Bushfires are unpredictable. They are wild, which is why I like the American term wildfire. Not even computational fluid dynamics can predictively model them. How bushfires start, develop, spread, change direction and intensify is all chaos theory, only understandable in hindsight. They are capricious, incalculable, variable and erratic.

But so is designing for them. Every step in the process seems the same: capricious, incalculable, variable and erratic. It’s much more difficult to design for bushfires than designing to resist building fires, floods or even earthquakes.

Making houses that can withstand bushfires seems to me to be just as chaotic as the bushfires themselves. For whatever reason, the regulations seem part science, part art, and a whole lot of guessing.

In my experience two bushfire consultants can come up with quite different assessments of risk (via a ‘bushfire attack level’ or BAL) for the same site. And that seems understandable, logical even, given the vicissitudes of an unpredictable cause, variety of vegetation, possible wind directions, temperatures, and changes over time, particularly in climate.

The same can be said for choosing materials against the BAL. There are few accepted and codified performance levels of materials, which makes designing for materiality particularly fraught. Each design has to be calculated anew and argued individually. Then there is the issue of upgrading existing non-compliant buildings versus the possibly overcompensated buildings.

In 2020 I presented an argument for better bushfire design in a segment on ‘The Drum’ (remember that ABC programme?). I discussed designing to protect both life and property. It followed previous writings in A&D about designing for bushfires, community responses, and indigenous approaches to bush management.

In brief, my argument remains simple: you cannot design a house for enjoying life in the bush, for years on end, that will also withstand the unknowable arrival, if ever, of a bushfire. Untold wealth can be spent on a window-shuttered concrete, brick and steel fortress, but will it be good to live in before the bushfire? or after a bushfire has left it standing in a moonscape, stinking of smoke?

Designing buildings to withstand bushfires is not the answer. Architects need to get over it.

The alternative is threefold. Manage the bushfire risk by listening to the indigenous methods. Protect the building in a bushfire by drenching it with water sprays. And thirdly protect the residents in either a local bushfire shelter or a community safe zone.

This is what a water spray system looks like. Water drenching along the ridges and at the vulnerable parts of the house, relying on water stored in tanks with automatic diesel pumps through manifolds for controlled pressure and dispersion.

This is what a refuge bunker, or shelter on an individual property, looks like. A concrete enclosure with vegetation over it, a smoke-proof door that can’t be blocked by falling debris, and that has a source for a fresh air supply.

Both are researched and confirmed to work and, critically, reduce risk. But those design ideas are not codified to a compliance level as acceptable solutions to meet council approval. Nor make the building (and its occupants) have lower insurance or any insurance.

Having pushed so much suburbia into our well-oiled, volatile eucalypt bush, we are the most vulnerable nation on earth to bushfire. Yet the irony is a corollary: we have the least codified solutions to address it. The urgent design problem is not the building itself but two externalities.

Cross-Sections are Friday musings from Tone Wheeler, formerly of Tone on Tuesday. Amateurs draw plans; professionals draw sections – never at cross purposes.

Tone Wheeler

Let’s connect!