You just bought a house in Durham Region and there is a tree in the yard you want gone before the weekend is over. Maybe it is leaning toward the garage, or it is just in the wrong spot for the fence you want to build. Before you book anyone, the question that actually matters is whether your municipality requires a permit at all. Durham Region is not one set of rules. Oshawa, Whitby, Ajax, and Clarington each run their own bylaw, and the answer changes depending on which one your address falls under.

Start With Your Municipality, Not the Tree

None of the four Durham cities regulate private trees by trunk diameter alone, unlike some bylaws elsewhere in the GTA. Whitby, Ajax, and Clarington trigger a permit based on zoning, lot size, or proximity to protected land. Oshawa has no private tree bylaw at all for individual trees. Location and zoning are what to check first in every one of the four; diameter is not the deciding factor anywhere in the region.

Oshawa: No Permit for an Ordinary Yard Tree

Oshawa is the simplest case in the region. By-law 78-2008 protects City Trees only, defined as a tree with 50 percent or more of its trunk on municipal property. A tree that sits entirely on your own residential lot needs no municipal permit, regardless of species or size. Oshawa City Council has discussed extending protection beyond city-owned trees, but as of July 2026 no private tree bylaw had been enacted.

The exception is a tree on the city road allowance or on parkland, which falls under By-law 78-2008 and needs City approval. If you’re weighing removal against having the tree assessed first, our tree removal reports page covers what a report includes and when it is worth commissioning one even without a permit requirement. Full detail on Oshawa’s rules, including the Durham Region overlay below, is on our Oshawa permit guide.

Whitby: Check Your Zoning Before Anything Else

Whitby’s By-law 4640-00 does not cover every private tree. A permit is required only if the tree falls into one of these categories:

A woodlot between 0.2 and 1.0 hectares
Land zoned Environmental Protection, Conservation, Greenbelt, or Oak Ridges Moraine
A mature woodland or Environmentally Significant Area
A residential lot of 2.02 hectares or more
A designated heritage conservation district, including Werden’s Plan and Brooklin

Fall outside all five and a standard residential lot needs no municipal permit to remove an ordinary tree, at any trunk size. That covers most subdivision lots in Whitby, but the exemption has edges that are not obvious from the street: a heritage district boundary in particular can run through a block without any visible marker. Confirm your zoning before assuming the exemption applies. Our Whitby permit guide breaks down all five trigger categories in detail.

Ajax Runs on Location, Not a Diameter Chart

Ajax’s By-law 137-2006 protects trees in parks, Greenbelt land, Environmental Protection land, and certain open-space zones. There is no city-wide diameter threshold here, and any source quoting a specific centimetre figure for Ajax is wrong.

Single-dwelling lots under 1.2 hectares are exempt, unless the property is zoned Private Open Space. For most homeowners on a standard lot, that means an ordinary tree comes down without a municipal permit, at any trunk size. Because the exemption does not extend to Private Open Space zoning regardless of lot size, a larger or unusually zoned property is worth checking against the zoning map before you assume it applies to you. Details are on our Ajax permit guide.

In Clarington, the Trigger Is Woodlots and Wetland Buffers

Clarington’s Woodlot Preservation By-law 97-35 also runs on location rather than diameter. A permit applies to a tree that is part of a woodlot of 0.2 hectares or more, on Environmental Protection-designated land, or within 120 metres of a mapped wetland. Outside those three categories, an individual tree on an ordinary residential lot needs no municipal permit.

Clarington is Durham Region’s largest municipality by area, with substantial rural and wooded land around Bowmanville, Courtice, and Newcastle. A property with any meaningful tree cover, or one that backs onto a wetland, is worth checking against the woodlot and buffer triggers before you assume the tree in question is exempt. The Clarington permit guide covers all three triggers and how the 120 metre buffer is measured.

Building or Renovating? A Separate Set of Rules Applies

Everything above covers a standalone removal on an untouched lot. If you’re also planning construction, whether that’s a new build, an addition, or a subdivision of the lot, the calculation changes even where no private tree bylaw exists. All four municipalities require an arborist report and tree protection plan as part of site plan, subdivision, or building permit review whenever the project affects existing trees, independent of whether a standalone tree removal bylaw applies to that property.

This catches Oshawa homeowners in particular off guard, since Oshawa has no private tree bylaw at all for individual trees, but its Development Services Department still expects a tree inventory and protection plan on qualifying development applications. The same pattern holds in Whitby, Ajax, and Clarington: the construction-permit requirement runs alongside the tree bylaw’s own triggers, not instead of them, so clearing a bylaw exemption does not clear a development application.

The Rule That Applies Everywhere: Durham Region’s Woodland By-law

All four cities sit under one more layer: Durham Region’s Woodland By-law 30-2020. It applies on top of each city’s own rules and requires a permit before trees can be removed or injured in any woodland of 1 hectare or more, anywhere in the Region. This matters even in Oshawa, where there is otherwise no private tree bylaw at all. A cluster of mature trees on a large lot can meet the Region’s 1 hectare threshold even when it looks, at first glance, like an ordinary backyard.

The regional bylaw is independent of the city-level checks above. A property can clear its own municipality’s exemption and still need a Durham Region woodland permit if the treed area is large enough.

Your Weekend Checklist

Run through this before booking a removal:

Confirm which of the four municipalities your property falls under, since the rules differ meaningfully between them.
In Whitby, Ajax, or Clarington, check the tree’s zoning, lot size, or proximity to wetland against that city’s trigger categories.
In Oshawa, confirm the tree is not on the road allowance or parkland.
Estimate the treed area on the lot against Durham Region’s 1 hectare woodland threshold, regardless of which city you’re in.
If you’re also planning construction, such as an addition or a new deck, check whether a site plan or building permit application will require a tree inventory even where no standalone removal permit applies.

If any of those checks come back uncertain, that uncertainty is exactly what an arborist assessment resolves before a chainsaw shows up. Our broader guide to GTA tree removal permits walks through how these municipal rules compare across the rest of the GTA, if your Durham move came from elsewhere in the region and the differences are catching you off guard.

Tree Permit Rules for Oshawa, Whitby, Ajax, and Clarington, Compared