How to Protect Your Trees When Your Neighbor is Developing Their Lot

How to protect your trees

Damage to your trees from development can happen in many forms, but root damage is the most overlooked, and often highest impact side-effect of development. Tree roots do not care about property lines, but can get impacted by a neighboring project.

Whether you’ve heard there is a development next door, or you got a notification required by our ordinances, it is good to know what impact a development project can have on your mature trees. Here are some basic guidelines on what you can do to work with the impact to your trees.

Get a Copy of the Plan

The best information you can have is to know where damage may occur, is to get a copy of the plan. Start by speaking to your neighbor, or the developer working on the project, to understand where the impact may occur. The earlier you coordinate with the project, the more likely it is that you can influence the impact to your trees, and reduce damage.

Understand Where Your Tree Roots Are

Critical root zone

Tree roots grow in the top 2 feet of soil in Northern Virginia, and go out quite far from the trunk. An easy way to understand where your roots might be is to measure the trunk in inches, take that number, and project it in feet, away from the trunk. The critical roots of a 12 inch tree, are likely to spread over 12 feet away, and a 40 inch tree over 40 feet away. Of course tree roots are rarely strong enough to go through buildings or other hard material, but drawing this “Critical Root Zone” can help you understand the impact. Sometimes, with larger projects, this may already be on the plan, prepared by a private arborist. To learn more about critical root zones, check out our explanation at the following link: 
Critical Root zones.

Work With the Project to Reduce the Disturbance to Your Roots, and Consider Hiring a Private Arborist

If the critical root zone of your tree is more than 30% severed by the project, either the project should look at reducing its impact, or the tree may not survive the impact. Changing the footprint of a proposed building or structure, or reducing grading around the tree’s roots can help reduce this impact. Other techniques, such as root protection matting, or root aeration matting, can also help with this.

If in doubt, work with a private International Society for Arboriculture (ISA) certified arborist specializing in Pre-construction tree protection (found here:, or a member of the American Society of Consulting Arborists (ASCA, found here: )

Communicate the Value of Healthy Mature Trees to Your Neighbor

Mature trees on and around your property can increase your property value greatly, and this may help your neighbor understand the need to adjust their plans to preserve your trees. We all benefit from a healthy, green canopy, and we can work together to help maintain it. Use the Tree Stewards’ handout on the value of mature trees. Find out other great ways to communicate their value at the Arbor Day website.

Mitigate Damage

Watering and mulching the critical root zone of the tree, after damage has occurred, can help improve the tree’s chance of survival. Be careful not to buy services without assessing their need. Services such as fertilization, fungal injections, and other soil improvements have not proven to have significant benefits.

Contact our Virginia Cooperative Extension Office to speak with someone about best solutions to ensure tree survival:

Other information on how to best protect trees can be found here: Avoiding Tree Damage