In Campbellville, Your Lot's Escarpment Designation Decides Whether a Second Unit Is Allowed

Where a second unit is allowed in Campbellville under By-law 004-2026

Milton finished its rural additional-unit rules in January 2026. Under notice Z-12/25 Council passed urban By-law 005-2026 on 26 January 2026 and rural By-law 004-2026, which applies to all lands in the Rural Zoning Area and takes effect with Official Plan Amendment 94; the Town's March 2026 rural zoning consolidation carries the new Section 4.25. Campbellville's residential streets are zoned Village Residential (RV), and the RV zone now permits an additional dwelling unit only in accordance with 4.25, which splits the hamlet in two.

On RV or Hamlet Commercial (C4) land inside the Niagara Escarpment Plan Area on the by-law's Schedule F, the answer follows the Escarpment designation under your lot. Escarpment Natural Area or Escarpment Protection Area: no additional unit. Escarpment Rural Area: one unit, inside a detached house, never in a detached accessory building. It is also barred on a lot with more than one detached dwelling, or in a house running shared housing or a bed and breakfast.

On RV land outside the Plan Area the unit may go in the house or an accessory building, but a lot on full or partial private water and sewage is capped at one unit, and an accessory-building unit not connected to municipal water and sewer needs at least 1.5 hectares; the RV zone's own minimum lot is 6,000 square metres, so most village lots fall short. The Greenbelt Plan generally does not apply inside hamlet boundaries. Units are prohibited on land a conservation authority has identified as hazard land or regulatory flood plain unless the authority permits one.

Size, parking and the 1.2-metre path: the numbers that shape the unit

In the RV zone each additional unit inside the house is capped at 110 square metres of floor area, excluding unfinished basements, stairs, cold cellars and unfinished mechanical rooms. Parking is one space per additional unit on top of the two the house already needs. Only one dwelling unit on the lot may be a short-term rental, and inside the Plan Area no home occupation or cottage industry is permitted within the unit.

The entrance rule is the one we tape first. You need an unobstructed pedestrian route at least 1.2 metres wide with 2.1 metres of vertical clearance from the street line to the exterior door giving the most direct access to the unit. Utility meters may sit in that width, window wells may project up to 0.3 metres, and a gate needs a clear opening of 1.02 metres. An above-grade side door can be served by a landing under 0.6 metres high and no larger than 0.9 by 0.9 metres, with stairs front and back where needed.

Where a detached unit is available, Table 4B sets the envelope: in the RV zone, 6.0 metres from the front and side lot lines, 10.5 metres from the rear, 5.5 metres from the house, a first storey no larger than 10 per cent of the lot or 110 square metres, and a height of 3.5 metres flat-roofed or 4.3 metres pitched. The Town also requires the unit to be registered, with a one-time fee of $340 per unit, in a program that began 1 April 2025.

Who regulates your lot: the Escarpment Commission or the Town

Campbellville is one of the villages the Niagara Escarpment Plan designates as a Minor Urban Centre, and the Plan allows land use in such a centre to be exercised either through Planning Act by-laws or through the Commission's Development Control. Milton's rural zoning by-law says it applies to all lands except those within the Plan Area, which are subject to development control administered by the Commission. Yet at its June 2025 information session the Town described the parts of Campbellville inside the Plan Area as not regulated by the Commission but by the Town's zoning, with Plan policies still applying, and Schedule F of the by-law maps the Escarpment designations across the hamlet on that basis.

Outside the hamlet boundary the picture is plainer. Milton's residential permit checklist lists Commission approval as required for any construction or development proposed within the Niagara Escarpment, and the Commission states that municipal building approvals can only be issued after the Development Permit. Applying is free, a planner is assigned when the package arrives, routine applications may receive a director's approval while non-compliant or objected-to ones go before the Commission at a scheduled meeting, and anyone who receives the notice of decision has fourteen days to appeal to the Minister. A secondary dwelling unit is not exempt: the Commission's own FAQ says establishing one also requires a permit.

The first step for any Campbellville address is the Commission's interactive map, which shows whether a lot is in the Plan Area and in the Area of Development Control.

Additions and renovations on escarpment lots: what the Commission exempts

Under development control, the Commission publishes exemptions and expects the owner to self-evaluate; it will not issue a confirming letter, and an exemption does not relieve you of the Building Code or other permissions. Interior work is exempt where it does not change the use of the building, which the Commission says takes in major renovations and the finishing of basements, but not carving out a secondary dwelling unit.

An addition is exempt where all additions to the original house total 93 square metres or less, its height is no more than the original dwelling, and it sits at least 4.5 metres from the side lot line, 7.5 metres from the rear and 15 metres from the front. Decks, porches and patios are exempt up to a combined 56 square metres; a shed or garage up to 72 square metres or 5 per cent of the lot, whichever is less, and 4.5 metres tall, with secondary dwelling units and habitable space excluded. Repairing or replacing a septic that serves only its own lot is exempt; a new system on a lot that had none is not.

Where a permit is needed for a unit, the Plan's development criteria govern the design: a single secondary dwelling unit on an existing lot of record, contained within the single dwelling or an addition to it, subordinate in floor area, never in a detached accessory facility, not alongside a bed and breakfast, and with no home occupation inside it. Milton's by-law mirrors those terms.

Wells, septic and Conservation Halton

Campbellville runs on private wells and septic. The Official Plan treats water and wastewater as Regional responsibilities, notes that Halton adopted hydrogeological studies for Campbellville, Brookville and Moffat in 1982, and ties the hamlet's minimum lot size for new development to the Region's Campbellville study. The septic permit itself is issued by the Town of Milton's Building Division through the same online portal as the building permit.

Milton's residential permit checklist governs what happens when you add space. An addition that increases finished floor area by more than 15 per cent, adds a bedroom or adds plumbing fixtures requires a septic evaluation report covering the existing system, daily design flow calculations, soils and tank and bed sizes, and any part undersized for the new daily design flow must be brought up to Part 8 of the Building Code. A new dwelling unit needs a full septic design. A Halton Region well approval sits on the same approvals list, and the Town runs a mandatory septic maintenance inspection program that notifies owners by mail.

Conservation Halton regulates a 15-metre allowance beyond the flood plain, stable top of bank or meander belt of a watercourse and 30 metres from a wetland, and within 30 metres of a provincially significant wetland or any wetland of 2 hectares or more no new septic system is permitted. Milton's Campbellville schedule shows a regulatory storm flood plain and the Natural Heritage System inside the hamlet, so a lot near Campbellville Pond or the creek should expect the authority's permit alongside the Town's.

Campbellville's houses and how HMH approaches the work

The village takes its name from John Campbell, who settled here in 1832; it became a police village in 1914 and grew around a sawmill and an 1849 store and post office, with its commercial core today around Guelph Line and Campbellville Road. Nassagaweya was surveyed in 1819, and the Official Plan describes the vernacular shifting northward through the township, fieldstone, frame and brick interspersed with quarried and cut limestone. Around the old core sit estate-scale lots, the RV zone asking 45 metres of frontage and 6,000 square metres, and the Plan caps the hamlet at 1,080 persons with no expansion of its boundary. A Community Improvement Area covers the Main Street core, and a designated heritage property needs a heritage permit before construction.

We measure before we quote. A rubble-stone foundation with a shallow cellar and a deep poured basement call for different answers on a legal unit, a walkout or a finished basement, and on a septic lot the drawing set has to carry the evaluation described above. HMH Construction is a licensed, WSIB-covered general contractor with offices in Milton and Mississauga. We prepare the permit drawings, file through the Town's portal, and carry the Escarpment Commission, Conservation Halton and septic approvals as part of the job. Separate basement entrances and walkouts are our specialty, built in three days once permits are in hand, engineering, excavation, waterproofing and inspections included. We also build legal basement apartments, garage conversions and multi-unit conversions, kitchens, bathrooms, finished basements and whole-home renovations, home and second-storey additions, and commercial fit-outs for Main Street storefronts.