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Last week, I shared a story and video about the machine that "roll formed" our metal roof on site. This week, we'll consider the upcoming fire season and how your home can be designed to minimize the risk.

Designing Your Home to Survive Wildfires

The information below is an example of important information to relate to your builder and architect. They should be designing and building with fire safety in mind and building codes require some safety measures. However, it may be productive to express your needs and work with them on an overall plan.

This post is a chapter from our online course: Home Construction Navigator.

Wildfires are becoming a more frequent threat in many states and it's important for homeowners to learn about the risks and how to prepare homes to better resist destruction from fires. Whether or not a property is in a wildfire zone, fire safety should always be a consideration. Homeowners should assess their risk and make building decisions that fit not just building codes, but also their risk tolerance.

Materials

Let's start with the house itself. Choosing fire-resistant materials is the first step. Imagine a wildfire in the distance. The wind is whipping-up small pieces of burning embers that are floating to your property and landing on your roof. Your roof material can make a big difference in how your house fares in this situation. Having roofing material that is fire-resistant like metal or tile can be your first defense.

Consider other exterior materials on and around the structure and to what degree they are fire-resistant:

Siding
Trim
Fascia
Gutters
Decking
Railings
Posts
Vents
Chimney

Design

Those embers can also find their way into vents or under the house structure. Your construction team can help design the structure to prevent embers from entering. This can include using fine wire mesh or enclosing spaces around the house and deck. Eaves can be enclosed with ignition-resistant soffit material with screened vents.

Double or triple-glazed windows and doors and the use of tempered glass are also good choices to resist the heat of a fire. Installing fine metal screens on operable windows helps prevent embers from penetrating. In high-risk zones, some homeowners have hurricane-like fire-resistant shutters to cover windows during a threat.

For open structures, steel posts can be a good option. Wood posts can be treated or wrapped with fire-resistant material.

Systems

Exterior sprinkler systems can spray, saturate, and cool the roof, soffits, and siding so the fire has a much lower chance of igniting the material. These systems can be operated automatically with heat sensors or turned on with a manual valve.

Most standard builds have hose bibs on the front and/or back of the house. Extra hose bibs around a custom home, possibly one or two on each side of the house, depending on the house size, can be relatively inexpensive to install during a new build, and valuable during a wildfire or house fire threat.

If there is a wildfire threat and municipal water stops flowing, it can be a lifesaver to have water storage on the property. Tanks can be installed above ground or buried. These tanks can connect to the main water system of the house, or to the exterior fire sprinkler system and specific hose bibs as a safety net.

Perimeters

If structures are far apart, it's difficult for fire to reach from one to the other. When planning multiple structures, like a garage, workshop, firewood stack, garden shed, etc., plan for good separation from the house, if possible. This is especially true if a structure will hold flammable materials like many workshops and garages do.

This also includes wood fences that connect structures. The minimum distance published by many fire prevention agencies is 30 feet. Obviously, not every homeowner can meet these space requirements, but keeping this concept in mind as plans are being developed can lead to thoughtful fire-awareness decisions.

Flammable Liquids

Many homes store flammable liquids inside or near the home. These liquids can become a combustion risk if exposed to fire. To mitigate this risk, consider using a flammable liquids cabinet. These cabinets are designed to withstand high temperatures and help prevent explosions. Examples of liquids that can be stored include:

Gasoline
Methylated Spirits
Acetone
Paint Thinners
Aerosols

Home Ignition Zone

The home ignition zone was developed in the late 1990s and is based on the science of how homes tend to catch fire. The zone concept establishes perimeters around the home and what can be done within each perimeter to reduce fire danger.

Diagram and Zone information adapted from the National Fire Protection Association

Immediate Zone (0-5 Feet)

This is the most important zone and aims to be a non-combustible materials zone.

Roofs and gutters can collect leaves and debris that could ignite from embers. Consider the maintenance your roof design will require, and if there are any systems that could help, such as a gutter system that resists this debris collection, or eliminating a deep roof valley that will collect debris.
Install 1/8 inch metal mesh screening on vents to prevent embers from entering.
Install window screens on operable windows.
Screen or box-in areas below patios and decks with wire mesh or solid material to prevent debris from entering.
Keep any flammable material away from wall exteriors – mulch, flammable plants, leaves and needles, firewood piles – anything that can burn.
Consider a non-flammable ground cover perimeter against the house such as gravel.

Intermediate Zone (5-30 Feet)

In this zone, it's important to use careful landscaping to create breaks that help prevent fire from moving from the surrounding property to the home.

Clear vegetation from around large propane tanks.
Use driveways, walkways/paths, patios, and fire-resistant decks to create fire breaks.
Remove vegetation under trees so a surface fire cannot reach the crowns.
Prune trees up to six to ten feet from the ground.
Space trees to have a minimum of eighteen feet between crowns.
Place trees to ensure the mature canopy is no closer than ten feet to the edge of the home.
Limit trees and shrubs to small clusters of a few each.

Extended Zone (30-100 Feet)

Here the goal is to limit the fire's path to the home and keep smaller flames on the ground.

Dispose of heavy accumulations of ground debris.
Remove dead plant and tree material.
Remove small conifers growing between mature trees.
Remove vegetation adjacent to storage sheds or other outbuildings.
Trees 30 to 60 feet from the home should have at least 12 feet between canopy tops.
Trees 60 to 100 feet from the home should have at least 6 feet between the canopy tops.

Plan now for making fire safety a regular part of your home's design and maintenance routine.

Working with Construction Pros

An eBook for Homeowners

As a homeowner, your project depends on a team of professionals, like general contractors, architects, and more.

This is your guide to hiring, evaluating, paying, and working with them during one of your life's biggest projects.

That's what I have for now. See you next week!

Lee LeFever, Build Livable

Build Livable helps homeowners navigate custom home construction. Learn More.
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Designing Your Home to Survive Wildfires 🔥