Tree Protection Guide for Toronto Construction Projects

Toronto’s urban development projects usually integrate some elements of ecological conservation, particularly when it comes to cutting and isolating mature trees sited on and off development parcels. As part of planning policy and urban risk management, tree protection is fundamental to risk and liability management. This document intends to explain the steps necessary for effective tree protection in the GTA by explaining the legal obligations, the level of compliance, and the functional aspects of tree preservation during construction works.

A TPZ in Toronto is illustrated as a fenced-off area around a tree designed to protect its roots, trunk, and canopy while shielding construction processes. TPZs avoid soil compaction and root severance, as well as prevent mechanical injury, which are the three main causes of tree decline during building work.

In the course of work related to building and construction, over seventy percent of the root systems of urban trees are located in the top 30-centimeter soil profile, as stated by the Canadian Urban Forest Strategy, making them susceptible to rooting, grading, or material positioning. Root damage of more than 40 percent is known to significantly reduce a tree’s survival rate within five years post-construction, as proven by research carried out by the International Society of Arboriculture.

Practically, a TPZ's minimum distance is calculated as a function of the circumference of the tree at waist height DBH, with a common formula being 30 cm of protection for every 2.5 cm of DBH. In addition, Toronto's municipal guidelines stipulate that protective fencing be made of robust material with full radius extension and clear markers defining boundaries. Such markings must be done before the building permit sign-off.

In the GTA, known practitioners of real estate and public infrastructure works are using TPZ recommendations mostly not for the sake of compliance, but to mitigate tree damage liability in the long term. A good example is the North York mid-rise development of 2022, which incorporated TAZs for 13 mature silver maples. All the trees were preserved, and this resulted in positive further assessment and public comment.

The main reason for the establishment of the TPZ structure was to protect trees from potential abuse caused by excessive construction site traffic, heavy equipment, and accumulation of construction materials. Protecting trees' roots damages during construction enhances urban greening, improves air quality, reduces stormwater runoff, and enhances the beauty of the city.

By the bylaw, a permit must be obtained before the destruction or infliction of any injury to privately owned trees that are 30 cm wide. In this sense, injury is sustained in any attempt that results in mechanical destruction to the tree’s structure; this includes, but is not limited to, excavation, chemical residue, and impacts.

Another vital aspect of the framework policies is that a certified arborist is responsible for the preparation of all the required documentation, which has to include a Tree Protection Plan. All protected trees have to be located on the site mandated by the boundary description of the proposed TPZs, which contain tree stumps, as well as parts of the trees in non-removal areas, as well as methods of construction mitigation and evaluation for any mitigation that might be necessary. Applications not including appropriate Tree Protection Plans are subject to disapproval from the city.

Permits for Tree Protection Plans are issued subject to their adherence to the compliance agreements outlined within the framework policy, which were made to be submitted alongside permit request papers. Site inspections are performed as obligatory pre-commencement measures before the commencement of construction activities post-verification approval.

For example, during a municipal road widening project in Etobicoke in 2021, contractors were required to implement tree preservation measures for 18 public trees along the corridor. Incorrect compliance with the protection plan resulted in administrative fines and enforced root aeration treatments after some compaction of soil was observed.  

This framework aims to protect the trees that provide critical environmental benefits from being destroyed due to urbanization. When these rules are followed, they aid in the preservation of Toronto’s urban forest and increase the city’s sustainability targets.

Scientific monitoring data from the Urban Tree Alliance (2021) indicate that trees protected according to municipal standards in dense urban environments maintained 94% canopy retention five years post-development. In contrast, trees exposed to root zone disturbance without protection dropped below 60%.

Toronto’s Don Valley redevelopment project provides a strong example. Preservation of over 50 trees adjacent to a high-density residential construction site was achieved using above-standard TPZ radii and scheduled arborist site inspections every two weeks. Notably, none of the trees required replacement or mitigation within two years post-construction.

In another case, a downtown condominium built integrated an early-stage tree assessment, which resulted in a minor site redesign. This change allowed for the preservation of a 70-year-old honey locust, which was originally marked for removal. The retention was credited to the project's LEED certification and supported the city’s canopy growth targets.

These examples underscore the importance of early planning and effective site management when working with protected trees. Projects that integrate tree protection into the design phase are more likely to experience success in both tree preservation and meeting municipal requirements.

From a business perspective, tree protection reduces risk, enhances long-term savings, and increases property value. Construction-related tree damage can incur municipal fines, remediation costs, and project delays, which eat into profit margins.

Moreover, Journal of Environmental Management studies suggest that mature trees can increase property value, especially in urban residential areas, by as much as 20%. Trees also provide a competitive sustainability edge in resale and leasing scenarios, helping enhance green-economy credentials for prospective tenants or purchasers.

As an example, in Toronto, the development projects that meet or exceed the city’s environmental criteria for tree retention enjoy faster approval cycles through incentive programs like the Green Standard Tier System. Preserving trees also aids in meeting stormwater runoff reduction, shade coverage, and regional biodiversity targets.

Project developers have begun factoring these benefits into their design as exemplified by a commercial redevelopment in Toronto which implemented root protection sensitive excavation and TPZ fencing to retain four red oak trees at the lot's perimeter, thereafter achieving reduced landscape restoration costs, elimination of replanting obligations, and significant public relations value upon project completion.

Property developers who prioritize tree preservation measures have a greater chance of improving their ROI by fostering an environmentally attractive urban area. By following the requirements for tree protection and incorporating them into the framework of the development project, these companies position themselves for long-term achievement in a green city.

It offers vast opportunities to sustain the health and vitality of the trees on the site when tree protection is integrated during the early proposed phases of the project, and not just site polices and regulations. Ensuring the trees are protected this early increases the chances of sustaining them during the extensive construction and development process.  

This is where architects, together with planners and certified arborists, need to be in sync and collaborate. The design team can offset construction impacts finely with tree cover by developing a detailed tree pruning strategy in conjunction with counter-mitigation measures regarding construction impacts on trees. Building placement, as well as the traffic routes, services, and other structures, can be relocated to avoid violations of the tree critical zones buffer.  

Tree protection measures greatly depend on the planning undertaken before the felling starts. Projects that practiced involving arborists during planning greatly benefited with tree coverage for the site, as they showed significantly lowered mortality rates of trees, up to 25% higher survivorship, than when tree protection measures were only considered post-settlement.

An extensive arborist report is generated, which includes the tree protection measures recommended to appropriately shield the trees situated on the project’s boundaries. The report includes graphed trees of certain species that are stricken with poor form and will be detrimental and thus need to be removed, while others may be preserved. Additionally, the arborist specifies how several tree protection zones will be put into place to allow construction activities to be regulated outside the root zones of the trees, limiting construction to prevent tree harm. In the city of Toronto, the tree protection rules demand an on-site assessment and the creation of a Tree Protection Plan, which is the foundation for securing the requisite permits.  

The project management functions of ArboStar provided solutions to the curbstone problems and, at the same time, enabled the tracking of heritage trees during the preconstruction activities. This ensured compliance with the applicable tree protection standards and that project management scheduling and planning were adapted, as needed, to maintain compliance with the project’s key constraints. All these efforts resulted in no costs being incurred in the case of the project and payments in the case of the regulatory frameworks.

ArboStar facilitates simultaneous supervision of the TPZs within the construction phase. The software assists construction teams and arborists to work together to make certain that trees are protected from harm during sensitive operations like excavation and material staging. In-tree protective measures zone mitigation due to the best planning and preconstruction efforts still pose a risk from various on-site activities, heavy tree bombardment, and machinery.  

ArboStar has a cloud system that permits construction users to monitor TPZs in real time. The portal will notify site supervisors automatically when encroachment activity is noted, giving them the necessary time to take action. Site supervisors regularly check TPZ barriers as a supervisory measure to confirm they are in place and effectively functioning. These measures include assuring compaction of the surrounding soil, presence of the TPZ barrier fencing, and absence of equipment or materials enclosed within the TPZ.

ArboStar’s system has developed because of advanced IoT technologies, enabling real-time monitoring of soil moisture and compaction for arboricultural practices. This allows arborists as well as construction teams to manage soil compaction proactively and avert problems to tree health. Identifying the compaction problem, in particular, is of great importance. A Journal of Arboriculture study highlighted that the oxygen and water retention capability of soil, vital for root health, is heavily impacted by compaction, even the weight of a backhoe. The soil suffocation, which leads to oxygen being unusable by tree roots, combined with a modest fifteen percent dip in soil porosity, would significantly diminish tree health in under a year.  

ArboStar tracks real-time soil parameters and weather conditions using GPS tracking augments in data-centrism with construction to help tree exhibitors analyze zones of conflicts in arboristry before regions are started, bordering excavation. This neutralizes ID conflicts at their genesis, spurring eco-awareness, aiming at sensitive tree relocation without construction disturbances.  

Efficient construction and arborist collaboration make certain that any encroachments during construction works are avoided near critical trees while the TPZs are respected and undermined by the confined area and bloodless during the active zone. The absence of these encroachments inevitably sealed the tree's long-term suffering due to the completed construction of enduring sensitivity, enabling decline and dead restrictions.

While appearing to focus on aesthetics, the landscaping phase is critical to the health maintenance of the protected trees. The grading and hardscaping done during this phase, as well as the use of machinery, can reverse the protection efforts made during the earlier phases. Therefore, root zones and the spatial environmental features of the tree need to be attended to.

In these steps, an arborist inspects the soil and the root area, and he also applies soil restoration techniques. These techniques include vertical mulching and air spading, both of which aid in relieving the compacted soil that may be present post-construction. These techniques will reintroduce oxygen to the roots, which leads to strong growth in the tree.

In addition, the arborist makes sure the replacement tree fits the conditions if they want to remove the tree because of construction injuries or diseases. The tree replacement is checked under the Urban Forestry Services of Toronto, which ensures it is ecologically suitable for the location, as well as meeting the set size and species guidelines.

Sometimes, the landscaping stage includes the lifting of temporary TPZ barriers. This phase, however, requires special attention to avoid further disturbance to a tree's root zone. All tree-adjacent grading or material placement must be executed in a damage-free manner.

ArboStar streamlines the post-construction monitoring process, offering businesses tools to evaluate tree health as well as report on any issues relevant to post-construction. This ensures that all possible steps are taken to construct recovery-induced damage and aid the healing process of the trees.  

ArboStar reports automatically to businesses, which allows tree care companies to capture and retain post-construction documentation. These reports include all forms of stress such as: a leaves discolouration aetiology, crown die back or root truncation, and recommend subsequent mitigation actions.  

The post-construction stage also comprises the additional action of monitoring to ascertain stress recovery as tree growth progresses. However, an actor during this stage is the emergence of damage not apparent at construction, but the adjustment of a tree to its surroundings results in growth changes, which set off the visio-motor growth response.

Scientific studies suggest that it could take as long as 18 months to see the full impact of construction damage on trees. This highlights why ongoing post-construction monitoring is critical. The ongoing vitality and health of trees after construction are heavily reliant upon prompt issue mitigation and known management after problem identification.

Tree preservation is significant to the urban construction undertakings in Toronto. As development progresses rapidly in the Greater Toronto Area, maintaining mature trees not only fulfills the legal requirements but also safeguards the city’s greenery for the upcoming generations. When tree protection is integrated with the design process as well as monitored closely during the execution phase, developers stand to gain the best results environmentally as well as for their projects.  

At ArboStar, we focus on offering tree care solutions specifically engineered for arborist companies. Our all-in-one platform simplifies compliance with tree care operations that require real-time monitoring and advanced management of tree protection services.  

ArboStar is the first choice when looking for tree care solutions, with tree care software that is tailored to arborist companies. Schedule your free demo today and learn why we are the best in the industry.