On the Markham side of Old Thornhill, repointing old brick needs a free Minor Heritage Permit unless the patch is under 1.5 square metres. Use soft lime mortar, cut out by hand. On the Vaughan side, ask first.
Brick looks like the easy end of heritage rules: nothing is changing, you are just fixing joints. In practice repointing is where well-meaning work does the most lasting damage, because a hard modern mortar can crack the old brick around it. Old Thornhill is also split down the middle by a city border, so which rules apply depends on which side of it your house sits. Here is what the published documents say, what we could and could not confirm, and what to settle before a mason starts grinding.
First, which side of the border are you on?
Old Thornhill around Yonge Street is covered by two heritage conservation districts, one from the City of Markham and one from the City of Vaughan. Only part of Thornhill is inside either, so do not guess from the street name. Our guide to small exterior jobs in the two districts explains how to check your address. Brick is also less common than you might expect: Markham's own plan says only a few brick buildings remain in its district, where wood siding and stucco dominate. If your house is painted wood or stucco, this article is not about you.
Markham: a free Minor Heritage Permit, with one small exception
Markham's heritage permit by-law (By-law 2023-20) lists "masonry cleaning and repointing" among the small projects that need a Minor Heritage Permit, and it says there is no application or administrative fee for one. So routine repointing of a wall is not something you can book first and tell the City about later.
There is a carve-out. The same by-law defines maintenance, which needs no permit, to include "re-pointing areas of wall space under 1.5 square metres", about 16 square feet. A few failed joints beside a step can fit under that. A whole front wall, or several patches that add up across a facade, do not. The by-law also recommends talking to Heritage Section staff about whether you need an application, and with a photo and a measurement that is a short conversation.
What Markham's plan says about mortar and tools
The permit is only half of it. Section 9.2.4.2 of the Thornhill Markham Heritage Conservation District Plan sets the standard staff will hold the work to, and it is specific:
- Only repoint when you must. Repointing should happen "only when it is badly deteriorated or when water penetration is a problem", and old mortar in good condition should not be disturbed. It is normal for old mortar to weather back a short distance from the wall face.
- Match the mortar. New mortar "should match the original in terms of colour, composition (soft, lime-rich variety for pre-1920) and pointing method."
- Use hand tools. Masonry and mortar to be replaced "should be cut out with handtools to minimize the risk of damage", because power tools can damage the brick edges.
- Why the wrong mix hurts. The plan calls the wrong mortar the greatest danger to old masonry. Modern mixes are harder, with more cement and less lime, while older lime-rich mortar is weaker than the brick and absorbs stresses. When the mortar is harder than the brick, the brick takes the damage instead.
- Leave the surface alone. Unpainted brick should not be painted, and brick should not be sealed with silicones or waterproof coatings, which can trap moisture behind the surface.
The plan also says repointing historic mortar can be complex and is best left to people skilled in it. That is a fair test for a quote: ask who is doing the work, how they cut the joints out and what they will mix.
Cleaning the brick first
Cleaning is on the same permit list as repointing. The plan says that if cleaning is wanted, only the gentlest method should be used, that sandblasting, high-pressure water jets and harsh chemical cleaners are not acceptable for historic masonry, and that the method should be tested on an inconspicuous spot first. A quote that says "pressure wash and re-grout the front" is the one to stop and question.
Vaughan: ask, and get the answer in writing
Vaughan's 2007 Thornhill plan works differently. Its list of activities exempt from review, which we read in earlier research, names caulking, weatherstripping, window repair and some fences, but we did not find repointing on it. We also could not open Vaughan's design guidelines for masonry when writing this, so we are not quoting a mortar mix or a rule for it. Treat that as an open question and ask. Vaughan's plan says even exempt minor work may need a Heritage Permit Clearance Letter from Cultural Services, so email CulturalHeritage@vaughan.ca with your address, a photo of the wall and a line on what is wrong, and keep the reply.
Whichever side you are on, the mortar advice above is sound practice for any pre-1920 brick: soft, lime-rich, matched to the original.
What to settle before anyone starts
- Which city and which district your address is in.
- The size of the job in square metres. Under 1.5 on the Markham side is maintenance; above it is a Minor Heritage Permit.
- Why the joints failed. A downspout splashing the base of a wall or a leaking joint above will undo new mortar.
- The mortar the mason proposes, written down, and how the old mortar will be cut out.
- Whether structural cracks or a bulging wall are involved, which is a different job from repointing and may need a building permit.
Quick answers
Do I need a permit to repoint brick in Old Thornhill?
On the Markham side, yes: repointing needs a Minor Heritage Permit, which has no fee, unless the patch is under 1.5 square metres. On the Vaughan side, ask Cultural Heritage staff first.
How much repointing is exempt in Markham's Thornhill district?
Markham's heritage permit by-law treats re-pointing areas of wall under 1.5 square metres as maintenance, which needs no permit. That is about 16 square feet, so a whole wall is not exempt.
What mortar should I use on old brick in Thornhill?
Markham's district plan says new mortar should match the original in colour, composition and pointing method, with a soft, lime-rich mix for pre-1920 buildings. Hard modern cement mortar can damage old brick.
Can I cut out old mortar with a grinder in a heritage district?
Markham's district plan says to cut mortar out with hand tools, because power tools can damage the brick edges. Ask any mason who quotes grinder work how they will protect the brick.
Can I paint or seal old brick in a Thornhill heritage district?
Markham's district plan says unpainted brick should not be painted, and brick should not be sealed with silicones or waterproof coatings, which can trap moisture behind the surface.
Settle the paperwork, then the brick
The permit costs nothing in Markham and the letter costs nothing in Vaughan, so the expensive mistake is the unasked one: hard mortar in old brick, or work redone to satisfy the City. When the written answer is in hand, Rhodex can match you with a vetted craftsman, backed by $5M liability insurance. Request a fixed price and attach the City's reply so it is built into the quote.
Related reading
- Rhodex in Thornhill: guides for homeowners
- All Rhodex services: get a fixed price
- Small Exterior Jobs in Old Thornhill's Two Heritage Districts: What Each City Exempts
- Touch-Up Painting and Caulking in a Thornhill Heritage District
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