HMH Construction — Masters of Renovation

Serving Ajax

Ajax Dropped the Extra Parking Rule on a First Basement Unit

Ajax is one of the easier places in the GTA to add a unit right now, and most of what you'll read online about it is out of date. In March 2025 the Town rewrote its zoning through By-law 23-2025.

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What We Build in Ajax

Home Renovations

Kitchens, bathrooms, basements and whole-home renovations in Ajax — fixed-price quotes from one accountable contractor.

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Multifamily Conversions & ADUs

Legal basement apartments, garden suites and garage conversions in Ajax, designed and registered to Ontario second-unit rules.

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Separate Basement Entrances & Walkouts

Separate basement entrances and walkouts in Ajax — built in 3 days with permits, engineering, waterproofing and inspections handled.

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Commercial Construction

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We Know Ajax's Rules

Second units and basement work in Ajax

The part that changes the math on a driveway walkthrough is parking. Under the current by-law, the first accessory dwelling unit on a lot requires no additional parking beyond what the principal dwelling already needs. Only the second and third units need a space each. If someone told you Ajax wants three off-street spaces before it will consider a basement apartment, that was the old rule and it is gone.

Ajax also treats a below-grade entrance as its own building permit type instead of burying it inside the apartment application. The Town's form asks for a legal survey or site plan, fully dimensioned architectural drawings carrying a qualified designer's BCIN, a cross section cut through the basement walkout, and clearance from Toronto and Region Conservation Authority where the property is affected. That structure works in your favour: we can get the entrance approved and cut on its own, and permit the suite behind it after. It is part of why our separate entrance jobs hold a three-day site schedule — excavate, form and pour the stairwell, set the door and sill, back-grade and tie in the drain, then leave the interior to the apartment permit.

The zoning detail we check before anything else in Ajax is the side yard. Both attached and detached units must have a primary entrance served by an unobstructed path at least 1.2 metres wide running to a driveway, street or lane. On the tighter 1980s subdivisions around Westney Heights and Applecroft, and on the narrow-lot 2000s stock in Audley and Nottingham, that 1.2 metres has to survive the stairwell guard, the gas meter, the AC condenser and the neighbour's downspout. We put a tape on it before we quote, not after.

Ajax's housing stock arrived in distinct waves and they behave very differently below grade. The oldest part of town is the wartime core, roughly 600 CMHC houses built from 1941 for the Defence Industries Limited shell plant and only placed on permanent foundations once the war ended — those are the last houses in Ajax we would promise a legal suite in without measuring first. Pickering Village is older still, an 1800s village core with a heritage conservation district over part of it, so anything visible from Old Kingston Road or Church Street gets a heritage look before it gets a permit. Pickering Beach began as 1920s summer cottages for Toronto families and has been rebuilt piecemeal ever since, which is why foundations down there are the least predictable in town. The suites that go smoothly come out of the two real building booms — the 1980s, and the north Ajax wave that took the town from about 74,000 people in 2001 to over 109,000 by 2011. The newer the pour, the better your odds of clearing headroom without underpinning. We measure to the underside of the joists and to the bottom of the main trunk duct on the first visit and tell you straight whether the ceiling works or whether you are looking at lowering the floor.

The hard no in Ajax is hazardous land. The zoning by-law prohibits accessory dwelling units, attached or detached, on lands a conservation authority has determined to be hazardous, including regulatory flood limits and erosion hazard limits. That is not theoretical here. The lower Carruthers Creek area between Pickering Beach Road and Shoal Point Road, south of Bayly, is a recognised flood vulnerable cluster where roughly 90 properties sit in the flood plain, and the Lake Ontario shoreline through Ajax has live erosion hazard after the 2017 and 2019 high-water years. If your address falls in there we say so at the first visit rather than take a deposit and discover it at plan review.

If there is already a unit downstairs and Ajax Fire has been through it, that is a different application again. The Town issues a separate permit to bring an existing accessory apartment up to Section 9.8 of the Ontario Fire Code, and the submission has to include the Notice of Violation report from Ajax Fire and Emergency Services along with drawings showing every fire separation and its rating, all self-closers, and the location of every smoke and carbon monoxide alarm. That retrofit work is normal for us. Out in rural north Ajax inside the Greenbelt Plan Area the rules tighten instead: one accessory dwelling unit maximum, nothing within the Greenbelt Natural Heritage System boundary, minimum distance separation formulae apply, and where the property is on septic the Durham Region Health Department has to clear it before the Town will issue.

HMH Construction has been building in the GTA for more than 25 years, out of a head office in Mississauga. We are WSIB covered and fully insured, we prepare and carry the permit drawings ourselves through the Town's online application portal, and we chase the conservation authority and Region of Durham clearances as part of the job instead of handing you a list. Alongside separate entrances and legal second units we build garden suites and garage conversions, home additions, and full renovations — kitchens, bathrooms, basements, flooring, tile and countertops. We have a completed bathroom renovation in Ajax we are happy to walk you through. Call 905-749-4608 and we will give you a straight read on your address.

Ajax requirements

Ajax allows up to four units on a lot. By-law 23-2025, passed 24 March 2025, permits up to three attached units, or one detached unit on its own, or a combination — one attached plus one detached, or two attached plus one detached. The ceiling is four dwelling units on the lot including the house itself. For most homeowners that means a basement suite and a backyard unit are both on the table at the same address.

Check the zone, and ignore the stale advice. Attached and detached units are both permitted in CR, R1-A through R1-F, R2-A, R2-B, R3, RM4, RM5 and RM6. A lot of pages still say RM4, RM5 and RM6 are excluded — that was true before the 2025 rewrite and it is not true now. If someone tells you your zone rules you out, ask which consolidation date they are reading.

Detached units have their own numbers. A detached unit has to sit at least 3.0 metres from any other building on the lot, meet the performance standards for accessory buildings, and have a ground floor area smaller than the house's. On Greenbelt land north of the urban boundary it is one unit maximum, it has to fall outside the Greenbelt Natural Heritage System boundary, and minimum distance separation formulae apply.

Three jobs, three different forms. Ajax splits this work up more than most towns do. A below-grade entrance is form PLD-078 and is its own permit type. A new accessory apartment is PLD-072. Bringing an existing unit up to Section 9.8 of the Fire Code is PLD-070, and that one has to include the Notice of Violation report from Ajax Fire and Emergency Services. Knowing which form you are actually on before you start is most of the battle — we prepare and submit them either way.

Everything goes through the Town's portal. Residential permit applications run through the Town's online application portal at eapply.ajax.ca, launched in April 2025. Anything that cannot go through the portal goes to [email protected], and Building Approvals sits at 65 Harwood Avenue South. We file on your behalf and chase the Region of Durham and conservation authority clearances as part of the job.

Ajax is TRCA, not CLOCA. All of Ajax falls under Toronto and Region Conservation Authority, which administers both the Duffins and Carruthers watersheds. If your lot backs onto a valley or sits near the lake, TRCA clearance is part of the permit rather than an afterthought — and on hazardous land, a flood limit or an erosion limit, an additional unit is simply not permitted. We tell you that at the first visit, not at plan review.

Check your own address before you call anyone. The Town runs an ADU Property Mapping Tool on its housing site that will tell you in about three steps whether your lot qualifies for a detached backyard unit or an internal one. It is worth two minutes. Then call us at 905-749-4608 and we will tell you what it actually costs to build.

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Ajax Neighbourhoods We Serve

Projects We've Built in Ajax

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Bathroom Renovation in Ajax: Finishing What Another Contractor Left — completed by HMH Construction

Ajax

Bathroom Renovation in Ajax: Finishing What Another Contractor Left

Ajax, Ontario. We ground the existing shower pan back to a true slope, rebuilt the wet areas on cement board, and finished the room in large-format marble-look porcelain — 13 working days, start to handover.

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What Ajax Homeowners Say

Google 4.9★ (164 reviews across our Milton & Mississauga locations) · Consistently 5.0★ on HomeStars

“Very honest and upfront with the scope of work and pricing. Hard to find this in the construction space. Best part was that they were on time and on budget. Highly recommend!”

Jabir Mahida · Google review · Renovation

“They finished our unfinished basement to a legal apartment. … They were very responsive and their communication was excellent, which I appreciated. The work was done very well and the quality was impressive.”

Rifqa Ahsan · HomeStars review · Legal Basement Apartment

“From taping off the rest of our home to help eliminate dust and the thorough follow up at the end… They were professional, reliable and most importantly they delivered on time.”

Laura · HomeStars review · Basement Renovation

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