Second-storey additions in Clarington

The overlay, added by By-law 2020-050, covers R1 lots shown on Schedule 3 of By-law 84-63, and it changes three numbers that matter when you build up.

The first is height: the overlay caps a house at 8.5 m to the midpoint between eaves and ridge, or 7.5 m for a flat roof, and starts measuring at "fixed grade": the ground level at the middle of the front lot line. If your lot climbs from the street, the house starts above that point and loses height; if it drops, you gain some.

The second is the side yard: a house of 1.5 storeys or less needs 1.2 m; anything taller needs 1.8 m. A bungalow sitting legally 1.2 m off the line would, on our reading, need 1.8 m once it becomes two storeys. Where Ontario's 90% setback rule applies, the figure drops to 1.62 m, still more than the bungalow has. The choices are stepping the new storey in from that wall or asking the Committee of Adjustment.

Coverage is the good news. The overlay cuts it to 35% on lots under 650 m², 30% from 650 to 799 m² and 25% over 800 m², which squeezes rear additions hard. A second storey adds no footprint at all.

The rest of Clarington's R1 land works to 10.5 m, 40% coverage and a 7.5 m rear yard. Height there is measured from the lowest finished grade beside any wall, so on a walkout lot the low side sets the start. Clarington has the highest share of detached houses among Durham's five lakeshore towns: 77.7% of its occupied homes in the 2021 Census were single-detached houses. The Municipality warns its posted by-law text is out of date, so we confirm the zone with planning staff first.

Schedule B has no separate line for an addition. The $17.73 per m² Group C rate is our inference from how the schedule charges by occupancy, so confirm it with the Building Division. A 90 m² storey works out to about $1,596 at 2026 rates. Fees rise 3% each 1 January, which takes the rate to about $18.26 in 2027 (our arithmetic). If the engineer changes the design after the permit issues, a revision costs $182.03 an hour, one hour minimum.

A residential minor variance is $2,280, filed online through Service Clarington since October 2025. The Committee holds a public meeting and decides within 30 days of a complete application, with a 20-day appeal period. Only 14 new applications came in during 2025 (7, 2, 3 and 2 by quarter). That says the Committee isn't backed up; it says nothing about how second storeys fare there.

Clarington is split between three conservation authorities: CLOCA in the west, Ganaraska Region from Wilmot Creek east, and Kawartha Conservation where the north drains to Lake Scugog. Under O. Reg. 41/24, a storey that enlarges a building in a regulated area needs that authority's permit.

The nearest second storey we've finished is West Lynde, in Whitby about 20 km west of Clarington's centre: a bungalow taken to two storeys in about 4.5 months on site, under one single-slope roof instead of the valleys on the drawings. Greenwood, our rear extension and new top storey in Toronto, is about 58 km away; there we protected a double-brick side wall by removing and rebuilding floor sections in stages.