Fences and Decks in a New Build Backyard

You closed, you have the keys, the back yard is bare and you want a fence. Here is the part nobody explains at the builder walkthrough: the yard is yours, but for the first few years what you can do with it is limited by an agreement you were not a party to.

Get the order wrong and it can cost you a deposit you did not know your builder was holding.

The grading deposit is your builder's money, not the city's

This is the single most misunderstood thing about new subdivisions, and it is the one point that holds true everywhere we checked.

That deposit on your closing statement for grading and sod is held by your builder under your Agreement of Purchase and Sale. The municipality does not hold it, cannot release it, and will not usually get involved. Aurora puts it about as plainly as a town can: grading deposits taken by a builder are not a requirement of the Town, and the Town is not party to them.

So when people say the city is holding your deposit, they have it backwards. Your leverage, and your risk, sit with the builder.

Final lot grading certification is the gate

Your lot was built to an approved grading plan. Before the deposit comes back, the developer's engineer has to certify that the lot actually got built that way. Not the city, and not an inspector who works for the city.

Until that certificate exists, several GTA municipalities restrict what you can put in the yard:

• Aurora says that in an unassumed subdivision you cannot build a fence, shed, deck or pool without the developer engineer's permission, specifically to protect drainage patterns.
• Clarington will not issue a building permit for a deck or pool enclosure until the developer's engineer has certified the lot grading.
• Milton requires a developer's clearance letter from the builder before it will permit a deck, if the subdivision has not been assumed yet.
• Oshawa tells homeowners to hold off on landscaping, structures and pools that could alter grading until certification is done.
• Pickering says accessory structures such as decks typically cannot be built until final lot grading certification is issued.

Not every municipality publishes a hard gate like this. But the pattern is common enough that the first question to ask your builder is not whether you can build, it is whether your lot has been certified yet.

No municipality we found publishes a rule saying in so many words that putting up a fence forfeits your deposit. What they do publish is that certification is required before the deposit is released, and that structures must not disturb the grading. Those two facts sit next to each other for a reason.

Assumption is a different, later thing

Assumption is when the municipality formally takes over the subdivision's roads and services from the developer. It matters because it is usually when deposits come back and when the town, rather than the builder, becomes the people you deal with.

How long it takes genuinely varies, so be careful with any single number you read:

• Brampton: usually four to six years after registration, and typically one to two years after the final coat of pavement goes down.
• Pickering: three to six years after registration.
• Oshawa: typically five to six years after registration.

The final coat of asphalt on your street is the useful visible signal. Brampton also publishes a property assumption status lookup, so you can check rather than guess.

Which fences the builder puts up, and which are yours

In most subdivisions the developer fences the boundaries the subdivision agreement requires, and nothing else. Brampton publishes its standards in full, and the pattern is typical:

From the City of Brampton subdivision fencing and wall standards. Other municipalities set their own, so check yours.

Oshawa says the same thing in a sentence: developers install acoustic, corner lot and perimeter fencing, and fencing between lots that is not shown on the approved plans is the homeowner's responsibility.

That is why a new street often has handsome fencing along the park side and bare property lines everywhere else.

Your subdivision may dictate the style too

Many subdivisions have architectural control guidelines, drafted by the developer's control architect, approved by the municipality and written into the subdivision agreement. They can cover fencing alongside everything else about how the street looks.

These are specific to your subdivision, so there is no general rule to quote. Ask your builder for your subdivision's guidelines before you settle on a style, particularly if your fence will be visible from the street.

Easements and swales: the part that actually bites

New lots are drained deliberately. There will be shallow grassed channels, called swales, running along side and rear lot lines, and on some lots a rear yard catch basin, which is a concrete inlet with a metal grate set flush with the lawn.

• You cannot fill or alter a swale. Clarington and Pickering both say so outright, and Whitby prohibits anything that interferes with a swale, ditch, culvert or catch basin. It is not only your lot you would be affecting.
• You cannot build structures in an easement. Pickering prohibits any structure within one. Oshawa can require a structure blocking easement access to be removed at your expense.
• A rear yard catch basin signals an easement. Pickering requires them to sit in an easement at least 3 m wide, so that grate in your lawn is telling you something about where your fence cannot go.

Whitby offers the most practical rule of thumb we found: do not change anything within 60 cm of the property line, because that is usually where the swale runs.

Can fence posts go in an easement? We are not going to give you a general answer, because the municipal language prohibits structures without carving out posts, and we could not find a single municipality that publishes an exception. Treat it as not allowed until your municipality's engineering department tells you otherwise for your lot, and check your title and reference plan for what easements you actually have.

Book your locates, and know what they do not cover

Ontario One Call locates are free and legally required before digging. Request them at least five business days before the crew arrives. There is no exemption published for fence post holes.

The trap is what the free locate does not include. Public locates cover utility-owned gas, electricity, telecom, water and sewer. They do not cover private lines on your own property, and those are yours to have marked by a private locator:

• The gas line running to a BBQ or pool heater
• Electrical to a shed or detached garage
• Lights or signs on the property
• Sewer and septic tanks, systems and piping
• Security camera and low voltage lines

On a new build there is often less buried than on an older lot, but the gas line to a rear BBQ outlet is common and sits exactly where a fence line goes.

What this does to your Tarion warranty

Careful here, because this gets overstated online constantly.

Building a deck or fence does not void your new home warranty. Tarion publishes no such rule and we are not going to invent one.

What Tarion does say is that alterations, deletions or additions made by the homeowner are not covered, and neither are defects in materials or work the homeowner supplied. Your deck is your deck. Separately, surface grading and ponding are covered, but only under the one year work and materials warranty, while water penetration through basement or foundation walls is covered for two years.

The real risk is causation. If your work changes how the lot drains and water later shows up in the basement, you have handed the builder a documented reason to say the cause was your alteration rather than a construction defect. That is not the warranty being void. It is a claim becoming much harder to win.

Which is the whole argument for doing it in the right order.

The order we would do it in

• Ask your builder whether final lot grading certification has been issued for your lot, and get the answer in writing.
• Check your subdivision's assumption status with the municipality.
• If it is not assumed, get written sign-off from the builder or the developer's engineer before anything goes in the ground. Milton will ask you for exactly this.
• Get your subdivision's architectural control guidelines from the builder if your fence will be seen from the street.
• Check your title and reference plan for easements, and walk the yard looking for swales and catch basins.
• Book locates five business days out, and arrange a private locator for anything on your own side.
• Then build, keeping fill and post spoil out of the swale.

It sounds like a lot. In practice it is two phone calls and a look at your survey, and it is the difference between a fence and a fence plus an argument about a deposit.

We build in these subdivisions constantly and we are used to the sequence. If you are not sure where your lot stands, send us your address and a photo of the back yard and we will tell you what we would check first. Our fence height guide covers what you are allowed to build once you are clear to go, and the footing depth guide covers how deep it has to go.

Sources: Brampton new subdivisions, Brampton fencing and wall standards, Oshawa new subdivision homeowners, Pickering new homeowner FAQ, Aurora lot grading and drainage, Clarington site alteration, Milton decks, Whitby drainage and grading, Richmond Hill architectural control guidelines, Ontario One Call, Tarion, what is not covered. Checked September 2026. Your builder and your municipality are the final word on your lot.