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How To: Tree Protection for Construction

Friday October 19th, 2018

In many regions across Canada, municipal bylaws require that trees are protected during construction. Generally, you have two options: you can either take steps to protect the trees from potential damage due to construction, or you can replace any trees that are damaged or removed during the job. In some cases, you may find yourself doing both. Most cities are working to maintain or increase the canopy cover, so you cannot remove a tree without replacing it.

There can be steep fines if you fail to meet your municipality’s requirements for tree protection. Paying to replace injured or removed trees is also costly. In fact, experts agree that it is less expensive (and more important) to protect existing trees than to replace trees removed during construction. That remains true even after accounting for the costs associated with tree protection, such as obtaining an arborist report and installing protective hoarding.

Why Is It Important to Protect Trees?

Trees are crucial to the well-being of our communities for a number of reasons. They benefit our health in a myriad of ways, trapping dust and absorbing airborne pollutants. They provide shade from solar radiation and help reduce noise in our neighbourhoods. Research has even shown that within minutes of entering a green space surrounded by trees, your blood pressure decreases, your heart rate slows, and you feel less stressed.

Trees also benefit our environment, absorbing carbon dioxide as they grow and helping to slow the rate of global warming. They host complex microhabitats, providing a home and nourishment to communities of birds and insects. In fact, a mature oak can host as many as 500 different species of wildlife!

For those of you in the home-building industry, there is another especially compelling reason to preserve the trees on site. Research actually indicates that average house prices are as much as 18% higher when properties are close to mature trees!

How Can Construction Damage Trees?

Most people are not even fully aware of all the ways construction activity can hurt a tree. The potential impact extends way beyond cutting a tree down or damaging its branches.

The roots of a tree can easily extend beyond the edge of its canopy (known as the “drip line”). They’re usually found in the top 8 to 10 inches of soil, leaving them susceptible to damage during excavation or topsoil removal. The simply act of driving heavy equipment through the “root zone” can have disastrous effects. Heavy machinery will compact the soil and cause roots to die, which is just as bad as digging.

How Do I Create a Tree Protection Plan?

We sought the advice of Toronto-based consulting arborist Lauren McLaughlin, who runs The Urban Forest Company. Lauren broke the process down into a few simple steps for us:

  1. Determine if the trees on your property are protected by the municipal bylaws.
    Every municipality has different bylaws when it comes to tree protection, and some only require protection for certain species of trees. Check your municipality’s website to make sure that you meet the necessary requirements.
  2. If you’ve determined that the trees on your site must be protected, you’ll need to hire a certified arborist to produce an arborist report. The arborist report is usually a requirement of the building permit. This means you cannot obtain a building permit until Forestry approves the arborist report.
  3. The arborist will come and assess the trees on your site. They may also look at the trees on neighbouring properties if they might be impacted by the construction activity. A typical arborist report would seek to answer the following questions:
    • What is the current health and condition of the trees?
    • Will the trees be impacted by the construction activity? If so, how might they be impacted?
    • What can be done to protect them?
  4. At this stage, you must implement the arborist’s recommendations to protect the trees during construction. You can also apply for permits to injure or remove the trees, but you are still required to protect trees that you plan to injure.

In fact, most cities will not allow a healthy tree to be removed unnecessarily, so unless it is within the footprint of the planned structure, you may only be able to apply to injure the tree. The exception would be if the planned construction would cause the roots to be severed close to the trunk of the tree, as this compromises its structural integrity.

When it comes to the trees you are required to protect, most tree protection plans will involve some type of hoarding.

Different municipalities have different requirements for types of hoarding for tree protection. In most cases, the hoarding must prevent the passage of any sediment or debris. This means that if temporary fence is to be used, it must include a tight-knit screening. Check with your local municipality to determine which types of hoarding are acceptable.

By following the above steps, you can do your part to protect our trees and maintain the health and beauty of our neighbourhoods.

We’re here to answer any questions you may have.

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