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Basement Suites in King, Ontario: design, permit and build on a single contract. A typical 700 sq ft unit estimates at $91,500-$148,000 (about $385/sq ft), with $9,000-$16,500 including York Region and septic charges in municipal approvals and a May-October construction season.

Legal basement suite conversions - underpinning, separate entrance, egress windows and fire separation to bring an existing basement up to a rentable second unit.
Service area
King, Ontario
York Region
Typical build estimate
$91,500-$148,000
about $385/sq ft in King
Municipal approvals
$9,000-$16,500 including York Region and septic charges
quoted separately from the build
Build season
May-October
150 cm snow · -5.3°C winter avg
Frost depth
1.2 m
footing depth, OBC Part 9
Local market
27,333
residents · walkability 21/100
King Township is almost entirely Oak Ridges Moraine and Greenbelt, with core-area designations that prohibit new building envelopes outright on some parcels. We run a moraine designation check against the property roll number before quoting a King City or Nobleton laneway-suite or garden-suite project, because on a core-area lot the honest answer is sometimes no. King Township permits additional dwelling units, with Oak Ridges Moraine and Greenbelt policies plus private servicing governing the majority of properties.
Estate and agricultural parcels, many over an acre, on private well and septic with moraine core-area restrictions. North-GTA snowfall of 150 cm and -5.3°C winters give King a May-October working season - foundations for basement suites go in before the ground closes, with interior finishing carried through the cold months.
A basement suite lives or dies on two measurements taken inside the existing King house: finished ceiling height under the joists, and whether a code-compliant egress window can be cut without undermining the foundation wall. Where the head height is short, we underpin or bench the footing - a wet-trades sequence that runs year-round indoors, which is why basement work is the form we schedule outside the May-October window. Fire separation between the two dwellings, an independent exit, and interconnected alarms are the three items that most often turn an existing finished basement into a non-compliant one.
Everything you need to know about our services.
A typical 700 sq ft build in King estimates at $91,500-$148,000 - about $385/sq ft, set by $9,000-$16,500 including York Region and septic charges in approvals, a 1.2 m frost-depth footing requirement and 150 cm of annual snow load. Final pricing follows the site visit.
Related service: Our ADU services
King Township permits additional dwelling units, with Oak Ridges Moraine and Greenbelt policies plus private servicing governing the majority of properties. Approval costs in King run $9,000-$16,500 including York Region and septic charges, quoted separately from construction so the permit stage holds no surprises.
Related service: Our ADU services
Estate and agricultural parcels, many over an acre, on private well and septic with moraine core-area restrictions. King is car-oriented at 21/100 walkability, so parking retention and driveway access constrain the footprint more than the zoning envelope does. We work regularly in King City, Nobleton, Schomberg.
Related service: Our ADU services
Often, yes, but a finished basement is not a legal second unit until it has its own exit, the required fire separation between dwellings, interconnected alarms and a ceiling height that meets the Ontario Building Code. We survey what exists in King first and price only the delta, so approvals stay near $9,000-$16,500 including York Region and septic charges rather than a full rebuild.
Related service: Secondary Suites
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