How do you calculate project costs?

We use current market rates for high-quality materials and skilled labour in Durham Region. Every estimate includes a detailed breakdown of tasks so you know exactly where your money is going.

Is the initial consultation free?

Yes. We offer a free first meeting to look at your space and talk about your goals. After that we provide a clear price range for your specific project.

Do you offer fixed-price contracts?

Most of our projects use fixed-price contracts. This means the price we agree on is the price you pay, unless you decide to change the scope of work later.

What happens if material prices go up?

Once we sign a contract, we lock in the material prices for you. We order supplies early to make sure your budget stays safe from market changes.

How long will my renovation take?

Small jobs might take two weeks, while large additions can take months. We give you a full schedule before we start so you can plan your life around the work.

Will I have a dedicated project manager?

Yes. You will have one main person to talk to. They will be on site often to check quality and keep you updated on our progress every day.

How do you keep the job site clean?

We clean up at the end of every single day. We use floor protection and dust barriers to keep the rest of your home safe and tidy while we work.

Do I need to move out during construction?

For most room renovations you can stay home. For very large projects like whole-home guts, we might suggest staying elsewhere for a short time for your comfort.

What areas do you serve?

We serve all of Durham Region including Oshawa, Whitby, Bowmanville, Ajax, Pickering, Newcastle, Clarington, Scarborough, Stouffville, and Peterborough.

Do you handle permits and inspections?

Yes. We submit the plans to the municipality, get the permits, and schedule all required inspections to ensure your home is safe and the work is done to code.

Can you help with the design phase?

Yes. We work with designers and architects to help turn your ideas into professional drawings before we start building.

Do you do commercial construction?

Yes. We offer commercial services for offices, retail spaces, and restaurants alongside our residential renovation work.

What kind of warranty do you provide?

Every Cornerstone project is backed by a 5-year written workmanship warranty. If something we built fails because of how it was installed, we fix it at no charge.

What if I find a problem after you leave?

Contact us directly. We respond to warranty concerns within 1 to 2 business days and will schedule a site visit to assess the issue at no cost to you.

Are you insured and WSIB compliant?

Yes. Cornerstone Construction carries full liability insurance and all our workers are covered by WSIB. This protects you and your home completely.

Do you offer maintenance tips?

Yes. At the end of every project you receive a full Owner's Manual with care and maintenance instructions for every material and system we installed.

Ajax · Rental Income, Done Legally

Legal Basement Apartment in Ajax

Can you legally rent out your basement in Ajax? Yes — and Ajax goes big. One home can hold up to four. The Town pays you up to $12,000 to build. Your first suite needs no extra parking. A legal suite can help pay your mortgage, or house family. Here's what Ajax asks for, in plain words.

Start Your Basement Diagnostic Call 1-888-404-7383

Units allowed on most lots

$12k

Cash back, up to

Extra parking, first unit

Ajax Cash-Back Program

"Build More, Get More" — Money Back When You Build

The Town of Ajax pays cash back on new units, funded by the federal Housing Accelerator Fund. The more units you add, the more you get back — paid out after the build is done and the permit is closed.

1 unit added

$2,000

2 units added

$6,000

$3,000 per unit

3 units added

$12,000

$4,000 per unit

On or after July 2, 2025Permit application must be filed

First-come, while funds lastPaid once the permit closes

See If Your Ajax Property Qualifies

Rule Book 1 · Ajax Zoning

Why Ajax Is the Easy One

Ajax overhauled its second-suite rules in 2025 under By-law 23-2025 — and they're now among the most permissive in the region.

Up to Four Units

Most properties with a detached, semi-detached or townhouse home can now hold up to four dwelling units — a basement apartment, an upstairs unit, a garage conversion, a garden suite, or a mix.

How many your lot allows depends on its zone, size and setbacks. We confirm that during planning.

No Extra Parking for Your First Suite

This is the rule that removes the biggest obstacle: your first ADU needs no additional parking. A typical detached home with its two spaces can add a basement apartment with zero extra parking.

Only the third and fourth units need a space each, and tandem parking is allowed — so you rarely widen anything.

Check Your Property First

Ajax has a free ADU Property Mapping Tool — type your address and see whether a unit is permitted, plus your zoning, setbacks, buildable area and parking, at map.resimate.build.

It's a quick first read, not a full feasibility review. We confirm what's actually buildable and handle the zoning and permit work.

A legal suite is fully self-contained — it needs its own kitchen and bathroom. We build both to the standard of our kitchen renovations in Ajax and bathroom renovations in Ajax, with flood-tested waterproofing.

What Happens After You Call

You Handle Almost Nothing

You don't deal with the Town. You don't chase permits. And we time the whole thing to protect your grant.

We Check Your Property

A free visit. We confirm your zone, how many units your lot allows, parking, and whether the grant applies.

We Design & File

Plans drawn and filed through Ajax's eApply portal — permit dated to qualify for the cash-back.

We Build & Inspect

Built to code, every inspection booked and passed. You watch each step in your portal.

Permit Closed, Grant Paid

The grant is released once the build is done, inspections pass, and the permit closes. Then you rent it out.

Rule Book 2 · Inside the Suite

What the Building Code Requires

The Building Code keeps the suite safe, and it's the same across Ontario. The parts that matter most in a basement:

The Essentials

Ceilings at least 1.95 m (6 ft 5 in), dropping to 1.85 m under beams. Low headroom is the most common thing that needs design work first.
An escape window in every bedroom — big enough to climb out of in a fire.
Fire separation between your suite and the unit above.
Hard-wired, interconnected smoke and carbon-monoxide alarms.
Minimum room sizes so the space is genuinely livable.

See the full room-by-room size table in our Durham guide

Why Build It Legal

A Registered Suite Is Worth More

Real Income

With up to four units, an Ajax property can bring in serious monthly rent — money that counts on a mortgage.

Resale Value

A permitted suite adds verified value and sells clean. An unpermitted one is a liability a buyer walks from.

Safe & Insured

Code-built fire separation and alarms protect your tenants — and an undisclosed unit can void your policy.

The Grant Requires It

The cash-back only pays on a permitted, inspected, closed-out build. Legal isn't just safer — it's how you get paid.

Common Questions

Ajax Basement Apartment FAQ

How many units can I really have on my Ajax property?

Under By-law 23-2025, Ajax permits up to four dwelling units on most properties with a detached, semi-detached or townhouse home. The exact number for your lot depends on its zone, size and setbacks — we confirm that during planning, and you can get a first read from the Town's mapping tool at map.resimate.build.

Do I need extra parking for a basement apartment in Ajax?

For your first ADU — no. Ajax requires no additional parking for the first additional unit, so a typical detached home that already has two spaces needs nothing extra. The third and fourth units each need one space, and tandem parking (one car behind another) is allowed.

Can I actually get cash back for building one?

Yes — the Town of Ajax's Build More, Get More grant pays $2,000 for one unit, up to $6,000 for two, and up to $12,000 for three, funded by the Housing Accelerator Fund. The building permit application must be submitted on or after July 2, 2025, grants are first-come first-served while funds last, and the money is paid after the permit is closed. We confirm eligibility and time the application to protect it.

My basement ceiling feels low — is that a dealbreaker?

Not necessarily. The Code requires about 1.95 m (6 ft 5 in) across living areas, dropping to 1.85 m under beams and ducts. Many Ajax basements qualify; where they're tight, design choices (relocating ducts, adjusting the layout) often solve it. We assess this early so there are no surprises.

What affects the cost of a legal basement apartment?

Ceiling height and whether the floor needs lowering, a separate entrance, egress windows, the kitchen and bathroom layout, fire separation, and electrical/HVAC separation all drive cost. Ajax's no-extra-parking rule and the cash-back grant can reduce your net cost significantly. After a site visit we give you a clear, locked scope and price — not a guess.

What happens if I build a suite without permits?

You lose the grant entirely (it only pays on a closed, inspected permit), your home insurance can be voided, you can be held liable in a fire or injury, and the rental income may not count toward financing. Building it legal protects your home, your tenants and your money.

Bylaw and grant information last reviewed July 2026. Municipal requirements, grant funding and deadlines can change — Cornerstone confirms current Town of Ajax requirements with the Planning & Development Department on every project. Sources: Town of Ajax Housing & ADU pages; Zoning By-law 23-2025; Ontario Building Code.

Part of Our Durham Legal Suites Guide

See requirements for every Durham town, plus the full second-suite overview

Back to Hub →

Also building legal suites in Pickering, Whitby, and across Durham Region.

Up to Four Incomes. Up to $12,000 Back.

Start with a free basement check. We'll tell you how many units your lot allows, get your permit in before the grant runs out, and give you one locked price. No pressure, no surprises.