Planning around trees

On this page

How to consider trees in your project

Trees need to be one of the first things considered in planning a project on your property.

If you are building an addition, installing a new deck or fence, putting in a pool, building a coach house, fixing any of your servicing, or any other construction project on your property, you may require a tree permit in addition to any other permit you need to do the work.

Familiarize yourself with the City’s Tree Protection By-law so that you know when a tree permit is required and how to protect trees that are located close to the work you are planning to do.

Use the Decision Tree tool to determine how to apply for a tree permit, if one is required.

Remember that obtaining any other type of permit from the City does not give you permission to remove trees that are protected under the Tree Protection By-law. This includes, but is not limited to Building Permits, Pool Enclosure Permits, Road Cut Permits, Demolition Permits, etc.

If you do not have to remove a tree to do the work that you are doing, that’s great! You still need to ensure that you are protecting the trees around your project adequately. Please refer to the City’s Tree Protection information to ensure that you are protecting trees while you are doing any construction work, no matter the scale. Injuring a tree that is protected under the Tree Protection By-law is a contravention of the by-law.

Here are some things to consider when planning your project to retain trees:

  • Remember that trees on neighbouring properties may have roots that extend into your property.
  • Determine the critical root zone (CRZ) of the trees on and adjacent to your property. The critical root zone is established as being 10 centimetres from the trunk of a tree for every centimetre of trunk diameter. The trunk diameter is measured at a height of 1.3 metres for trees of 15 centimetres diameter and greater and at a height of 0.3 metres for trees of less than 15 centimetres diameter.
  • Prioritize the protection of the trees when planning the project. Try to design your project around the trees so that no trees need to be removed, and no digging or excavation has to be done within the CRZ of any protected trees.
  • Work with an arborist to determine any required mitigation measures to put in place for any work near trees.

General rules for considering tree permits

This diagram illustrates how Forestry staff will generally approach the decision of whether or not to issue a tree permit. This is a very simple residential lot situation that can be applied easily to infill development situations, but the principles can be applied to larger or more complex development situations across the city.

The diagram shows, in general, when staff will likely issue a tree permit (YES) and when staff will be looking for tree retention (NO). It also shows the situations where it will need to be a site by site decision (TBD).

There are some important disclaimers for this diagram: this is a general set of rules that may not apply in all cases or on every site. The decision process will always depend on the condition of the trees, as well as the species, size, and location of the trees, along with the site conditions and the proposed development. However, this diagram represents what should be considered early in the site planning process and helps to show what City staff are looking for in terms of tree retention and protection.

diagram for trees around construction

Under the new Tree Protection By-law, Forestry staff will be looking for City-owned trees, for example street trees within the City right-of-way in front of houses, to be retained and protected in new development situations. Similarly, staff will be looking to see new developments design lots with room to retain and protect trees in rear yards. Both street trees and rear yard trees provide important benefits to many neighbours and to the street and surrounding neighbourhood. Trees in these locations should be considered early in the design process for a site so that adequate space is planned for, to protect the trees during construction.

For trees that are located within the existing as-of-right building envelope, City staff will issue a tree permit because that area has been established in zoning as the part of the site for a building to be located. Decisions to retain or remove trees that are located very close to the building envelope will have to be made on a case by case basis depending on the size and condition of the tree and the construction plans for the site.

For boundary trees, which are trees of which any part of the trunk is growing across one more property lines so that they are jointly owned trees, the permission of both property owners would be required before the City can issue a permit for the tree’s removal.

Adjacently owned trees are trees that are located on adjacent properties but that have roots that extend onto a development property. Adjacent trees must also be considered in the design process and protected during construction. The City cannot issue a permit to injure or destroy a tree on a property adjacent to a development property unless it is requested by the owner of the tree.

Consider and prioritize trees early in the design process. Use this diagram as a guide for which trees should be prioritized for retention on the site.

How to measure a tree

The Tree Protection By-law includes several requirements that reference the diameter at breast height (DBH) of trees. Permit requirements for privately owned trees are based in part on the diameter of the tree. The diameter of City-owned trees is taken into account when determining the necessary compensation for their removal. Knowing a tree’s diameter is necessary when calculating the size of its critical root zone (CRZ) for protection. Some residents may also enjoy knowing just how big a tree is!

When measuring the diameter of a tree, the Tree Protection By-law requires that the measurement be taken at a height of 1.3 metres (51 inches) above ground level. Two methods are outlined below to help guide you in measuring the diameter of a tree:

  1. For a quick estimate, hold a metre stick up to the tree at 1.3 metres above ground level. One end of the metre stick should be placed approximately at the edge of the tree trunk. Hold the stick steady and read the number at the other edge of the tree trunk to approximate the diameter of the tree.
  2. It is more precise to use a measuring tape around the trunk of the tree, at a height of 1.3 metres above ground level, to determine the circumference of the tree (i.e., the distance around the trunk). To convert the circumference you have measured to diameter, divide the circumference (in centimetres) by pi (3.1416). This will give you the diameter of the tree.

For properties greater than 1 hectare in size, or for properties subject to a Planning Act application for a site plan, plan of subdivision or plan of condominium, a City-approved Tree Conservation Report is required for the removal of any tree measuring 10 centimetres (4 inches) in diameter or more. A tree with a diameter of 10 centimetres will have a circumference of 31.4 centimetres (12 inches).

For properties 1 hectare or less in size, where no Planning Act application applies, a permit is required for the removal of a distinctive tree, defined as a tree with a diameter of:

  • 30 centimetres (11.8 inches) or more on properties in the inner urban area (urban lands inside the Greenbelt). A tree with a diameter of 30 centimetres (11.8 inches) has a circumference of 94 centimetres (37 inches); and
  • 50 centimetres (20 inches) or more on properties in the suburban area (urban lands outside the Greenbelt). A tree with a diameter of 50 centimetres (20 inches) has a circumference of 157 centimetres (62 inches).

Maps showing the extent of the inner urban and suburban areas can be viewed on geoOttawa.

Special circumstances

For a multi-stemmed tree, the diameters of all the stems (trunks) are to be measured at 1.3 metres (51 inches) from the ground. If any of the stems measure 30 or 50 centimetres (11.8 or 20 inches) in diameter or greater, as applicable for the site location, it is considered to be a distinctive tree. Therefore, the by-law applies, and a permit is required for its removal.

Trees on a slope should be measured at 1.3 metres from the ground at the centre of the trunk axis (on the side of the slope) so the height of measurement is the average of the shortest and longest sides of the trunk.

Trees with a leaning trunk should be measured at 1.3 metres from the ground along the centre of the trunk axis (along the angle of the trunk) so the height of measurement is the height along the trunk.

A forked tree should be measured at the narrowest part of the main stem below the fork. If the base of the fork is too high to reach, the tree should be measured at 1.3 metres. The height of this measurement and the height of the fork should also be recorded (for example: 75 centimetres diameter at 0.8. metres, fork at 1.1 metres).

Tree Information Report

The Tree Information Report (TIR) is required as part of the application for a tree permit, where tree removal is proposed for infill development or non-development purposes. A TIR is the document that details all protected trees on a site and the justification for any tree removal requests, as well as any detailed mitigation strategies required to protect them. This report must be prepared by an arborist, forester, or other related professional with similar qualifications as defined in the Tree Protection By-law. For Planning Act applications involving site plans, plans of subdivision or plans of condominium, a Tree Conservation Report is required.

If a tree removal request is related to the tree’s condition and not to development or work proposed around it, a simplified (short) TIR is required, detailing the tree’s condition or other justification for removal, along with supporting documentation such as tree risk assessments or other reports, as applicable. This report should also include consideration for other mitigation options such as pruning or cabling, to prolong the life of the tree.

Where tree removals are requested for the purpose of development, construction or demolition, or if work is proposed within the critical root zone (CRZ – see definition) of a protected tree, a more detailed (full) TIR is required. The TIR should provide a more comprehensive view of the work and the trees on site, considering the above and below-ground impacts of all excavation, movement of equipment and placement of materials, installation and capping of services, grading and drainage, etc. to provide guidance on tree protection, mitigation measures, and any necessary removals. This report must be accompanied by a plan of the work proposed with the tree locations overlaid (e.g., on the grading, site, and construction plan, as applicable). This plan must also include any protected trees with critical root zones extending onto the subject property (e.g., trees on adjacent properties) and adequate protection measures for those trees.

The TIR must also account for trees to be retained, providing direction on the placement of tree protection fencing and other measures, and how to mitigate damage to protected trees when work must be done within the CRZ, such as pruning branches over the work area, or the use of hydrovac excavation for services, etc. This direction must provide sufficient detail for all contractors on site to understand the limits of their work area and their responsibilities with regard to maintaining the tree protection on site.

For sites with no protected trees on or adjacent to the area impacted by the proposed work, a statement must be included on the grading plan or site plan noting that there are no trees on the site.

Where the Tree Information Report submission is related to infill development or other construction projects requiring approvals, tree permits will be issued by Forestry Services in conjunction with the development approval (e.g., building permit, demolition permit, pool enclosure, etc.). However, these other approvals do not in themselves convey permission to remove trees.

When tree removals cannot be avoided and compensation planting is required, the TIR must include the locations and details of the compensation trees in the report and plan drawings, accounting for above and below-ground impediments to the future growth of the tree (e.g., hydro wires, driveways, services, etc.) and allowing enough space to accommodate an appropriate volume of soil.

Trees and infill development

Infill development is defined as low rise residential development that is not subject to site plan control, plan of subdivision, or plan of condominium. Infill development is an important mode of intensification within the urban area of the city where key services already exist, and to ultimately reduce urban sprawl. The existing trees in these locations provide vital ecological goods and services not only to the community they are in but to the city as a whole. The importance of balancing tree protection and development throughout the city has been supported through the new Tree Protection By-law, new development review and permitting processes, and the addition of application and compensation fees as well as staff resources.

The new trees and infill development processes apply to all infill development within the urban areas of Ottawa, including the inner urban lands inside the Greenbelt and suburban lands outside the Greenbelt.

Committee of Adjustment

Applications for Infill Development which require a severance or minor variance from the Committee of Adjustment (COA) must now include a long Tree Information Report completed by an arborist or other appropriate professional. This will allow for the Committee to properly consider the impact of the proposed development to the existing and future tree cover on site.

The City’s Infill Forester will review the COA applications with a focus on impacts to trees and provide tree-related comments and conditions to the City Planner and the Committee of Adjustment.

Pre-consultations with the Infill Forester ahead of application submission are encouraged, to clarify the new requirements and avoid delays with the application.

Building Permit

Applications for Building Permits for infill development within the urban area must include a full Tree Information Report completed by an arborist or other appropriate professional. These reports must be submitted along with the Building Permit Application Package as well as online. If the TIR recommends the removal of any protected trees, the online submission of the TIR must include a tree permit application; a fee will be applied for each tree requested for removal, up to a maximum of 5 trees.

A Forestry Inspector will review each file and work with the applicant to make any necessary modifications to minimize the number of trees impacted. Once the tree plan for the site has been finalized, the Forestry Inspector will determine the required tree compensation amount, which may include trees to be planted or a monetary payment or a combination of both, depending on the ownership and number of trees to be removed. Please see Tree Compensation for more information.

Please refer to How to consider trees in your project and General rules for considering tree permits before planning and designing your site. Consulting with the Forestry team before making your plans is strongly encouraged. The issuance of a Building Permit does not constitute the City’s approval to remove trees.

Submit your tree information report here! The online form allows you to submit all information required to apply for a tree permit, including your Tree Information Report.

Tree Conservation Report

A Tree Conservation Report (TCR) is required as a part of the application package for all Plans of Subdivision, Site Plan Control Applications, Common Elements Condominium Applications, and Vacant Land Condominium Applications where there is a tree of 10 centimeters in diameter or greater on the site and/or if there is a tree on an adjacent site that has a Critical Root Zone (CRZ) extending onto the development site. The CRZ is established as being 10 centimeters from the trunk of a tree for every centimeter of trunk DBH measured in a radius around the tree. The CRZ is calculated as DBH x 10 cm.

The purpose of the TCR is to demonstrate how tree cover will be retained and protected on the site, including mature trees, stands of trees, and hedgerows, using a design with nature approach. A design with nature approach incorporates the natural features of a site into the design and engineering of a proposed development. The TCR will also show which trees must be removed on a site to accommodate the proposed development.

The TCR must be prepared by an arborist, as defined by the Tree Protection By-law. This includes Foresters, Arborists, Landscape Architects, or others with similar qualifications as approved by City staff. The TCR will be reviewed and approved by one of the City of Ottawa’s Planning Foresters. A tree permit for the site will be issued based on the information in the approved TCR.

The Tree Conservation Report Guidelines are contained within the Tree Protection By-law as Schedule E.