Install Tree Protection Fencing
Mature trees add $10,000-$50,000 to property values—but construction equipment can kill them in a single afternoon. Protect your trees' critical root zones with proper fencing before heavy equipment arrives on site.
Quick Summary
Time needed
2-4 hours
Cost
$100-$500
Professional help
Optional (arborist)
Why This Step Matters
Tree roots extend far beyond the visible canopy—typically 2-3 times the branch spread. These roots are concentrated in the top 12-18 inches of soil. A single pass of heavy equipment compacts this soil, crushing roots and cutting off oxygen. The tree may not show symptoms for 2-3 years, then suddenly die.
Hidden Damage
Root damage often doesn't show immediately. A tree can look perfectly healthy for 2-5 years after construction, then decline rapidly and die. By then, it's too late to fix. Prevention is the only solution.
Understanding the Critical Root Zone
The Critical Root Zone (CRZ), also called the drip zone or tree protection zone, is the minimum area around a tree that must be protected. Here's how to calculate it:
Calculating Protection Area
Measure trunk diameter at 4.5 feet above ground (DBH - Diameter at Breast Height)
Multiply by 1 to 1.5 feet per inch of trunk diameter
Example: 20-inch trunk = 20-30 foot radius protection zone
| Trunk Diameter | Min Protection Radius | Ideal Protection Radius |
|---|---|---|
| 6 inches | 6 feet | 9 feet |
| 12 inches | 12 feet | 18 feet |
| 24 inches | 24 feet | 36 feet |
| 36 inches | 36 feet | 54 feet |
How to Install Tree Protection
Identify Trees to Protect
Walk your property and identify all trees within 50 feet of the construction area. Pay special attention to:
- • Large, mature trees (highest value)
- • Heritage or protected species
- • Trees on property lines (may be shared with neighbors)
- • Trees providing shade to your house
Mark the Protection Zone
Using the CRZ calculations above, mark the protection boundary around each tree. Use spray paint, flags, or stakes to create a visible perimeter.
Pro tip: When in doubt, go bigger. It's much easier to reduce the protection zone later than to save a dying tree.
Install Fence Posts
Drive metal T-posts or wooden stakes at 8-10 foot intervals around the protection zone boundary. Posts should be at least 4 feet tall and driven 18-24 inches into the ground.
- • T-posts: More durable, can be reused
- • Wooden stakes: Cheaper, easier to install
- • Rebar: Budget option, add visibility flags
Attach Fencing Material
Wrap the posts with highly visible fencing. Orange construction fence is the standard choice—it's cheap, visible, and clearly communicates "do not enter."
Fencing options:
- • Orange plastic mesh fence ($20-$50 per 100 ft)
- • Chain link fence (more secure, $100+ per 100 ft)
- • Silt fence with visibility tape (budget option)
Add Signage
Post clear signs on the fence at eye level. Signs should state:
TREE PROTECTION ZONE
NO ENTRY - NO STORAGE - NO DIGGING
Do Not Move or Remove Fence
Add Root Zone Mulch (Optional)
For extra protection, spread 4-6 inches of wood chip mulch inside the protection zone. This helps if foot traffic or light equipment must occasionally enter the area.
Mulch matters: Keep mulch 6 inches away from the trunk to prevent rot. Spread it evenly to the fence line for maximum protection.
City Tree Protection Requirements
Many cities have tree protection ordinances that apply during construction. Violations can result in significant fines and required replacement plantings.
Common Requirements
- • Protection for trees over certain diameter
- • Minimum protection zone sizes
- • Fence specifications (height, material)
- • Arborist inspection before/during/after
- • Tree protection plan submittal
Potential Penalties
- • Fines: $500-$10,000+ per tree
- • Required replacement plantings
- • Stop-work orders
- • Permit revocation
- • Tree valuation damages
Check your permit: Tree protection requirements are often included as permit conditions. Review your building permit for specific tree protection requirements.
If a Tree Must Be Removed
Sometimes trees directly conflict with the addition footprint and must be removed. Most cities require permits for removing trees above a certain size.
Never Remove First, Ask Later
Removing a protected tree without a permit can result in fines of $10,000 or more per tree, plus required replacement plantings. Always check permit requirements before any tree work.
Tree Removal Permit Process
- Apply to your city's planning or urban forestry department
- Provide tree species, size, location, and reason for removal
- May require arborist assessment for large or heritage trees
- Expect to plant replacement trees (often 2:1 or 3:1 ratio)
- Permit fees: $25-$500 depending on tree size and jurisdiction
Frequently Asked Questions
Can I just protect one side of the tree facing construction?
No. Tree roots extend in all directions, and compaction on any side can damage the entire root system. The protection zone should completely encircle the tree, even if construction only happens on one side.
What if my contractor needs to temporarily enter the protection zone?
Brief foot traffic is usually okay if the ground is covered with plywood sheets or thick mulch. However, no vehicles, heavy equipment, or material storage should ever enter the zone. If access is truly necessary, consult an arborist first.
How close can I build to an existing tree?
This depends on the tree species, size, and your willingness to accept some risk. Building within the CRZ will damage roots. Some trees tolerate 20-30% root loss; others will decline. An arborist can assess your specific situation and recommend mitigation measures like root pruning or aeration.
My neighbor's tree overhangs my construction area. What are my rights?
Generally, you can trim branches that overhang your property, but you cannot damage the tree itself. Before cutting any branches over 4 inches diameter, check local regulations and consider notifying your neighbor. Damaging a neighbor's tree can result in liability for the tree's full value.
Ready for the Next Step?
With trees protected, the next step is setting up construction fencing and barriers to secure the site, protect your landscaping, and ensure pedestrian safety.