This spring while you’re working in the yard to spruce up the place, be sure and make a defensible space!
Defensible space is a phrase used a lot when talking about wildland fires and wildland-urban interface areas (where wildlands meet homes and farms). So what is a defensible space? Depending on your location, it is the area around your home up to 200 feet that has had fire fuels removed or reduced through things like landscaping.
While we do have our share of wildland-urban interface areas in our response district, even people living within city limits can use some of the tips! Keeping a defensible space around your home within the city limits can help reduce the spread of fire from your house to your neighbor’s house or an outbuilding (and vice versa), give firefighters room to maneuver and fight fires on your or your neighbor’s property, and can even reduce your risk of burglary.
The defensible space is divided into three sections that are simply called Zones 1-3. Each of the zones goes out a certain number of feet from your house or the previous zone’s border in a circle. How many zones and how large each zone is depends on the location of your home in relation to other homes and wildland and the topography of your property. For properties that are close together, it is important for everyone to work together on creating a defensible space for everyone.
These three zones encompass what is called the Home Ignition Zone. Studies have shown that the 200 or so feet around a home are very important during wildfires. The three main sources of ignition – embers, surface fires, and crown fires – can each ignite a house in its own way once it breaches the Home Ignition Zone. Embers are very sneaky. They are carried on the wind from nearby fires and get into open vents and windows, the tiny recesses of the roof, the corners of houses, and underneath decks and other outdoor attachments. Once in, they can create small or large fires in and around your home. Surface fires often ignite houses in a more direct manner. They tend to be smaller flames that feed off grass, leaves, twigs, and needles located on the surface of the ground as well as short shrubs and low hanging tree branches. They tend to move very quickly. Unless stopped, they continue following the surface materials along until they run into – and ignite – something bigger, like a house. Crown fires take place in the canopies or tops of trees. They are extremely intense and move very quickly through densely connected canopies – like those of a forest. The wind plays a large part in spreading these fires. The heat they generate can even ignite wood walls up to 30 feet away!
Zone 1 is often considered the most important zone and it is recommended that if you are just creating a defensible space that you start here! It also happens to be the one that anyone with a yard can implement in some way as it is the zone closest to the house! Zone 1 includes the house and extends out 30 feet in all directions from the end of the house and its attachments – in order to protect your home from heat radiating from large fires!
Tips for Zone 1 include:
- -Perform house maintenance to prevent embers from getting inside. Repair or replace broken or missing siding and roof shingles or tiles. Caulk in remaining gaps. Cover any exterior attic vents. Softfit and under-eave vents should be enclosed in 1/8 inch or smaller metal wire mesh. It’s recommended that people start working on their house and then work their way our from the house, foot by foot and zone by zone. But if you can’t start here, start where you can!
- -Keep grass mowed. Grass clippings should be disposed of as soon as possible.
- -Keep all grass, trees, plants, and even mulch well-watered.
- -Remove vegetation from under decks and other attachments. Replace with non-flammable options such as rocks or gravel.
- -Any dead vegetation should be cleared out to at least 10 feet from the house and attachments but a full 30 feet is preferred.
- -Clear out places where leaves, needles, twigs, etc. tend to gather, such as in the gutters,corners of homes, eaves and under decks. Dispose of debris as soon as possible. These are excellent fuel sources for embers.
- -Wood piles and propane tanks should not be stored against the house, attachments, or other structures. Ideally, they should be outside of Zone 1 completely.
- -The first 5 feet from the home and attachments should only include non-flammable materials or high-moisture annuals and perennials.
- -Any vegetation you choose to use against the house should be short. Tall shrubs are not only fire hazards, particularly at windows where their fires can break windows and/or lead flames directly into your home, but they also can help criminals! People often think that if they plant large shrubs in front of their windows, it will give their family privacy and deter burglaries. What shrubs actually do is give burglars privacy to break into your home without your neighbors seeing them!
- -All plants in this zone should be short, well-spaced, and well maintained. Do not use plants that have wax, resins, or oils.
- -All trees should be cut back so they do not hang over the house. They should also be pruned regularly so that their branches are 6-10 feet off of the ground. Conifer trees should be spaced so that there is at least 30 feet between their crowns to stop crown fires from spreading through radiant heat and direct contact.
- -Play equipment, decorations, patio furniture, fences, etc. in this zone should be non-flammable or fire resistant. Right down to the pillows on your deck chairs!
Zone 2 starts 30 feet from your home and extends to 100 feet from your home.
Tips for Zone 2 include:
- -All vegetation in this zone should be well watered.
-Plants should continue to be short and well maintained. Use fire resistant plants in this zone as well.
-If you choose to use shrubs in this zone, they should be short and they should not be a continuous line – while you may think that they look nice or provide you with privacy, they actually provide a straight line of fire fuel! Space them out!
-Both deciduous and coniferous trees can be in this zone. All trees should be pruned so that all branches are at least 6-10 feet off the ground. Individual trees should be spaced 20 feet apart. Trees can also be in small clusters of 2-3 trees that are spaced 30 feet from other tree clusters or individual trees.
-Use driveways and walkways to break up the various vegetation. This breaks up a fire’s line of fuel as well! If you live on a larger property with a very long drive, you also need to make sure that there is a 10-12 feet clearance on both sides of your driveway and 14 feet clearance overhead. Clear out overhanging branches and dead vegetation. Your driveway should also be wide enough and stable enough for fire equipment to use, including all bridges and gates. Ideally, all large properties should have two points of access. With two points of access, if your property is threatened by fire or has an active fire, responding units have a second way to get on your property if one is blocked by fire or they can use both points of access at once if the situation calls for it.
Zone 3 starts 100 feet from your home and extends to 200 feet from your home or beyond. If you have a 20-39% slope, it is recommended that you extend this zone 200 feet downhill. If you have over 40% slope, you should extend 400 feet downhill.
Tips for Zone 3 include:
-Clear out snags – dead or dying trees that are still standing. There should be no more than 2-3 snags per acre. Any snags that remain should not pose a threat to power lines, access points, or roads.
-Remove large woody debris, such as logs, branches, and sticks, so they do not accumulate.
-Remove smaller coniferous trees that grow between larger trees.
-Thin tall trees by removing live branches to ensure that tree canopies do not touch and to reduce tree density.
As you can see, the keys to a defensible space around your home is thoughtful landscape planning and maintenance.
Wondering what plants are not only appropriate for a defensible space but also appropriate for our climate? Check out this awesome guide on fire resistant plants perfect for growing in the Willamette Valley put together by Oregon State University‘s Extension Service! Know someone out of state you’d like to share this information with? Send them this site for appropriate plants for different US states and regions!
If you’re planning a construction or renovation project, this guide from the National Fire Protection Association shows you what materials can help make your home, attachment, or other structure more fire resistant!
If you’d like the TL;DR version, check out this quick checklist for some of the top tips to create a more defensible space around your home!