USA: Hot in the Shade: Inside Durham’s New Tree Preservation Rules for Developers

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Warwick Legal Network
14 března, 2024


On September 5, 2023, the City of Durham adopted a text change to its Unified Development Ordinance (“UDO”), which sets new rules for phased development and tree preservation for new developments. These changes, which were in part modeled on the Town of Cary’s grading ordinance, will significantly affect future projects in Durham.

It is not unusual for a multi-phase development to have all its grading done at once. Durham’s UDO defines “mass grading” as grading of four acres of more at one time to prepare for development of one or more lots. With grading and site development comes the clearing of trees. Since 1999, the UDO has had minimum requirements for tree coverage during development. Since 2019, it has required that some trees be preserved, rather than replaced, wherever possible. During this time, projects that mass grade, depending on the zoning, have been required to use additional buffers, however there has been no specific requirement related to phased development.

Now, in response to concerns related to erosion that may result from mass grading multiphase developments, the City has adopted new mass grading and phasing rules.

New Mass Grading and Development Phasing Rules

The text amendment creates several restrictions to discourage mass grading.

Developments that utilize mass grading will now be required to provide a 10’ no-grading setback from all development site boundaries. For projects that utilize grading but grade less than 4 acres at once, a 5’ no grading setback will be required. Additionally, all residential developments in Durham that utilize mass grading will be required to utilize natural vegetation to provide opacity levels of 60% or more along the project boundary buffers.

These changes are intended to address issues with erosion control and the visual impact of mass graded parcels prior to the commencement of vertical construction. However, these changes also limit the construction envelope of new projects and add complexity to site planning.

While these changes alone have the potential to increase development costs in Durham, the most significant change is the new phasing rules. Under the new rules, no individual development phase shall be allowed to exceed 50 acres. Further, each phase of a development will be required to meet the required minimum tree coverage percentages as well as provide the utilities, fire protection, right of-way infrastructure, and stormwater management necessary to serve that phase.

In effect, Durham is reducing the maximum effective size of developments by setting a phase size cap and forcing each phase to stand alone.

The new phasing rules may significantly impact the construction timelines for future projects. While a multi-phase project still will be able to be approved through a single site plan approval process, a water and sewer extension permit will need to be sought for each phase of the project. Moreover, no land disturbing activity on a future phase shall commence until after the first asphalt layer of the street of the previous phase has been laid and inspected and the lot(s) in the previous phase have been stabilized, inspected, and approved per the county and state sedimentation and erosion control standards.

New Tree Preservation Rules

The new text amendment also sets new rules for tree preservation in an attempt by the City to encourage tree preservation over tree replacement and increase overall tree canopy coverage percentages for new developments.

New projects that exceed 35 acres for a single phase will soon be required to provide 30% tree preservation, meaning that 30% of the site will need to be covered by preserved trees. Projects with phases that are less than 35 acres in size and projects with phases greater than 35 acres but include varied housing types, affordable housing, or additional environmental protection measures will be required to provide 20% tree preservation. Developments will still have the ability to utilize tree replacement if preservation is not possible, but the required tree replacement percentage will be larger than the applicable tree preservation percentage.

These measures will succeed in incentivizing the preservation of existing mature trees, but they also will have a cost. These new measures will require development site planners to get more creative to maximize the use of developable land and project yields may drop as more developable land will need to be covered by existing or replacement trees. While these changes may produce more verdant development, developers may need to utilize more diverse housing types in order to maintain project yields or resort to building fewer but larger and more expensive homes.


For further information, please contact:

Nil Ghosh, Partner

Morningstar Law Group, Durham


t:  +1 919 590 0362


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