Quick Answers
There are a few quick answers to how you can clear a firewall:
- Use a fire rake or hoe to clear debris away from the base of the wall
- Carefully use a chainsaw to cut down any trees or brush touching the wall
- Spray water on the wall to wet any vegetation and prevent ignition
- Remove leaves, pine needles and other flammable materials 5-10 feet away from the wall
Clearing the area around a firewall helps prevent flames from climbing up the wall and spreading to other areas. It’s an important part of creating defensible space around a structure and increasing its chance of surviving a wildfire.
Assessing the Fire Wall
The first step in clearing a firewall is to assess what type of vegetation and hazards currently exist. Consider the following:
- How close are trees and shrubs to the wall? Anything touching or overhanging should be pruned or removed.
- Is there a buildup of leaf litter, pine needles, grass or weeds along the base? These fine fuels can easily ignite.
- Are there ladder fuels like vines or shrubs that could allow fire to climb the wall? These should be cleared.
- Are the plants and vegetation moist or dried out? The fire risk increases with very dry vegetation.
Identify any vegetation that could act as fuel for an approaching wildfire. The goal is to remove anything that would allow flames to spread vertically up the firewall or horizontally across the ground to the wall.
Zone 1 Clearance (0-5 feet from the wall)
Zone 1 is the area immediately adjacent to the firewall, within 0-5 feet. This zone requires the most aggressive clearing to prevent direct flame contact to the structure.
All flammable vegetation must be removed down to bare mineral soil. Clearing should include:
- Cutting down trees and large shrubs near the wall
- Pruning back any overhanging branches
- Raking away leaf litter and debris
- Removing weeds, grass, vines and wildflowers
It may be necessary to apply herbicide or lay gravel/pavers to prevent vegetation regrowth near the wall. The goal is to remove any fuels that could transmit fire directly to the firewall.
Zone 2 Clearance (5-30 feet from the wall)
Zone 2 extends from 5 feet out to 30 feet away from the firewall. The focus here is on horizontal continuity of fuels. Eliminate shrubs and trees that would allow fire to spread rapidly across the ground to the structure.
Specific actions for Zone 2 include:
- Cutting down small trees and shrubs
- Pruning lower branches of large trees to a height of 15 feet
- Removing ladder fuels like vines and shrubs under trees
- Raking pine needles, leaves and debris
- Thinning dense stands of trees and shrubs to create spacing between canopies
The minimum distance between tree canopies should be 10 feet. For smaller shrubs, spacing should be 2-3 times their mature height. This helps reduce the intensity and spread rate of a fire blazing through the area.
Zone 3 Clearance (30-100 feet from the wall)
Zone 3 extends from 30 feet out to 100 feet away from the firewall. This area focuses on interrupting the vertical continuity of fuels by pruning and thinning vegetation. Specific actions include:
- Pruning tree limbs to a height of 10 feet.
- Thinning trees and shrubs to create appropriate spacing for the species.
- Removing ladder fuels under trees such as vines and shrubs.
- Removing heavy accumulations of woody debris.
The goal in this zone is to reduce the intensity of an approaching fire by interrupting fuel continuity both horizontally and vertically. This will help lower flame lengths and slow the spread of fire near the structure.
Methods and Tools for Clearing
Having assessed the vegetation near the firewall, the next step is to actually clear the identified fuels. Several methods and tools can be used:
Manual Tools
- Fire rakes – Use a stiff rake with short metal tines to scrape away leaves, pine needles and debris down to bare soil near the wall.
- Hoes – Use a hoe to break up packed debris and dig down through grassroots adjacent to firewall.
- Loppers – Hand pruners mounted on long handles for cutting branches up to 2 inches thick.
- Hand saws – Small saws for pruning branches and cutting down small shrubs or trees near the wall.
- Pulaski axe – Combination chopping and cutting axe effective for clearing saplings and brush.
Manual tools work well for smaller clearance jobs near the firewall. They provide precision in removing fuels while minimizing ground disturbance.
Power Tools
- Chainsaw – Gas-powered chainsaw effective for cutting down trees and heavy pruning. Requires safety gear.
- String trimmer – Powered rotating string to cut down grass and light vegetation near the firewall.
- Pole pruner – Manual or powered pruner on an extension pole for cutting high branches.
- Brushcutter – Heavy duty powered cutter for cutting down thick vegetation and saplings.
Power tools allow clearing thicker vegetation faster and farther from the firewall. Safety equipment like chaps, helmet and gloves are essential when operating chainsaws or other motorized equipment.
Herbicides
- Applying herbicide to the ground adjacent to the firewall prevents regrowth of weeds, grass and brush. This provides ongoing control of fine fuels.
- Target unwanted vegetation for removal first. Then apply herbicide to remaining stumps and roots.
- Use extreme caution to avoid herbicide runoff which can damage the surrounding environment.
Herbicides provide an option for controlling vegetation regrowth near the firewall over multiple seasons. However proper application practices must be followed to avoid environmental impacts.
Heavy Equipment
- Skid steers with masticating heads chop up and grind brush, trees and vegetation.
- Excavators and backhoes allow grubbing and removal of stumps near the firewall.
- Bulldozers scrape away heavy accumulations of debris and can stack or pile cleared fuels.
Heavy equipment requires expert operators but allows large scale vegetation removal. It’s most practical for larger properties or community fuelbreaks near the wildland interface.
Disposing of Cut Fuels
Once vegetation has been cut near the firewall, the cleared materials still pose a fire hazard until properly disposed of. Options include:
- Chipping – Use a woodchipper to break down debris into small pieces that decompose.
- Burning – Incinerate piles of dry debris using best practices for an air curtain burn.
- Hauling – Load debris in trucks for transfer to a landfill or recycling facility.
- Lop and scatter – Cut debris into small pieces and spread thinly over the ground to decompose.
Avoid leaving heavy piles of cleared vegetation near the firewall. They can become even more hazardous fuels as they dry out. Handle and dispose of cleared materials promptly and properly.
Maintenance of Defensible Space
Initial clearing is just the first step. Expect to perform annual maintenance to uphold defensible space near the firewall including:
- Raking leaf litter and debris that accumulates over time
- Mowing or using string trimmers to cut down annual grass and weed growth
- Pruning trees and shrubs to maintain proper height and spacing
- Removing young trees and brush that become established
- Applying additional herbicide to prevent regrowth near wall
Vigilant upkeep is required to account for factors like plant regrowth, windfall, leaf drop and pine needle accumulation over time. Aim to re-clear zones near the firewall at least annually.
Other Firewise Practices for Firewalls
In addition to vegetation clearing, some other measures can improve firewall effectiveness:
- Clean debris from the roof and gutters regularly to prevent ember ignition.
- Keep garden tools like rakes and hoes near the house for fire emergencies.
- Attach hoses to spigots with automatic timers for emergency sprinkler activation.
- Ensure driveways have adequate width and vertical clearance for fire trucks.
- Post clear street signs and home addresses for quick responder access.
Simple ongoing maintenance steps will prepare the home and firewall itself for potential wildfire threats. Firewalls provide critical protection but need proper care to live up to their full potential.
Improving Fire Resistant Construction
For new firewall construction, or remodeling existing walls, certain principles can enhance fire performance:
- Use non-combustible exterior siding like brick, concrete or stucco.
- Include sheathing layers like gypsum board under siding.
- Box-in eaves, but provide ventilation through fire resistant vents.
- Use dual pane windows with tempered glass.
- Seal cracks, joints and openings with fire resistant caulk.
Consult with qualified architects and builders to incorporate fire resistant designs and materials into new firewall projects. This enhances the protection provided by defensible space clearing around the structure.
Community Efforts for Fire Safety
For neighborhoods with multiple homes, consider organizing community vegetation management programs. This can include:
- Establishing community fuelbreaks by thinning vegetation along access roads and the neighborhood perimeter.
- Organizing communal work days for assisting elderly or disabled neighbors with clearing.
- Pooling resources to rent equipment and chippers as a group.
- Applying jointly for grant funding to support mitigation efforts.
- Developing contacts and information sharing with local fire districts.
By working together, communities gain efficiency, cost savings and shared responsibility for managing wildfire risks. Develop relationships and engage in ongoing cooperation to prepare for fires.
Conclusion
Proper maintenance of defensible space is crucial to maximize the effectiveness of firewalls. This includes:
- Assessing vegetation around the wall and identifying hazards
- Clearing fuels incrementally within defined zones
- Using manual tools, power equipment and herbicide judiciously
- Disposing of cleared debris safely
- Performing annual re-clearing and Firewise maintenance
With persistent care, a well-prepared firewall and defensible space improves the odds of a home surviving a passing wildfire. But the risk cannot be eliminated entirely in fire-prone regions. Creating fire-adapted communities and promoting overall forest health are key to coexisting with wildfire long-term. Defensible space helps shield individual homes, while proactive fuels management must occur at a landscape scale to restore ecosystem resilience. Ongoing community engagement provides the foundation to prepare for inevitable fire seasons ahead.