These rules are laid out in Chapter 7A of the California Building Code. Currently, at least in Sonoma County, this means all new structures must be “built with exterior construction that will minimize the impact on life and property and help structure to resist the intrusion of flames and burning embers projected by a wildland fire and contributes to a reduction of losses.”
Contractors have responded by implementing several different tools and products to “harden” homes to fire. Negri’s company has turned to tempered glass windows, metal roofs and fiber cement siding. One particular project, a spacious new home under construction in downtown Healdsburg, features fiber cement siding.
Other firms have experimented with rammed earth construction, as well as Insulated Concrete Form (ICF) products such as Rastra blocks, which are made with foam, and Faswall blocks, which are made with wood chips and particles.
While many of these products make homes more resistant to fire, they also are more expensive.
Prices for ICF and fiber cement products can run as much as 20% higher than current industry standards. At last check, a standard wood-frame and stucco wall cost about $12 per foot, while a rammed earth wall usually costs about $100 per foot.