, downloadable in several parts on Academia and Researchgate.

Note that figures have been removed from the digital version hosted on this site, but are included in the PDFs available at the links above.

Citation: Sterry, M. L., (2018) Panarchistic Architecture: Building Wildland-Urban Interface Resilience to Wildfire through Design Thinking, Practice and Building Codes Modelled on Ecological Systems Theory. PhD Thesis, Advanced Virtual and Technological Architecture Research [AVATAR] group, University of Greenwich, London.