Sustainability Blog Entries — Allen Construction

Resilience in our Houses

Between 1955 and 1965 about 18 natural disasters occurred in the US annually. This decade, starting in 2010, we are averaging about 110 nationally declared disasters a year- roughly 2 per week. In the past, building codes were developed from historical data, but now State and Federal agencies are pushing communities to use predictive climate models to address more appropriately what’s coming.

Resilience is defined as “the intentional design of buildings, landscapes, communities and regions in response to vulnerabilities to disasters and disruptions to normal life.”

The local environment always plays a critical role in determining what makes a building resilient, or not. In other words, resilient design is always locally specific. Tapping into historic vernacular architecture, as well as local wisdom, knowledge and experience, often prompts strategies enabling buildings and occupants to better survive disasters. The big natural challenges we face in our region are droughts, wildfires, landslides, debris flows, intense precipitation, flooding, earthquakes and maybe even tsunamis. Resilience planning “is not about keeping people comfortable; it’s about keeping them alive” says Alex Wilson, President of the Resilient Design Institute. Preparedness includes planning for potable water, food, first aid, news and communication, toilet needs and getting around, probably without a car.

The 3 most important areas to focus on are:

Creating livable conditions for post-disaster. That means making your house (and surrounding space) wildfire resistant, constructing it to be seismically strong but flexible, and incorporating passive solar heating, cooling and natural ventilation. It is also important to provide protection from heavy rains with suitable roof overhangs, drainable planes behind siding, break-away panels, if in a flood plain, and infiltration swales and catch basins near the house.

Providing for back-up power. Evolve your home to be all electric with photovoltaic panels. Provide back-up power/storage for key electrical circuits in your home: refrigerator, cooking (if electric-magnetic induction), media, phone charging, electric car/bicycle, and a few lights. Avoid diesel generators. Battery back-up is increasingly affordable and reliable.

Accessing potable water. Develop a water supply, perhaps using rainwater collection, which can be filtered/purified with hand equipment to make it drinkable-safe. There are good filters pumps and ultraviolet portable treatment equipment available that were developed for wilderness trekking.

Doing all one can to stop, and even reverse, the climate crisis needs to be our top priority, but we also need to prepare for the disasters already arriving.

No home is entirely protected against wildfire. Most have at least a few weaknesses, a few materials or openings that make them vulnerable to flying embers or to the intense heat of wildland firestorms.

Reducing this risk channels attention to a few fronts. Creating a 30’-50’ “fuel free” zone around a dwelling is mandatory: key steps to implementing this strategy are pruning up and thinning out trees; changing decks, trellises, fences, patio furniture and other flammable outbuildings to non-combustible materials; and removing all plant dead wood, wood piles and other easily ignitable materials. Stone, tile or concrete patios, metal or masonry fences, tube steel trellises and cementitious sheds near the house are worthy choices.

Shifting attention to the house, avoid wood or vinyl siding (susceptible to melting in high heat). Fiber-cement siding is a good choice, preferably with tongue-and-groove rather than shiplap joints. Stucco is also an excellent non-combustible covering option. Both materials have the added advantages of being rot and rodent proof, low maintenance, requiring infrequent or no painting.

Roofs need to be constructed with non-flammable underlayment on top of plywood sheeting, which is better than oriented strand board, a composite material commonly used. Superior roofing materials are tile, metal, cementitious composites and slate. Stay away from wood shingles or shakes, even when treated with fire retardant. Don’t forget to clean gutters regularly to maintain fire safety.

Double pane windows perform far better than single pane in resisting sudden spikes in temperature during wildfires and impact from wind-driven flying firebrands. Such spikes often cause window blowout. Smaller panes survive better than bigger ones. Wood, wood clad with aluminum, metal and fiberglass frames all perform well—certainly better than vinyl frames. All exterior doors should have a one hour fire rating.

Selecting high performance foundation, eave and attic vents is critical for creating a fire-resistant dwelling shell. Soffit and attic vents can be eliminated by using icynene insulation (an open cell foam) on the underside of the roof, the only code-approved way to do so. In homes with crawl spaces, foundation venting is required by code for moisture control. Baffle vents, auto-closing vents and 1/8” screened vents are recent developments specifically designed to protect vent openings from heat and embers. In wildfires, there are hundreds of thousands of flying embers driven far ahead of the fire front by strong winds. Most are small and go out immediately. The larger ones can get pushed into any opening in the house shell, where they can smolder for hours, until possibly igniting nearby combustible materials and burning the house down.

Wildfires are important to the health and beauty of natural landscapes. Their periodic pattern reduces fuels, recycles nutrients, regenerates plants and stimulates biodiversity. We cannot “fireproof” forests, grasslands or shrub lands that depend on fire, but we can design, build and remodel homes to be more fire resistant.