Tree protection plans: what’s required and why

What is a tree protection plan?

A tree protection plan (TPP) sets out how trees will be protected through demolition and construction. It’s separate from the arborist report, though the two are usually prepared together and sometimes submitted as one document.

The report assesses the trees and makes recommendations. The plan turns those recommendations into instructions for construction. It tells the contractor, the grading engineer, the site superintendent and the municipal inspector exactly where protection goes, what form it takes and what’s restricted near each tree.

A tree protection plan isn’t a wish list. Done properly, it’s an enforceable part of the site approval.

When does your project need one?

For most projects involving protected trees, it’s part of the application. Municipalities ask for it with the development application or building permit, and some won’t clear the building permit until the plan is accepted and the hoarding has been inspected.

• Site plan applications. Urban forestry staff comment on site plan applications, and their conditions usually require a tree protection plan in place before construction.
• Building permits near protected trees. In Toronto, work affecting a protected tree needs a tree permit with a protection plan. Other municipalities have similar rules.
• Committee of Adjustment and consents. Conditions on minor variances and consents often include tree protection, especially where neighbours or staff have raised concerns about adjacent trees.
• Infill and intensification. Laneway suites, garden suites, rear additions and severances almost always need one, because the footprint and access routes conflict with existing trees.
• Demolition permits. In Toronto and elsewhere, a plan may be needed before an existing building comes down, because demolition damages roots too.

What a tree protection plan includes

Requirements vary by municipality, but a complete plan typically covers:

• Tree inventory and location. Every tree on the property and within the zone of influence next door, with species, DBH, condition and status (preserve, injure or remove), plotted on the site plan at a legible metric scale.
• Tree protection zones. A calculated TPZ for each retained tree, based on trunk diameter and enlarged where the site or the tree’s condition warrants. Inside it, construction activity, storage, grade changes and equipment are restricted.
• Protection measures. The type, location and specification of every barrier, usually solid or framed hoarding at the TPZ edge, and the conditions under which it can be moved temporarily.
• Construction methods inside the TPZ. Hand digging within a set distance of the trunk, bridging over roots, root pruning ahead of excavation, or arborist supervision of certain work.
• Grade changes. What cut or fill is allowed inside a TPZ, how deep, and how roots will be protected.
• Underground services. How water, sewer, gas, hydro and telecom will be routed around roots, with directional boring or hand digging where they can’t be.
• Pre-construction pruning. Clearance pruning needed for equipment, completed by an arborist before work starts.
• Inspection and monitoring. Who verifies the protection is in place, how often the site is monitored, and what needs supervision.
• Post-construction care. Decompaction, watering or monitoring for trees that took construction impacts.

What makes a plan work on site

This is the part most clients don’t think about until something goes wrong. A plan that passes municipal review and a plan that protects trees during construction aren’t automatically the same thing.

Specificity

Vague plans fail on site. “Trees will be protected” gives the superintendent nothing to follow and the inspector nothing to enforce. A plan that gives the exact hoarding location, the distance within which hand digging applies and the condition of each tree can be followed and checked.

Constructability

A plan drawn without understanding the build sequence, equipment and staging gets set aside when construction starts. It has to work within the realities of the build, not just on paper.

Field implementation

Someone has to install the protection, check it and be on call when questions come up. I design and install tree protection hoarding for my projects, so the person who wrote the plan is the person who put it in the ground.

Contractor education

The best plan fails if the excavator operator doesn’t know it exists. Before work starts, someone needs to walk the contractor through what’s restricted, why, and what happens if it’s ignored. That short conversation is worth more than any amount of fencing.

Tree protection zones: how they’re calculated

The tree protection zone is the area around a tree that has to be kept free of construction impacts to give it a reasonable chance of survival. It’s based on trunk diameter, so larger trees get larger zones.

Most municipalities publish a minimum zone that grows with the trunk diameter, and staff can ask for more where the site calls for it. Hamilton works from the drip line instead.

Inside the TPZ, these are typically restricted or prohibited without specific approval:

• Soil compaction from equipment, storage or foot traffic
• Grade changes, whether fill or excavation
• Underground services without an approved method
• Parking or storing equipment, materials or waste
• Burning or chemical use
• Root cutting beyond what the plan specifies

Absorbing roots often reach well past the TPZ boundary. The zone is a minimum, not a guarantee. The goal is to protect the structural and transport roots well enough that the tree has a reasonable chance of long-term survival.

Why the plan doesn’t end at approval

Approval is the start of tree protection, not the end. During construction, equipment ends up where nobody planned, services hit roots that weren’t found beforehand, and subcontractors work near trees without reading the plan.

Monitoring visits check that protection is in place and intact, put an arborist on call for judgment calls, document compliance for the municipality, and catch problems early, before a small root intrusion becomes a dead tree. A simple addition near one neighbouring tree might need only a pre-construction inspection and a verification letter. A multi-unit infill site with several large retained trees needs regular visits through the build. See construction monitoring.